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Sample records for auger electron spectroscopy

  1. Photoelectron spectroscopy and Auger electron spectroscopy of solids and surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Kowalczyk, S.P.

    1976-01-01

    The use of photoelectron spectroscopy, primarily x-ray photoelectron spectroscopy, to obtain information on the electronic structure of a wide variety of solids (especially the bulk electronic structure of solids) is covered. Both valence band and core-level spectra, as well as a few cases of photon excited Auger electron spectroscopy, are employed in the investigations to derive information on N(E). The effect of several modulations inherent in the measured I(E)'s, such as final state band structure, cross section, and relaxation, is discussed. Examples of many-electron interactions in PES are given. Some experimental aspects of PES and AES studies are given with emphasis on sample preparation techniques. Multiple splitting of core levels is examined using the Mn levels in MnF/sub 2/ as a detailed case study. Core level splittings in transition metals, rare earth metals, transition metal halides and several alloys are also reported. The application of PES to the study of the chemical bond in some crystalline semiconductors and insulators, A/sup N/B/sup 8-N/ and A/sup N/B/sup 10-N/ compounds is treated, and a spectroscopic scale of ionicity for these compounds is developed from the measured ''s-band'' splitting in the valence band density of states. (GHT)

  2. Tracking electron-induced carbon contamination and cleaning of Ru surfaces by Auger electron spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Kanjilal, Aloke; Catalfano, Mark; Harilal, Sivanandan S.; Hassanein, Ahmed; Rice, Bryan [Center for Materials under Extreme Environment, School of Nuclear Engineering, Purdue University, West Lafayette, Indiana 47907 (United States); SEMATECH Inc., Albany, New York 12203 (United States)

    2012-07-15

    Extreme ultraviolet (EUV) radiation induced growth of carbon and oxygen desorption were investigated on a Ru surface by Auger electron spectroscopy (AES) in the presence and absence of additional photoelectrons (PEs) from a focusing Ru mirror. A decrease in EUV reflectivity with carbon growth in the presence of additional PEs has been observed. Conversely, a carbonaceous Ru surface was cleaned in sequential AES, and discussed in terms of secondary electron assisted dissociation of residual hydrocarbons and water molecules, followed by a chemical reaction between adsorbed carbon and oxygen atoms.

  3. Scanning Auger Electron Microscope

    Data.gov (United States)

    Federal Laboratory Consortium — A JEOL model 7830F field emission source, scanning Auger microscope.Specifications / Capabilities:Ultra-high vacuum (UHV), electron gun range from 0.1 kV to 25 kV,...

  4. The characterisation of non-evaporable getters by Auger electron spectroscopy Analytical potential and artefacts

    CERN Document Server

    Scheuerlein, C; Taborelli, M

    2002-01-01

    The surfaces of getter materials are particularly difficult to analyse because of their high chemical reactivity. The results obtained can be strongly influenced by the experimental set-up and procedures. In this paper the experimental influence on the Auger electron spectroscopy results is discussed, based on the measurements of more than 100 different non-evaporable getter (NEG) materials. There are four typical changes in the Auger electron spectra when a NEG becomes activated. The oxygen peak intensity decreases, the shape of the metal peaks changes, the carbon peak shape changes shape and intensity and a chlorine peak occurs. All these changes are affected by instrumental artefacts. The Zr-MNV peak shape changes occurring during the reduction of ZrO2 are well suited to determine the onset of NEG activation, while the slope with which the O-KLL peak intensity decreases in a certain temperature range is a better criterion for the determination of the temperature at which activation is complete. The O-KLL i...

  5. Growth of cobalt ultra-thin films deposited on Pt(100) surfaces: An Auger electron spectroscopy study

    Science.gov (United States)

    Boeglin, C.; Carrière, B.; Deville, J. P.; Heckmann, O.; Leroux, C.; Panissod, P.

    1989-04-01

    To investigate the possibility of building Co/Pt modulated multilayers, attention has been paid to the early stages of interface formation between cobalt and platinum. The growth of cobalt layers less than 10 monolayers thick on Pt(100) surfaces has been studied by Auger electron spectroscopy. Growth kinetics obtained by AES show that two different models of interface formation can be possible: the Volmer-Weber case (cobalt islands) or an interdiffusion process between the two metals (similar to suicide formation). Looking at the fine structure of the low-energy platinum Auger transitions suggests that there is a strong interaction between cobalt and platinum as soon as the equivalent of a cobalt 2 monolayer coverage is deposited. This would favor the interdiffusion process model.

  6. Auger electron spectroscopy study of initial stages of oxidation in a copper - 19.6-atomic-percent-aluminum alloy

    Science.gov (United States)

    Ferrante, J.

    1973-01-01

    Auger electron spectroscopy was used to examine the initial stages of oxidation of a polycrystalline copper - 19.6 a/o-aluminum alloy. The growth of the 55-eV aluminum oxide peak and the decay of the 59-, 62-, and 937-eV copper peaks were examined as functions of temperature, exposure, and pressure. Pressures ranged from 1x10 to the minus 7th power to 0.0005 torr of O2. Temperatures ranged from room temperature to 700 C. A completely aluminum oxide surface layer was obtained in all cases. Complete disappearance of the underlying 937-eV copper peak was obtained by heating at 700 C in O2 at 0.0005 torr for 1 hr. Temperature studies indicated that thermally activated diffusion was important to the oxidation studies. The initial stages of oxidation followed a logarithmic growth curve.

  7. Thermal effects in equilibrium surface segregation in a copper/10-atomic-percent-aluminum alloy using Auger electron spectroscopy

    Science.gov (United States)

    Ferrante, J.

    1972-01-01

    Equilibrium surface segregation of aluminum in a copper-10-atomic-percent-aluminum single crystal alloy oriented in the /111/ direction was demonstrated by using Auger electron spectroscopy. This crystal was in the solid solution range of composition. Equilibrium surface segregation was verified by observing that the aluminum surface concentration varied reversibly with temperature in the range 550 to 850 K. These results were curve fitted to an expression for equilibrium grain boundary segregation and gave a retrieval energy of 5780 J/mole (1380 cal/mole) and a maximum frozen-in surface coverage three times the bulk layer concentration. Analyses concerning the relative merits of sputtering calibration and the effects of evaporation are also included.

  8. Auger electron spectroscopy study of oxidation of a PdCr alloy used for high-temperature sensors

    Science.gov (United States)

    Boyd, Darwin L.; Zeller, Mary V.; Vargas-Aburto, Carlos

    1993-01-01

    A Pd-13 wt. percent Cr solid solution is a promising high-temperature strain gage alloy. In bulk form it has a number of properties that are desirable in a resistance strain gage material, such as a linear electrical resistance versus temperature curve to 1000 C and stable electrical resistance in air at 1000 C. However, unprotected fine wire gages fabricated from this alloy perform well only to 600 C. At higher temperatures severe oxidation degrades their electrical performance. In this work Auger electron spectroscopy was used to study the oxidation chemistry of the alloy wires and ribbons. Results indicate that the oxidation is caused by a complex mechanism that is not yet fully understood. As expected, during oxidation, a layer of chromium oxide is formed. This layer, however, forms beneath a layer of metallic palladium. The results of this study have increased the understanding of the oxidation mechanism of Pd-13 wt. percent Cr.

  9. Interaction of oxygen with an AISI 314 stainless steel surface studied by ellipsometry and auger electron spectroscopy in combination with ion bombardment

    NARCIS (Netherlands)

    Stokkers, G.J.; van Silfhout, Arend; Bootsma, G.A.; Fransen, T.; Gellings, P.J.

    1983-01-01

    The influence of pretreatment (ion bombardment) on the initial oxidation of AISI 314 stainless steel has been investigated in ultra high vacuum systems with ellipsometry and Auger electron spectroscopy. The bombardment was carried out with Ar+ ions with energies up to 2.2 keV at various doses and

  10. Study of O/Ni(100) with LEED (low-energy electron diffraction) and AES (auger electron spectroscopy) from chemisorption to oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Wen-Di.

    1990-11-16

    The structures formed on the Ni(100) surface during oxygen adsorption, leading to oxidation, are studied with Video-LEED (low-energy electron diffraction) and AES (Auger electron spectroscopy). The temperature- and exposure-dependence in the development of LEED patterns observed during oxidation of Ni(100), at oxidation temperatures of 80 to 400 K, are investigated extensively. Integrated diffraction spot intensities and fractional spot profiles are measured quantitatively and continuously, allowing unambiguous correlation of various surface processes. AES is used to measure the oxidation onset during adsorption and the final relative thickness of the oxide. 48 figs., 79 refs.

  11. High dose implantation of nitrogen in tool steel: Auger electron spectroscopy and hardness measurements

    Energy Technology Data Exchange (ETDEWEB)

    Bredell, L.J. (Dept. of Physics, Univ. of Pretoria (South Africa)); Malherbe, J.B. (Dept. of Physics, Univ. of Pretoria (South Africa))

    1993-05-15

    Tool stell samples were implanted with 100 keV N[sup +] ions at liquid nitrogen temperature to doses of 3 x 10[sup 17] and 1 x 10[sup 18] cm[sup -2]. Only the dose of 1 x 10[sup 18] cm[sup -2] caused a significant hardening effect. Two mechanisms contributed to this hardness increase, namely nitride formation and radiation damage. Cooling during implantation caused additional hardening, owing to a martensitic phase transformation. The projected range (R[sub p] = 110 nm) for the implanted species was obtained by Auger sputter depth profiling. If the hardened layer thickness was taken as 2R[sub p], then the Joensson-Hogmark model gave an average hardness value of 2010 HV for the implanted layer. However, a more realistic value of 900 HV was calculated under the assumption that typical radiation damage profiles (R[sub d] = 3R[sub p]) contributed to the hard film thickness. It is difficult to judge the accuracy of the model for predicting the correct absolute hardness of the implanted layer but it is shown that deep radiation-induced damage plays a major role in surface hardening. (orig.)

  12. Modification to an Auger Electron Spectroscopy system for measuring segregation in a bi-crystal

    CSIR Research Space (South Africa)

    Jafta, CJ

    2013-03-01

    Full Text Available to the scanning control unit of the AES electron beam to eliminate the difference in experimental parameters and specialized written software to automate the data acquisition process. This makes direct comparison of segregation parameters on two different...

  13. Nanodosimetry of (125)I Auger electrons.

    Science.gov (United States)

    Bantsar, Aliaksandr; Pszona, Stanislaw

    2012-12-01

    The nanodosimetric description of the radiation action of Auger electrons on nitrogen targets of nanometric size is presented. Experimental microdosimetry at nanometer scale for Auger electrons has been accomplished with the set-up called Jet Counter. This consists of a pulse-operated valve which injects an expanding nitrogen jet into an interaction chamber where a gaseous sensitive volume of cylindrical shape is created. The ionization cluster size distributions (ICSD) created by Auger electrons emitted by (125)I while crossing a nanometer-sized volume have been measured. The ICSD for the sensitive volumes corresponding to 3 and 12 nm in diameter (in unit density 1 g/cm(3)) irradiated by electrons emitted by a (125)I source were collected and compared with the corresponding Monte Carlo (MC) simulation. The preliminary results of the experiments with Auger electrons of (125)I interacting with a nitrogen jet having nanometric size comparable to a deoxyribonucleic acid (DNA) and nucleosome, showing the discrete spectrum of ICSD with extended cluster size, are described. The presented paper describes for the first time the nanodosimetric experiments with Auger electrons emitted by (125)I. A set of the new descriptors of the radiation quality describing the radiation effect at nanometer level is proposed. The ICSD were determined for the first time for an Auger emitter of (125)I.

  14. The Effect of Stress in the Density of States of Amorphous Carbon Films Determined by X-Ray Excited Auger Electron Spectroscopy

    Directory of Open Access Journals (Sweden)

    P. F. Barbieri

    2017-01-01

    Full Text Available Amorphous carbon films can be prepared with a large variety of structure and have been used in a number of technological applications. Many of their properties have been determined, but very little is known concerning the effect of pressure on their properties. In this work we investigate the influence of pressure of graphite-like amorphous carbon films on the density of states (DOS using X-ray Excited Auger Electron Spectroscopy (XAES and the second derivate method of the XAES. The films were deposited by ion beam deposition and simultaneously bombarded with argon, which is responsible for the variation of the film stress, reaching extremely high values (4.5 GPa. Marked variations of the density of states of the pπ, pσ, sp, and s components were observed with increasing stress.

  15. DESORPTION OF Te CAPPING LAYER FROM ZnTe (100: AUGER SPECTROSCOPY, LOW-ENERGY ELECTRON DIFFRACTION AND SCANNING TUNNELING MICROSCOPY

    Directory of Open Access Journals (Sweden)

    K. K. Sossoe

    2016-01-01

    Full Text Available The influence of the annealing temperature to desorb a protective Te capping layer of the zinc telluride (ZnTe (100 surface was investigated. The surface reconstruction of the ZnTe (100 upon the removal of a Te capping layer grown by the molecular beam epitaxy was characterized by different methods. Auger spectroscopy brought out the chemical composition of the surface before and after annealing; the Low-energy electron diffraction (LEED gave information about the crystallographic structure. The surface crystallographic configurations of tellurium Te (c (2x2 and Te (c (2x1 are confirmed by scanning tunneling microscopy (STM. Such a study reveals a phase transition from a rich-Te to a poor-Te surface as the annealing temperature increases. 

  16. Electronic spectroscopies

    NARCIS (Netherlands)

    Weckhuysen, B.M.; Schoonheydt, R.A.

    2000-01-01

    Diffuse reflectance spectroscopy (DRS) in the ultraviolet, visible and near-infrared region is a versatile spectroscopic technique, as both d-d and charge transfer transitions of supported TMI can be probed. One of the advantages of electronic spectroscopy is that the obtained information is

  17. Auger electron spectroscopy study of surface segregation in the binary alloys copper-1 atomic percent indium, copper-2 atomic percent tin, and iron-6.55 atomic percent silicon

    Science.gov (United States)

    Ferrante, J.

    1973-01-01

    Auger electron spectroscopy was used to examine surface segregation in the binary alloys copper-1 at. % indium, copper-2 at. % tin and iron-6.55 at. % silicon. The copper-tin and copper-indium alloys were single crystals oriented with the /111/ direction normal to the surface. An iron-6.5 at. % silicon alloy was studied (a single crystal oriented in the /100/ direction for study of a (100) surface). It was found that surface segregation occurred following sputtering in all cases. Only the iron-silicon single crystal alloy exhibited equilibrium segregation (i.e., reversibility of surface concentration with temperature) for which at present we have no explanation. McLean's analysis for equilibrium segregation at grain boundaries did not apply to the present results, despite the successful application to dilute copper-aluminum alloys. The relation of solute atomic size and solubility to surface segregation is discussed. Estimates of the depth of segregation in the copper-tin alloy indicate that it is of the order of a monolayer surface film.

  18. Ultrafast dynamics of multiple exciton harvesting in the CdSe-ZnO system: electron injection versus Auger recombination.

    Science.gov (United States)

    Zídek, Karel; Zheng, Kaibo; Abdellah, Mohamed; Lenngren, Nils; Chábera, Pavel; Pullerits, Tõnu

    2012-12-12

    We study multiple electron transfer from a CdSe quantum dot (QD) to ZnO, which is a prerequisite for successful utilization of multiple exciton generation for photovoltaics. By using ultrafast time-resolved spectroscopy we observe competition between electron injection into ZnO and quenching of multiexcitons via Auger recombination. We show that fast electron injection dominates over biexcitonic Auger recombination and multiple electrons can be transferred into ZnO. A kinetic component with time constant of a few tens of picoseconds was identified as the competition between injection of the second electron from a doubly excited QD and a trion Auger recombination. Moreover, we demonstrate that the multiexciton harvesting efficiency changes significantly with QD size. Within a narrow QD diameter range from 2 to 4 nm, the efficiency of electron injection from a doubly excited QD can vary from 30% to 70% in our system.

  19. Chemical-state imaging of Li using scanning Auger electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Ishida, Nobuyuki, E-mail: ISHIDA.Nobuyuki@nims.go.jp [Global Research Center for Environment and Energy based on Nanomaterials Science (GREEN), National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan); Fujita, Daisuke [Global Research Center for Environment and Energy based on Nanomaterials Science (GREEN), National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan); Advanced Nanocharacterization Unit, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan)

    2013-02-15

    Highlights: •Scanning Auger electron microscopy is used to image chemical states of Li. •The combined use of AES and EELS signals for the elemental mapping is powerful. •Distribution corresponding to metallic and oxidized states of Li can be imaged. -- Abstract: The demand for measurement tools to detect Li with high spatial resolution and precise chemical sensitivity is increasing with the spread of lithium-ion batteries (LIBs) for use in a wide range of applications. In this work, scanning Auger electron microscopy (SAM) is used to image chemical states of a partially oxidized Li surface on the basis of the Auger electron spectroscopy (AES) and electron energy loss spectroscopy (EELS) data obtained during an oxidation process of a metal Li. We show that distribution of metallic and oxidized states of Li is clearly imaged by mapping the intensity of the corresponding AES and EELS peaks. Furthermore, a tiny difference in the extent of oxidation can be distinguished by comparing the elemental map of an AES peak with that of an EELS peak owing to the different behaviors of those signals to the chemical states of Li.

  20. A stochastic cascade model for Auger-electron emitting radionuclides.

    Science.gov (United States)

    Lee, Boon Q; Nikjoo, Hooshang; Ekman, Jörgen; Jönsson, Per; Stuchbery, Andrew E; Kibédi, Tibor

    2016-11-01

    To benchmark a Monte Carlo model of the Auger cascade that has been developed at the Australian National University (ANU) against the literature data. The model is applicable to any Auger-electron emitting radionuclide with nuclear structure data in the format of the Evaluated Nuclear Structure Data File (ENSDF). Schönfeld's algorithms and the BrIcc code were incorporated to obtain initial vacancy distributions due to electron capture (EC) and internal conversion (IC), respectively. Atomic transition probabilities were adopted from the Evaluated Atomic Data Library (EADL) for elements with atomic number, Z = 1-100. Atomic transition energies were evaluated using a relativistic Dirac-Fock method. An energy-restriction protocol was implemented to eliminate energetically forbidden transitions from the simulations. Calculated initial vacancy distributions and average energy spectra of (123)I, (124)I, and (125)I were compared with the literature data. In addition, simulated kinetic energy spectra and frequency distributions of the number of emitted electrons and photons of the three iodine radionuclides are presented. Some examples of radiation spectra of individual decays are also given. Good agreement with the published data was achieved except for the outer-shell Auger and Coster-Kronig transitions. Nevertheless, the model needs to be compared with experimental data in a future study.

  1. Site-specific Auger electron spectra of ethyl trifluoroacelate molecules studied by magnetic bottle electron spectrometer

    Science.gov (United States)

    Iwayama, Hiroshi; Shigemasa, Eiji; Hikosaka, Yasumasa; Nakano, Motoyoshi; Ito, Kenji; Lablanquie, Pascal; Penet, Francis; Andric, Lidija; Selles, Patricia

    2012-11-01

    We performed multielectron coincidence measurements for inner-shell photoionizations of ethyl trifluoroacelate molecules (C4H5F3O2) using a magnetic bottle electron spectrometer. From a two dimensional coincidence map between a photoelectron and Auger electron for C 1s ionizations, we extracted site-specific Auger electron spectra for each carbon site and corresponding binding energy of doubly charged states.

  2. High energy resolution and first time-dependent positron annihilation induced Auger electron spectroscopty

    Energy Technology Data Exchange (ETDEWEB)

    Mayer, Jakob

    2010-04-03

    It was the aim of this thesis to improve the existing positron annihilation induced Auger spectrometer at the highly intense positron source NEPOMUC (NEutron induced POsitron source MUniCh) in several ways: Firstly, the measurement time for a single spectrum should be reduced from typically 12 h to roughly 1 h or even less. Secondly, the energy resolution, which amounted to {delta}E/E{approx}10%, should be increased by at least one order of magnitude in order to make high resolution positron annihilation induced Auger spectroscopy (PAES)-measurements of Auger transitions possible and thus deliver more information about the nature of the Auger process. In order to achieve these objectives, the PAES spectrometer was equipped with a new electron energy analyzer. For its ideal operation all other components of the Auger analysis chamber had to be adapted. Particularly the sample manipulation and the positron beam guidance had to be renewed. Simulations with SIMION {sup registered} ensured the optimal positron lens parameters. After the adjustment of the new analyzer and its components, first measurements illustrated the improved performance of the PAES setup: Firstly, the measurement time for short overview measurements was reduced from 3 h to 420 s. The measurement time for more detailed Auger spectra was shortened from 12 h to 80 min. Secondly, even with the reduced measurement time, the signal to noise ratio was also enhanced by one order of magnitude. Finally, the energy resolution was improved to {delta}E/E < 1. The exceptional surface sensitivity and elemental selectivity of PAES was demonstrated in measurements of Pd and Fe, both coated with Cu layers of varying thickness. PAES showed that with 0.96 monolayer of Cu on Fe, more than 55% of the detected Auger electrons stem from Cu. In the case of the Cu coated Pd sample 0.96 monolayer of Cu resulted in a Cu Auger fraction of more than 30% with PAES and less than 5% with electron induced Auger spectroscopy

  3. Auger Spectroscopy Analysis of Spalled LEU-10Mo Foils

    Energy Technology Data Exchange (ETDEWEB)

    Lawrence, Samantha Kay [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Schulze, Roland K. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-08-03

    Presentation includes slides on Surface Science used to probe LEU-10Mo Spall; Auger highlights graphitic-like inclusions and Mo-deficient oxide on base metal; Higher C concentration detected within spall area Images Courtesy; Depth profiling reveals thick oxide; Mo concentration nears nominal only at depths ~400 nm; and lastly Key Findings.

  4. Analytical Chemistry of Surfaces: Part II. Electron Spectroscopy.

    Science.gov (United States)

    Hercules, David M.; Hercules, Shirley H.

    1984-01-01

    Discusses two surface techniques: X-ray photoelectron spectroscopy (ESCA) and Auger electron spectroscopy (AES). Focuses on fundamental aspects of each technique, important features of instrumentation, and some examples of how ESCA and AES have been applied to analytical surface problems. (JN)

  5. Evaluating 99mTc Auger electrons for targeted tumor radiotherapy by computational methods.

    Science.gov (United States)

    Tavares, Adriana Alexandre S; Tavares, João Manuel R S

    2010-07-01

    Technetium-99m (99mTc) has been widely used as an imaging agent but only recently has been considered for therapeutic applications. This study aims to analyze the potential use of 99mTc Auger electrons for targeted tumor radiotherapy by evaluating the DNA damage and its probability of correct repair and by studying the cellular kinetics, following 99mTc Auger electron irradiation in comparison to iodine-131 (131I) beta minus particles and astatine-211 (211At) alpha particle irradiation. Computational models were used to estimate the yield of DNA damage (fast Monte Carlo damage algorithm), the probability of correct repair (Monte Carlo excision repair algorithm), and cell kinetic effects (virtual cell radiobiology algorithm) after irradiation with the selected particles. The results obtained with the algorithms used suggested that 99mTc CKMMX (all M-shell Coster-Kroning--CK--and super-CK transitions) electrons and Auger MXY (all M-shell Auger transitions) have a therapeutic potential comparable to high linear energy transfer 211At alpha particles and higher than 131I beta minus particles. All the other 99mTc electrons had a therapeutic potential similar to 131I beta minus particles. 99mTc CKMMX electrons and Auger MXY presented a higher probability to induce apoptosis than 131I beta minus particles and a probability similar to 211At alpha particles. Based on the results here, 99mTc CKMMX electrons and Auger MXY are useful electrons for targeted tumor radiotherapy.

  6. Direct measurement of Auger electrons emitted from a semiconductor light-emitting diode under electrical injection: identification of the dominant mechanism for efficiency droop.

    Science.gov (United States)

    Iveland, Justin; Martinelli, Lucio; Peretti, Jacques; Speck, James S; Weisbuch, Claude

    2013-04-26

    We report on the unambiguous detection of Auger electrons by electron emission spectroscopy from a cesiated InGaN/GaN light-emitting diode under electrical injection. Electron emission spectra were measured as a function of the current injected in the device. The appearance of high energy electron peaks simultaneously with an observed drop in electroluminescence efficiency shows that hot carriers are being generated in the active region (InGaN quantum wells) by an Auger process. A linear correlation was measured between the high energy emitted electron current and the "droop current"--the missing component of the injected current for light emission. We conclude that the droop phenomenon in GaN light-emitting diodes originates from the excitation of Auger processes.

  7. Pierre Auger and Lise Meitner, respective contribution to the Auger effect; Pierre Auger et Lise Meitner comparaison de leurs contributions a l'effet Auger

    Energy Technology Data Exchange (ETDEWEB)

    Hardoin Duparc, O. [Ecole Polytechnique, Unite mixte de Physique, CNRS/CEA/W LSI, 91 - Palaiseau (France)

    2010-03-15

    Whenever an incident energetic particle (X ray, gamma or electron) ejects an electron from a deep shell in the electronic cloud, a more external electron goes to this level to fill the hole. The extra energy can be emitted either as X ray (X ray fluorescence) or as an electron called Auger electron. The ratio between these 2 possibilities depends on the charge number of the atom. For atoms lighter than gadolinium the ejection of an Auger electron is more likely. The energy of the Auger electron depends only on the nature of the atom and not on the energy of the incident particle. This feature is the basis of the Auger electron spectroscopy. Lise Meitner observed and described the 'Auger effect' a few month before Pierre Auger did, but it was in the context of an erroneous interpretation of beta spectra. Pierre Auger worked on an improved cloud chamber able to visualized the complete event: first the production of a photoelectron, then the emission of a ray quantum and the absorption of this quantum by the atom followed by the emission of an electron. Auger claimed to have observed up to 3 successive Auger effects in iodine. (A.C.)

  8. Attosecond streaking of shake-up and Auger electrons in xenon

    Directory of Open Access Journals (Sweden)

    Drescher M.

    2013-03-01

    Full Text Available We present first results of simultaneous attosecond streaking measurements of shake-up electrons and Auger electrons emitted from xenon. We extract relative photo-emission delays for electrons emitted from the 4d, 5s and 5p subshell, as well as for the 5p−25d correlation satellite (shake-up electrons.

  9. Determination of the solid angle and response function of a hemispherical spectrograph with injection lens for Auger electrons emitted from long lived projectile states.

    Science.gov (United States)

    Doukas, S; Madesis, I; Dimitriou, A; Laoutaris, A; Zouros, T J M; Benis, E P

    2015-04-01

    We present SIMION 8.1 Monte Carlo type simulations of the response function and detection solid angle for long lived Auger states (lifetime τ ∼ 10(-9) - 10(-5) s) recorded by a hemispherical spectrograph with injection lens and position sensitive detector used for high resolution Auger spectroscopy of ion beams. Also included in these simulations for the first time are kinematic effects particular to Auger emission from fast moving projectile ions such as line broadening and solid angle limitations allowing for a more accurate and realistic line shape modeling. Our results are found to be in excellent agreement with measured electron line shapes of both long lived 1s2s2p(4)P and prompt Auger projectile states formed by electron capture in collisions of 25.3 MeV F(7+) with H2 and 12.0 MeV C(4+) with Ne recorded at 0° to the beam direction. These results are important for the accurate evaluation of the 1s2s2p (4)P/(2)P ratio of K-Auger cross sections whose observed non-statistical production by electron capture into He-like ions, recently a field of interesting interpretations, awaits further resolution.

  10. Chirped Auger electron emission due to field-assisted post-collision interaction

    Directory of Open Access Journals (Sweden)

    Bonitz M.

    2013-03-01

    Full Text Available We have investigated the Auger decay in the temporal domain by applying a terahertz streaking light field. Xenon and krypton atoms were studied by implementing the free-electron laser in Hamburg (FLASH as well as a source of high-order harmonic radiation combined with terahertz pulses from an optical rectification source. The observed linewidth asymmetries in the streaked spectra suggest a chirped Auger electron emission which is understood in terms of field-assisted post-collision interaction. The experimentally obtained results agree well with model calculations.

  11. Surgery of fast, highly charged ions studied by zero-degree Auger spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Stolterfoht, N.; Miller, P.D.; Krause, H.F.; Yamazaki, Y.; Swenson, J.K.; Bruch, R.; Dittner, P.F.; Pepmiller, P.L.; Datz, S.

    1986-01-01

    Zero-degree Auger spectra were measured in collisions of oxygen and carbon on He with incident charge states of q = 2 to 5 and for energies from 5 to 30 MeV. Since the light target particle He acts selectively on the projectile ion, we refer to the present method as ion surgery. Apart from the one-electron processes single excitation and single loss, two-electron processes such as transfer excitation and transfer loss are studied. 17 refs., 4 figs., 1 tab.

  12. Electronic Spectroscopy & Dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Mark Maroncelli, Nancy Ryan Gray

    2010-06-08

    The Gordon Research Conference (GRC) on Electronic Spectroscopy and Dynamics was held at Colby College, Waterville, NH from 07/19/2009 thru 07/24/2009. The Conference was well-attended with participants (attendees list attached). The attendees represented the spectrum of endeavor in this field coming from academia, industry, and government laboratories, both U.S. and foreign scientists, senior researchers, young investigators, and students. The GRC on Electronic Spectroscopy & Dynamics showcases some of the most recent experimental and theoretical developments in electronic spectroscopy that probes the structure and dynamics of isolated molecules, molecules embedded in clusters and condensed phases, and bulk materials. Electronic spectroscopy is an important tool in many fields of research, and this GRC brings together experts having diverse backgrounds in physics, chemistry, biophysics, and materials science, making the meeting an excellent opportunity for the interdisciplinary exchange of ideas and techniques. Topics covered in this GRC include high-resolution spectroscopy, biological molecules in the gas phase, electronic structure theory for excited states, multi-chromophore and single-molecule spectroscopies, and excited state dynamics in chemical and biological systems.

  13. Electron Paramagnetic Resonance Spectroscopy

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 20; Issue 11. Electron Paramagnetic Resonance Spectroscopy: Biological Applications. B G Hegde. General Article Volume 20 Issue 11 November 2015 pp 1017-1032. Fulltext. Click here to view fulltext PDF. Permanent link:

  14. The KLM + KLN Auger electron spectrum of rubidium in different matrices

    Science.gov (United States)

    Inoyatov, A. Kh; Kovalík, A.; Perevoshchikov, L. L.; Filosofov, D. V.; Vénos, D.; Lee, B. Q.; Ekman, J.; Baimukhanova, A.

    2017-08-01

    The KLM + KLN Auger electron spectrum of rubidium (Z = 37) emitted in the electron capture decay of radioactive 83Sr in a polycrystalline platinum matrix and also 85Sr in polycrystalline platinum and carbon matrices as well as in an evaporated layer onto a carbon backing were experimentally studied in detail for the first time using a combined electrostatic electron spectrometer. Energies, relative intensities, and natural widths of fifteen basic spectrum components were determined and compared with both theoretical predictions and experimental data for krypton (Z = 36). Relative spectrum line energies obtained from the semi-empirical calculations in intermediate coupling scheme were found to agree within 3σ with the measured values while disagreement with experiment exceeding 3σ was often observed for values obtained from our multiconfiguration Dirac-Hartree-Fock calculations. The absolute energy of the dominant spectrum component given by the semi-empirical approach agrees within 1σ with the measured value. Shifts of +(0.2 ± 0.2) and -(1.9 ± 0.2) eV were measured for the dominant KLM spectrum components between the 85Sr sources prepared by vacuum evaporation on and implanted into the carbon foil, respectively, relative to 85Sr implanted into the platinum foil. A value of (713 ± 2) eV was determined for the energy difference of the dominant components of the KLM + KLN Auger electron spectra of rubidium and krypton generated in the polycrystalline platinum matrix. From the detailed analysis of the measured data and available theoretical results, the general conclusion can be drawn that the proper description of the KLM + KLN Auger electron spectrum for Z around 37 should still be based on the intermediate coupling of angular momenta taking into account relativistic effects.

  15. Observation of fine structure in auger electron spectra for chemical state analysis. Auger denshi bunko ho ni yoru jotai bunseki no tame no spectrum bisai kozo kansatsu

    Energy Technology Data Exchange (ETDEWEB)

    Hirokawa, K. (Tohoku Univ., Sendai (Japan). Inst. for Materials Research); Fukuda, Y. (Shizuoka Univ., Shizuoka (Japan). Research Inst. of Electronics); Suzuki, K. (Nippon Steel Corp., Tokyo (Japan)); Hashimoto, S. (NKK Corp., Tokyo (Japan)); Suzuki, T. (Kawasaki Steel Corp., Kobe (Japan)); Usuki, N. (Sumotomo Metal Industries, Ltd., Osaka (Japan)); Gennai, N. (Kobelco Research Inst., Inc., Kobe (Japan)); Yoshida, S. (Daido Steel Co. Ltd., Nagoya (Japan)); Koda, M. (Nisshin Steel Co. Ltd., Tokyo (Japan)); Sezaki, H. (Hitachi Metals, Ltd., Tokyo (Japan)); Horie, H. (Kyushu Electronic Metal Co. Ltd., Fukuoka (Japan)); Tanaka, A. (ULVAC-PHI Incorporated, Kanagawa (Japan)); Otsubo, T. (The Japan Iron and Steel Federation, Tokyo (Japan))

    1991-09-01

    Cooperative researches by participation of 8 analytical laboratories such as Institute for Materials Research, Tohoku University and Steel Research Center, NKK Corporation, etc. were conducted wherein the common samples of Au, Fe, Ni, Al and their oxides were measured by means of Auger electron spectra. By virtue of an elastic scattering peak apparatus and the standardization of the sample locations, peak energy values of Auger electron spectra obtained by the respective equipment are neutrally in good agreement. Auger profiles (peak intensity) considerably change according to the respective units and the measuring conditions. When the spectra are as sharp as in LMM, LMV and LVV of Fe, Ni and their oxides, and emerge, as in the case of LMM and LMV, in mutually close energy value, the difference in the ratio of spectrum intensity by the respective machines and measuring methods is small in metal oxides, but, in the case of LVV LMM, the state analysis can be made by its slight change. 10 refs., 9 figs., 1 tab.

  16. Features of atomic images reconstructed from photoelectron, Auger electron, and internal detector electron holography using SPEA-MEM

    Energy Technology Data Exchange (ETDEWEB)

    Matsushita, Tomohiro, E-mail: matusita@spring8.or.jp [Japan Synchrotron Radiation Research Institute, SPring-8, Sayo, Hyogo 679-5198 (Japan); Matsui, Fumihiko [Graduate School of Materials Science, Nara Institute of Science and Technology, Ikoma, Nara 630-0192 (Japan)

    2014-08-15

    Highlights: • We develop a 3D atomic image reconstruction algorithm for photoelectron, Auger electron, and internal detector holography. • We examine the shapes of the atomic images reconstructed by using a developed kernel function. • We examine refraction effect at surface, limitation effect of the hologram data, energy resolution effect, and angular resolution effect. • These discussions indicate the experimental requirements to obtain the clear 3D atomic image. - Abstract: Three-dimensional atomic images can be reconstructed from photoelectron, Auger electron, and internal detector electron holograms using a scattering pattern extraction algorithm using the maximum entropy method (SPEA-MEM) that utilizes an integral transform. An integral kernel function for the integral transform is the key to clear atomic image reconstruction. We composed the kernel function using a scattering pattern function and estimated its ability. Image distortion caused by multiple scattering was also evaluated. Four types of Auger electron wave functions were investigated, and the effect of these wave function types was estimated. In addition, we addressed refraction at the surface, the effects of data limitation, and energy and angular resolutions.

  17. New electronics for the surface detectors of the Pierre Auger Observatory

    Energy Technology Data Exchange (ETDEWEB)

    Kleifges, M., E-mail: Matthias.Kleifges@kit.edu [Karlsruhe Institute of Technology – Institute for Data Processing and Electronics, Karlsruhe (Germany)

    2016-07-11

    The Pierre Auger Observatory is the largest installation worldwide for the investigation of ultra-high energy cosmic rays. Air showers are detected using a hybrid technique with 27 fluorescence telescopes and 1660 water-Cherenkov detectors (WCD) distributed over about 3000 km{sup 2}. The Auger Collaboration has decided to upgrade the electronics of the WCD and complement the surface detector with scintillators (SSD). The objective is to improve the separation between the muonic and the electron/photon shower component for better mass composition determination during an extended operation period of 8–10 years. The surface detector electronics records data locally and generates time stamps based on the GPS timing. The performance of the detectors is significantly improved with a higher sampling rate, an increased dynamic range, new generation of GPS receivers, and FPGA integrated CPU power. The number of analog channels will be increased to integrate the new SSD, but the power consumption needs to stay below 10 W to be able to use the existing photovoltaic system. In this paper, the concept of the additional SSD is presented with a focus on the design and performance of the new surface detector electronics.

  18. Accelerator based production of auger-electron-emitting isotopes for radionuclide therapy

    Energy Technology Data Exchange (ETDEWEB)

    Thisgaard, H.

    2008-08-15

    In this research project the focus has been on the identification and production of new, unconventional Auger-electron-emitting isotopes for targeted radionuclide therapy of cancer. Based on 1st principles dosimetry calculations on the subcellular level, the Auger-emitter 119Sb has been identified as a potent candidate for therapy. The corresponding imaging analogue 117Sb has been shown from planar scintigraphy and single-photon emission computed tomography (SPECT) to be suitable for SPECT-based dosimetry of a future Sb-labeled radiopharmaceutical. The production method of these radioisotopes has been developed using a low-energy cyclotron via the nuclear reactions 119Sn(p,n)119Sb and 117Sn(p,n)117Sb including measurements of the excitation function for the former reaction. Moreover, a new high-yield radiochemical separation method has been developed to allow the subsequent separation of the produced 119Sb from the enriched 119Sn target material with high radionuclidic- and chemical purity. A method that also allows efficient recovery of the 119Sn for recycling. To demonstrate the ability of producing therapeutic quantities of 119Sb and other radioisotopes for therapy with a low-energy cyclotron, two new 'High Power' cyclotron targets were developed in this study. The target development was primarily based on theoretical thermal modeling calculations using finite-element-analysis software. With these targets, I have shown that it will be possible to produce several tens of GBq of therapeutics isotopes (e.g. 119Sb or 64Cu) using the PETtrace cyclotron commonly found at the larger PET-centers in the hospitals. Finally, research in a new method to measure the radiotoxicity of Auger-emitters invitro using cellular microinjection has been carried out. The purpose of this method is to be able to experimentally evaluate and compare the potency of the new and unconventional Auger-emitters (e.g. 119Sb). However, due to experimental complications, the development

  19. {sup 99m}Tc Auger electrons - Analysis on the effects of low absorbed doses by computational methods

    Energy Technology Data Exchange (ETDEWEB)

    Tavares, Adriana Alexandre S., E-mail: adriana_tavares@msn.co [Faculdade de Engenharia da Universidade do Porto (FEUP), Rua Dr. Roberto Frias, S/N, 4200-465 Porto (Portugal); Tavares, Joao Manuel R.S., E-mail: tavares@fe.up.p [Faculdade de Engenharia da Universidade do Porto (FEUP), Rua Dr. Roberto Frias, S/N, 4200-465 Porto (Portugal)

    2011-03-15

    We describe here the use of computational methods for evaluation of the low dose effects on human fibroblasts after irradiation with Technetium-99m ({sup 99m}Tc) Auger electrons. The results suggest a parabolic relationship between the irradiation of fibroblasts with {sup 99m}Tc Auger electrons and the total absorbed dose. Additionally, the results on very low absorbed doses may be explained by the bystander effect, which has been implicated on the cell's effects at low doses. Further in vitro evaluation will be worthwhile to clarify these findings.

  20. Surface studies of praseodymium by electron spectroscopies

    Science.gov (United States)

    Krawczyk, Mirosław; Pisarek, Marcin; Lisowski, Wojciech; Jablonski, Aleksander

    2016-12-01

    Electron transport properties in praseodymium (Pr) foil samples were studied by elastic-peak electron spectroscopy (EPES). Prior to EPES measurements, the Pr sample surface was pre-sputtered by Ar ions with ion energy of 2-3 keV. After such treatment, the Pr sample still contained about 10 at.% of residual oxygen in the surface region, as detected by X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES) analyses. The inelastic mean free path (IMFP), characterizing electron transport within this region (4 nm-thick), was evaluated from EPES using both Ni and Au standards as a function of energy in the range of 0.5-2 keV. Experimental IMFPs, λ, were approximated by the simple function λ = kEp, where E is energy (in eV), and k = 0.1549 and p = 0.7047 were the fitted parameters. These values were compared with IMFPs for the praseodymium surface in which the presence of oxygen was tentatively neglected, and also with IMFPs resulting from the TPP-2M predictive equation for bulk praseodymium. We found that the measured IMFP values to be only slightly affected by neglect of oxygen in calculations. The fitted function applied here was consistent with the energy dependence of the EPES-measured IMFPs. Additionally, the measured IMFPs were found to be from 2% to 4.2% larger than the predicted IMFPs for praseodymium in the energy range of 500-1000 eV. For electron energies of 1500 eV and 2000 eV, there was an inverse correlation between these values, and then the resulting deviations of -0.4% and -2.7%, respectively, were calculated.

  1. Evaluation of DNA damage induced by Auger electrons from 137Cs.

    Science.gov (United States)

    Watanabe, Ritsuko; Hattori, Yuya; Kai, Takeshi

    2016-11-01

    To understand the biological effect of external and internal exposure from 137Cs, DNA damage spectrum induced by directly emitted electrons (γ-rays, internal conversion electrons, Auger electrons) from 137Cs was compared with that induced by 137Cs γ-rays. Monte Carlo track simulation method was used to calculate the microscopic energy deposition pattern in liquid water. Simulation was performed for the two simple target systems in microscale. Radiation sources were placed inside for one system and outside for another system. To simulate the energy deposition by directly emitted electrons from 137Cs placed inside the system, the multiple ejections of electrons after internal conversion were considered. In the target systems, induction process of DNA damage was modeled and simulated for both direct energy deposition and the water radical reaction on the DNA. The yield and spatial distribution of simple and complex DNA damage including strand breaks and base lesions were calculated for irradiation by electrons and γ-rays from 137Cs. The simulation showed that the significant difference in DNA damage spectrum was not caused by directly ejected electrons and γ-rays from 137Cs. The result supports the existing perception that the biological effects by internal and external exposure by 137Cs are equivalent.

  2. Use of a partial local density of states calculation to characterize the Auger electron Si-L2,3 VV transitions of thin oxide layers

    NARCIS (Netherlands)

    Sasse, A.G.B.M.; Wormeester, Herbert; van der Hoef, Martin Anton; Keim, Enrico G.; van Silfhout, Arend

    1989-01-01

    The line shape of the Si-L2,3 VV Auger spectrum is to a first approximation equal to the sum of the convolution products of the partial local density of states (pLDOS), each weighted by the two electron Auger matrix elements and the escape depth. Semiempirical quantum chemical cluster calculations

  3. Influence of host matrices on krypton electron binding energies and KLL Auger transition energies

    Energy Technology Data Exchange (ETDEWEB)

    Inoyatov, A.Kh., E-mail: inoyatov@jinr.ru [Laboratory of Nuclear Problems, JINR, Dubna, Moscow Region (Russian Federation); Institute of Applied Physics, National University, Tashkent, Republic of Uzbekistan (Uzbekistan); Perevoshchikov, L.L. [Laboratory of Nuclear Problems, JINR, Dubna, Moscow Region (Russian Federation); Kovalík, A. [Laboratory of Nuclear Problems, JINR, Dubna, Moscow Region (Russian Federation); Nuclear Physics Institute of the ASCR, CZ-25068 Řež near Prague (Czech Republic); Filosofov, D.V.; Yushkevich, Yu.V. [Laboratory of Nuclear Problems, JINR, Dubna, Moscow Region (Russian Federation); Ryšavý, M. [Nuclear Physics Institute of the ASCR, CZ-25068 Řež near Prague (Czech Republic); Lee, B.Q.; Kibédi, T.; Stuchbery, A.E. [Department of Nuclear Physics, RSPE, The Australian National University, Canberra, ACT 0200 (Australia); Zhdanov, V.S. [Nuclear Physics Institute, Almaty (Kazakhstan)

    2014-12-15

    Highlights: • The K, L{sub 1–3}, M{sub 1–3} electron binding energies in Kr in the Pt bulk determined. • The K, L{sub 1–3}, M{sub 1–3} electron binding energies in Kr in an evaporated Rb layer obtained. • The krypton K, L{sub 1–3}, M{sub 1} atomic level widths determined for the both host matrices. • The Kr KL{sub 2}L{sub 3}({sup 1}D{sub 2}) Auger transition energies measured for the both host matrices. • The KL{sub 2}L{sub 3}({sup 1}D{sub 2}) energy difference between Rb and Kr in the Pt host measured. • Dirac–Fock calculations of the Kr KLL Auger transitions performed. - Abstract: The low-energy electron spectra emitted in the radioactive decay of the {sup 83}Rb and {sup 83}Sr isotopes were measured with a combined electrostatic electron spectrometer. Radioactive sources used were prepared by ion implantation of {sup 83}Sr into a high purity polycrystalline platinum foil at 30 keV and by vacuum-evaporation deposition of {sup 83}Rb on the same type of foil. From the measured conversion electron spectra, the electron binding energies (referenced to the Fermi level) for the K, L{sub 1}, L{sub 2}, L{sub 3}, M{sub 1}, M{sub 2}, and M{sub 3} shell/subshells of krypton in the platinum host were determined to be 14316.4(12), 1914.3(9), 1720.3(9), 1667.6(9), 281.5(9), 209.6(13), and 201.2(15) eV, respectively, and those for the evaporated layer were observed to be lower by 0.7(1) eV. For both host matrices, values of 2.3(2), 4.6(2), 1.7(2), 1.3(2), and 3.2(3) eV were obtained for the krypton K, L{sub 1}, L{sub 2}, L{sub 3}, and M{sub 1} natural atomic level widths, respectively. The absolute energies of 10838.5(9) and 10839.5(10) eV were measured for the KL{sub 2}L{sub 3}({sup 1}D{sub 2}) Auger transition in krypton implanted in Pt and generated in the evaporated rubidium layer, respectively. A value of 601.0(8) eV was measured for the energy difference of the KL{sub 2}L{sub 3}({sup 1}D{sub 2}) transitions in Rb and Kr in the Pt host

  4. Correlation between energy deposition and molecular damage from Auger electrons: A case study of ultra-low energy (5-18 eV) electron interactions with DNA.

    Science.gov (United States)

    Rezaee, Mohammad; Hunting, Darel J; Sanche, Léon

    2014-07-01

    The present study introduces a new method to establish a direct correlation between biologically related physical parameters (i.e., stopping and damaging cross sections, respectively) for an Auger-electron emitting radionuclide decaying within a target molecule (e.g., DNA), so as to evaluate the efficacy of the radionuclide at the molecular level. These parameters can be applied to the dosimetry of Auger electrons and the quantification of their biological effects, which are the main criteria to assess the therapeutic efficacy of Auger-electron emitting radionuclides. Absorbed dose and stopping cross section for the Auger electrons of 5-18 eV emitted by(125)I within DNA were determined by developing a nanodosimetric model. The molecular damages induced by these Auger electrons were investigated by measuring damaging cross section, including that for the formation of DNA single- and double-strand breaks. Nanoscale films of pure plasmid DNA were prepared via the freeze-drying technique and subsequently irradiated with low-energy electrons at various fluences. The damaging cross sections were determined by employing a molecular survival model to the measured exposure-response curves for induction of DNA strand breaks. For a single decay of(125)I within DNA, the Auger electrons of 5-18 eV deposit the energies of 12.1 and 9.1 eV within a 4.2-nm(3) volume of a hydrated or dry DNA, which results in the absorbed doses of 270 and 210 kGy, respectively. DNA bases have a major contribution to the deposited energies. Ten-electronvolt and high linear energy transfer 100-eV electrons have a similar cross section for the formation of DNA double-strand break, while 100-eV electrons are twice as efficient as 10 eV in the induction of single-strand break. Ultra-low-energy electrons (electron emitting radionuclides; hence, they should be considered in the dosimetry calculation of such radionuclides. Moreover, absorbed dose is not an appropriate physical parameter for nanodosimetry

  5. Correlation between energy deposition and molecular damage from Auger electrons: A case study of ultra-low energy (5–18 eV) electron interactions with DNA

    Science.gov (United States)

    Rezaee, Mohammad; Hunting, Darel J.; Sanche, Léon

    2015-01-01

    Purpose The present study introduces a new method to establish a direct correlation between biologically related physical parameters (i.e., stopping and damaging cross sections, respectively) for an Auger-electron emitting radionuclide decaying within a target molecule (e.g., DNA), so as to evaluate the efficacy of the radionuclide at the molecular level. These parameters can be applied to the dosimetry of Auger electrons and the quantification of their biological effects, which are the main criteria to assess the therapeutic efficacy of Auger-electron emitting radionuclides. Methods Absorbed dose and stopping cross section for the Auger electrons of 5–18 eV emitted by 125I within DNA were determined by developing a nanodosimetric model. The molecular damages induced by these Auger electrons were investigated by measuring damaging cross section, including that for the formation of DNA single- and double-strand breaks. Nanoscale films of pure plasmid DNA were prepared via the freeze-drying technique and subsequently irradiated with low-energy electrons at various fluences. The damaging cross sections were determined by employing a molecular survival model to the measured exposure–response curves for induction of DNA strand breaks. Results For a single decay of 125I within DNA, the Auger electrons of 5–18 eV deposit the energies of 12.1 and 9.1 eV within a 4.2-nm3 volume of a hydrated or dry DNA, which results in the absorbed doses of 270 and 210 kGy, respectively. DNA bases have a major contribution to the deposited energies. Ten-electronvolt and high linear energy transfer 100-eV electrons have a similar cross section for the formation of DNA double-strand break, while 100-eV electrons are twice as efficient as 10 eV in the induction of single-strand break. Conclusions Ultra-low-energy electrons (electron emitting radionuclides; hence, they should be considered in the dosimetry calculation of such radionuclides. Moreover, absorbed dose is not an appropriate

  6. Surface studies of praseodymium by electron spectroscopies

    Energy Technology Data Exchange (ETDEWEB)

    Krawczyk, Mirosław, E-mail: mkrawczyk@ichf.edu.pl; Pisarek, Marcin; Lisowski, Wojciech; Jablonski, Aleksander

    2016-12-01

    Highlights: • Pr foil. • EPES applied to measure the IMFPs in Pr samples after 3 keV Ar{sup +} ion etching. • Etched surfaces found to be formed by oxygen-containing Pr. • Measured IMFPs for E = 0.5–2 keV were approximated by Eq. (2). • The IMFPs were slightly affected by oxygen and agreed well with those from Eq. (3). - Abstract: Electron transport properties in praseodymium (Pr) foil samples were studied by elastic-peak electron spectroscopy (EPES). Prior to EPES measurements, the Pr sample surface was pre-sputtered by Ar ions with ion energy of 2–3 keV. After such treatment, the Pr sample still contained about 10 at.% of residual oxygen in the surface region, as detected by X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES) analyses. The inelastic mean free path (IMFP), characterizing electron transport within this region (4 nm-thick), was evaluated from EPES using both Ni and Au standards as a function of energy in the range of 0.5–2 keV. Experimental IMFPs, λ, were approximated by the simple function λ = kE{sup p}, where E is energy (in eV), and k = 0.1549 and p = 0.7047 were the fitted parameters. These values were compared with IMFPs for the praseodymium surface in which the presence of oxygen was tentatively neglected, and also with IMFPs resulting from the TPP-2M predictive equation for bulk praseodymium. We found that the measured IMFP values to be only slightly affected by neglect of oxygen in calculations. The fitted function applied here was consistent with the energy dependence of the EPES-measured IMFPs. Additionally, the measured IMFPs were found to be from 2% to 4.2% larger than the predicted IMFPs for praseodymium in the energy range of 500–1000 eV. For electron energies of 1500 eV and 2000 eV, there was an inverse correlation between these values, and then the resulting deviations of −0.4% and −2.7%, respectively, were calculated.

  7. The change of the LMM auger spectra in 3d-metals due to oxidation and its correlation with the change of the atomic magnetic moment.

    Science.gov (United States)

    Zheltysheva, Olga R; Surnin, Dmitry V; Guy, Dmitry E; Gil'mutdinov, Faat Z; Ruts, Yuri V; Grebennikov, Vladimir I

    2005-12-01

    The surfaces of crystalline samples of 3d-metals (Mn, Fe, Co, Ni, and Cu) and their stoichiometric oxides have been studied by Auger spectroscopy. A correlation between the change in the LVV (L-inner level-valence-valence electron transition) Auger intensities and the change of the squares of the corresponding atomic-magnetic moments has been observed. This is because of the complicated nature of the Auger process. That is, the Auger electron emission is a result of the inner atomic level excitation by electron impact and Auger annihilation of the inner-level hole. Therefore, the Auger process has been considered a second-order process, and spin polarization of the valence states has been taken into account for the LMM (L-inner level-M-inner level-M-inner level electron transition) Auger spectra of 3d-metals.

  8. Evaluation of Cobalt-Labeled Octreotide Analogs for Molecular Imaging and Auger Electron-Based Radionuclide Therapy

    DEFF Research Database (Denmark)

    Thisgaard, Helge; Olsen, Birgitte Brinkmann; Dam, Johan Hygum

    2014-01-01

    The somatostatin receptor, which is overexpressed by many neuroendocrine tumors, is a well-known target for molecular imaging and peptide receptor radionuclide therapy. Recently, (57)Co-labeled DOTATOC, an octreotide analog, was shown to have the highest affinity yet found for somatostatin receptor...... subtype 2. The aim of this study was to evaluate the biologic effects of novel cobalt-labeled octreotide analogs targeting the somatostatin receptor to identify promising candidates for molecular imaging and Auger electron-based radionuclide therapy. METHODS: Cobalt-labeled DOTATATE, DOTATOC, and DOTANOC...... were prepared with (57)Co or (58m)Co for SPECT or Auger electron-based therapy, respectively. The cellular uptake and intracellular distribution of the radioligands were characterized with the pancreatic tumor cell line AR42J in vitro, including assessment of the therapeutic effects of (58m...

  9. Radioimmunotherapy of cancer with high linear energy transfer (LET) radiation delivered by radionuclides emitting α-particles or Auger electrons.

    Science.gov (United States)

    Aghevlian, Sadaf; Boyle, Amanda J; Reilly, Raymond M

    2017-01-15

    Radioimmunotherapy (RIT) aims to selectively deliver radionuclides emitting α-particles, β-particles or Auger electrons to tumors by conjugation to monoclonal antibodies (mAbs) that recognize tumor-associated antigens/receptors. The approach has been most successful for treatment of non-Hodgkin's B-cell lymphoma but challenges have been encountered in extending these promising results to the treatment of solid malignancies. These challenges include the low potency of β-particle emitters such as 131I, 177Lu or 90Y which have been commonly conjugated to the mAbs, due to their low linear energy transfer (LET=0.1-1.0keV/μm). Furthermore, since the β-particles have a 2-10mm range, there has been dose-limiting non-specific toxicity to hematopoietic stem cells in the bone marrow (BM) due to the cross-fire effect. Conjugation of mAbs to α-particle-emitters (e.g. 225Ac, 213Bi, 212Pb or 211At) or Auger electron-emitters (e.g. 111In, 67Ga, 123I or 125I) would increase the potency of RIT due to their high LET (50-230keV/μm and 4 to 26keV/μm, respectively). In addition, α-particles have a range in tissues of 28-100μm and Auger electrons are nanometer in range which greatly reduces or eliminates the cross-fire effect compared to β-particles, potentially reducing their non-specific toxicity to the BM. In this review, we describe the results of preclinical and clinical studies of RIT of cancer using radioimmunoconjugates emitting α-particles or Auger electrons, and discuss the potential of these high LET forms of radiation to improve the outcome of cancer patients. Copyright © 2015 Elsevier B.V. All rights reserved.

  10. Studies in ferromagnetism using electron polarization analysis Spectroscopy

    CERN Document Server

    Saubi, B H

    2001-01-01

    Motivated by recent reports of induced ferromagnetism in non-magnetic transition metals by rare earth metals, we have modified an existing Electron Spectroscopy with Polarization Analysis (ESPA) apparatus to allow for a set of experiments on induced ferromagnetism at Pd:Gd interfaces. We have investigated a number of magnetic materials for their potential as magnetically reversible substrates on which the Gd under layer could be grown. An evaporation source for Gd. suitable for use in Ultra High Vacuum (UHV) has been developed. Auger Electron Spectroscopy (AES) has been used to characterize the growth of Gd on a CO sub 6 sub 6 Si sub 1 sub 5 B sub 1 sub 4 Fe sub 4 Ni sub 1 ribbon substrate held at 100K, by comparing the peak to background (P/B) ratios of Gd and Co Auger lines as a function of overlayer film thickness. We have established that Gd grows in a kinetically limited statistical fashion. The magnetic behaviour of the Gd films on the Co-based ribbon substrate has been studied using Spin Polarized Seco...

  11. Electron Paramagnetic Resonance Spectroscopy

    Indian Academy of Sciences (India)

    IAS Admin

    Recently, electron paramagnetic resonance (EPR) spectros- copy has emerged as a powerful tool to study the structure and dynamics of biological macromolecules such as proteins, protein aggregates, RNA and DNA. It is used in combination with molecular modelling to study complex systems such as soluble proteins ...

  12. Post-collision interaction after inner-shell ionization by electron impact: the shape of Auger lines

    Energy Technology Data Exchange (ETDEWEB)

    Kuhn, W.; Feuerstein, B.; Mehlhorn, W. [Fakultaet fuer Physik, Universitaet Freiburg, Freiburg (Germany)

    2001-07-28

    We measured the lineshapes of Ne K-L{sub 2,3}L{sub 2,3} and Ar L{sub 2,3}-M{sub 2,3}M{sub 2,3} Auger electrons distorted by post-collision interaction (PCI) for electron-impact ionization. The excess energies E{sub 1}=E{sub 0}-I(nlj) (E{sub 0} and I(nlj) are the incident and the ionization energies) were 27-427 eV for Ne K ionization and 12-750 eV for Ar L{sub 3} ionization. For comparison we calculated theoretical Auger spectra where the PCI-distorted lineshape, obtained in eikonal theory (Sheinerman et al 1994 J. Phys. B: At. Mol. Opt. Phys. 27 5681), was convolved with the experimentally known spectrometer function and a Gaussian function for the Doppler effect of the thermally moving target atoms. The agreement of experimental and theoretical spectra is excellent in all cases. This demonstrates the quality of eikonal theory in calculating the PCI-distorted Auger lineshapes. (author)

  13. Post-collision interaction after inner-shell ionization by electron impact: the shape of Auger lines

    Science.gov (United States)

    Kuhn, W.; Feuerstein, B.; Mehlhorn, W.

    2001-07-01

    We measured the lineshapes of Ne K-L2,3L2,3 and Ar L2,3-M2,3M2,3 Auger electrons distorted by post-collision interaction (PCI) for electron-impact ionization. The excess energies E1 = E0-I(nlj) (E0 and I(nlj) are the incident and the ionization energies) were 27-427 eV for Ne K ionization and 12-750 eV for Ar L3 ionization. For comparison we calculated theoretical Auger spectra where the PCI-distorted lineshape, obtained in eikonal theory (Sheinerman et al 1994 J. Phys. B: At. Mol. Opt. Phys. 27 5681), was convolved with the experimentally known spectrometer function and a Gaussian function for the Doppler effect of the thermally moving target atoms. The agreement of experimental and theoretical spectra is excellent in all cases. This demonstrates the quality of eikonal theory in calculating the PCI-distorted Auger lineshapes.

  14. Prominent conjugate processes in the PCI recapture of photoelectrons revealed by high resolution Auger electron measurements of Xe

    Science.gov (United States)

    Azuma, Yoshiro; Kosugi, Satoshi; Suzuki, Norihiro; Shigemasa, Eiji; Iwayama, Hiroshi; Koike, Fumihiro

    2016-05-01

    The Xe (N5O2 , 3O2 , 3) Auger electron spectrum originating from 4d5/ 2 - 1 photoionization was measured with the photon energy tuned very close above the ionization threshold. As the photon energy approached the 4d5/ 2 - 1 photoionization threshold, Rydberg series structures including several angular momentum components were formed within the Auger profile by the recapture of the photoelectrons into high-lying final ion orbitals. Our spectrum with resolution much narrower than the lifetime width of the corresponding core excited state allowed us to resolve detailed structures due to the orbital angular momenta very clearly. Unexpectedly, conjugate peaks originating from the exchange of angular momentum between the photoelectron and the Auger electron through Post-Collision-Interaction were found to dominate the spectrum. The new assignments were in accord with the quantum defect values obtained for the high Rydberg series for singly charged ionic Xe + 5 p(1S0) ml. This work was supported by Japan Society for the Promotion of Science through Grants-in-Aid for Scientific Research No. 23600009.

  15. Electron spectroscopy of crystals

    CERN Document Server

    Nemoshkalenko, V V

    1979-01-01

    This book is conceived as a monograph, and represents an up-to-date collection of information concerning the use of the method of X-ray photoelectron spec­ troscopy in the study of the electron structure of crystals, as well as a personal interpretation of the subject by the authors. In a natural way, the book starts in Chapter 1 with a recapitulation of the fundamentals of the method, basic relations, principles of operation, and a com­ parative presentation of the characteristics and performances of the most com­ monly used ESCA instruments (from the classical ones-Varian, McPherson, Hewlett Packard, and IEEE-up to the latest model developed by Professor Siegbahn in Uppsala), and continues with a discussion of some of the difficult problems the experimentalist must face such as calibration of spectra, prepara­ tion of samples, and evaluation of the escape depth of electrons. The second chapter is devoted to the theory of photoemission from crystal­ line solids. A discussion of the methods of Hartree-Fo...

  16. iDEEAA: A novel, versatile apparatus for electron spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Lupulescu, C., E-mail: cosmin.lupulescu@helmholtz-berlin.de [Technische Universität Berlin, Institut für Optik und Atomare Physik, Straße des 17. Juni 135, 10623 Berlin (Germany); Arion, T. [Centre for Free-Electron Laser Science (DESY), Notkestrasse 85, 22607 Hamburg (Germany); Institut für Experimentalphysik, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg (Germany); Hergenhahn, U. [Max-Planck-Institut für Plasmaphysik, EURATOM Association, Teilinstitut Greifswald, Wendelsteinstr. 1, 17491 Greifswald (Germany); Ovsyannikov, R. [Helmholtz-Zentrum Berlin, Albert-Einstein-Str. 15, 12489 Berlin (Germany); Förstel, M. [Max-Planck-Institut für Plasmaphysik, EURATOM Association, Teilinstitut Greifswald, Wendelsteinstr. 1, 17491 Greifswald (Germany); Gavrila, G. [Technische Universität Chemnitz, Fakultät Elektrotechnik und Informationstechnik, Reichenhainer Str. 70, 09126 Chemnitz (Germany); Eberhardt, W. [Technische Universität Berlin, Institut für Optik und Atomare Physik, Straße des 17. Juni 135, 10623 Berlin (Germany); Centre for Free-Electron Laser Science (DESY), Notkestrasse 85, 22607 Hamburg (Germany)

    2013-12-15

    Highlights: •We developed an experimental end station for time- and angle-resolved X-ray electron spectroscopy. •The instrument can operate in combination with synchrotron radiation, VUV Helium discharge source or table-top high-harmonic laser sources. •Band mapping in solids is possible with unprecedented rapidity. •Electron–electron coincidence spectroscopy is performed at higher data collection rate (due to improved transmission) and with improved energy resolution. -- Abstract: We report the development and present status of the iDEEAA (Instrument for Direct Electron Energy and Angular Analysis) experimental end station for time- and angle-resolved X-ray photoelectron spectroscopy. The setup is based on multidimensional detection of photoelectrons by means of both time-of-flight (TOF) and/or electrostatic analyzers. The instrument offers the possibility to record simultaneously and independently photoelectron and Auger electron spectra. Samples can be either gases or solids. The system can operate with multiple photon sources, such as laboratory-based table-top laser extreme ultraviolet (EUV) sources, monochromatic Helium discharge lamp and soft X-ray synchrotron pulses. We demonstrate the performance of the setup by carrying out electron–electron coincidence experiments on CH{sub 4} and by mapping the band structure of Bi{sub 2}Se{sub 3} using photons of the BESSY II electron storage ring.

  17. sup>135sup>La as an auger-electron emitter for targeted internal radiotherapy

    DEFF Research Database (Denmark)

    Fonslet, Jesper; Lee, Boon Quan; Tran, Thuy A.

    2018-01-01

    proton irradiation of metallic natBa on a medical cyclotron, and was isolated and purified by trap-and-release on weak cation-exchange resin. The average production rate was 407 ± 19 MBq/µA (saturation activity, n = 3), and the radionuclidic purity was 98% at 20 h post irradiation. Chemical separation......Introduction: 135La has favorable nuclear and chemical properties for Auger-based targeted internal radiotherapy. Here we present detailed investigations of the production, emissions, imaging characteristics, and dosimetry related to 135La therapy. Methods and Results: 135La was produced by 16.5 MeV...... recovered > 98 % of the 135La with an effective molar activity of 70 ±20 GBq/µmol. To better assess cellular and organ dosimetry of this nuclide, we have recalculated the X-ray and Auger emission spectra using a Monte Carlo model accounting for effects of multiple vacancies during the Auger cascade...

  18. Development of DNA-based radiopharmaceuticals carrying Auger-electron emitters for anti-gene radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Panyutin, I.G.; Winters, T.A.; Feinendegen, L.E.; Neumann, R.D. [National Institutes of Health, Bethesda, MD (United States). Dept. of Nuclear Medicine

    2000-09-01

    Targeting of radiation damage to specific DNA sequences is the essence of antigen radiotherapy. This technique also provides a tool to study molecular mechanisms of DNA repair on a defined, single radio damaged site. It was achieved such sequence-specific radio damage by combining the highly localized DNA damage produced by the decay of Auger-electron-emitters such as {sup 125}I with the sequence-specific action of triplex-forming oligonucleotides (TFO). TFO complementary to polypurine-polypyrimidine regions of human genes were synthesized and labeled with {sup 125}I-dCTP by the primer extension method. {sup 125}I-TFO were delivered into cells with several delivery systems. In addition, human enzymes capable of supporting DNA single-strand-break repair were isolated and assessed for their role in the repair of this lesion. Also, the mutagenicity and repairability of {sup 125}I-TFO-induced double strand breaks (DSB) were assessed by repair of plasmid possessing a site-specific DSB lesion. Using plasmids containing target polypurine-polypyrimidine tracts, it was obtained the fine structure of sequence-specific DNA breaks produced by decay of {sup 125}I with single-nucleotide resolution. It was showed that the designed {sup 125}I-TFO in nanomolar concentrations could bind to and introduce double-strand breaks into the target sequences in situ, i.e., within isolated nuclei and intact digitonin-permeabilized cells. It was also showed {sup 125}I-TFO-induced DSB to be highly mutagenic lesions resulting in a mutation frequency of nearly 80%, with deletions comprising the majority of mutations. The results obtained demonstrate the ability of {sup 125}I-TFO to target specific sequences in their natural environment - within eukaryotic nucleus. Repair of {sup 125}I-TFO-induced DNA damage should typically result in mutagenic gene inactivation.

  19. 135La as an Auger-electron emitter for targeted internal radiotherapy

    Science.gov (United States)

    Fonslet, J.; Lee, B. Q.; Tran, T. A.; Siragusa, M.; Jensen, M.; Kibédi, T.; E Stuchbery, A.; Severin, G. W.

    2018-01-01

    135La has favorable nuclear and chemical properties for Auger-based targeted internal radiotherapy. Here we present detailed investigations of the production, emissions, and dosimetry related to 135La therapy. 135La was produced by 16.5 MeV proton irradiation of metallic natBa on a medical cyclotron, and was isolated and purified by trap-and-release on weak cation-exchange resin. The average production rate was 407  ±  19 MBq µA‑1 (saturation activity), and the radionuclidic purity was 98% at 20 h post irradiation. Chemical separation recovered  >  98 % of the 135La with an effective molar activity of 70  ±  20 GBq µmol‑1. To better assess cellular and organ dosimetry of this nuclide, we have calculated the x-ray and Auger emission spectra using a Monte Carlo model accounting for effects of multiple vacancies during the Auger cascade. The generated Auger spectrum was used to calculate cellular S-factors. 135La was produced with high specific activity, reactivity, radionuclidic purity, and yield. The emission spectrum and the dosimetry are favorable for internal radionuclide therapy.

  20. Rational evaluation of the therapeutic effect and dosimetry of auger electrons for radionuclide therapy in a cell culture model.

    Science.gov (United States)

    Shinohara, Ayaka; Hanaoka, Hirofumi; Sakashita, Tetsuya; Sato, Tatsuhiko; Yamaguchi, Aiko; Ishioka, Noriko S; Tsushima, Yoshito

    2017-12-13

    Radionuclide therapy with low-energy auger electron emitters may provide high antitumor efficacy while keeping the toxicity to normal organs low. Here we evaluated the usefulness of an auger electron emitter and compared it with that of a beta emitter for tumor treatment in in vitro models and conducted a dosimetry simulation using radioiodine-labeled metaiodobenzylguanidine (MIBG) as a model compound. We evaluated the cellular uptake of 125I-MIBG and the therapeutic effects of 125I- and 131I-MIBG in 2D and 3D PC-12 cell culture models. We used a Monte Carlo simulation code (PHITS) to calculate the absorbed radiation dose of 125I or 131I in computer simulation models for 2D and 3D cell cultures. In the dosimetry calculation for the 3D model, several distribution patterns of radionuclide were applied. A higher cumulative dose was observed in the 3D model due to the prolonged retention of MIBG compared to the 2D model. However, 125I-MIBG showed a greater therapeutic effect in the 2D model compared to the 3D model (respective EC50 values in the 2D and 3D models: 86.9 and 303.9 MBq/cell), whereas 131I-MIBG showed the opposite result (respective EC50 values in the 2D and 3D models: 49.4 and 30.2 MBq/cell). The therapeutic effect of 125I-MIBG was lower than that of 131I-MIBG in both models, but the radionuclide-derived difference was smaller in the 2D model. The dosimetry simulation with PHITS revealed the influence of the radiation quality, the crossfire effect, radionuclide distribution, and tumor shape on the absorbed dose. Application of the heterogeneous distribution series dramatically changed the radiation dose distribution of 125I-MIBG, and mitigated the difference between the estimated and measured therapeutic effects of 125I-MIBG. The therapeutic effect of 125I-MIBG was comparable to that of 131I-MIBG in the 2D model, but the efficacy was inferior to that of 131I-MIBG in the 3D model, since the crossfire effect is negligible and the homogeneous distribution

  1. Investigation of production routes for the 161Ho Auger-electron emitting radiolanthanide, a candidate for therapy

    OpenAIRE

    Tárkányi, F.; Ditrói, F.; Hermanne, A.; Takács, S.; Ignatyuk, A. V.

    2013-01-01

    The radiolanthanide 161Ho (2.48 h) is a promising Auger-electron emitter for internal radiotherapy that can be produced with particle accelerators. The excitation functions of the natDy(p,xn)161Ho and natDy(d,x)161Ho reactions were measured up to 40 and 50 MeV respectively by using the stacked foil activation method and gamma-ray spectrometry. The experimental data were compared with results of the TALYS code available in the TENDL 2011 library [1]. The main parameters of different production...

  2. Biodistribution of modular nanotransporter carrying Auger electron emitter and targeted at melanoma cells in murine tumor model

    Science.gov (United States)

    Vorontsova, M. S.; Morozova, N. B.; Karmakova, T. A.; Rosenkranz, A. A.; Slastnikova, T. A.; Petriev, V. M.; Smoryzanova, O. A.; Tischenko, V. K.; Yakubovskaya, R. I.; Kaprin, A. D.; Sobolev, A. S.

    2017-09-01

    Recombinant modular nanotransporter containing α-melanocyte-stimulating hormone peptide sequence (MNT-MSH) as a ligand module was designed for nucleus-targeted delivery of cytotoxic agents into melanoma cells. MNT-MSH radiolabeled with Auger electron emitter (111In-NOTA-MNT-MSH) showed a high antitumor efficacy in mice bearing syngeneic melanoma after intratumoral (i.t.) injection. This study is aimed at evaluating the biodistribution of the radioconjugate in melanoma tumor model in vivo. 111In-NOTA-MNT-MSH was administered i.t. in C57Bl/6j mice bearing subcutaneously implanted B16-F1 murine melanoma cells, expressing high levels of MCR1. The tissue uptake of radioactivity was determined ex vivo by γ-counter measurements. The intravenous route of administration did not provide a desirable level of radioactivity accumulation in the tumor, possibly, due to a high uptake of the transporter in liver tissue. After i.t. administration 111In-NOTA-MNT-MSH provided a high local retention of radionuclide, ranged from 400 to 350 %ID/g within at least 48 hours post-injection. MNT containing Auger electron emitter and α-MSH peptide as vector ligand could be a promising basis for radiopharmaceutical preparations intended for melanoma treatment.

  3. Alpha and conversion electron spectroscopy of 238,239Pu and 241Am and alpha-conversion electron coincidence measurements

    Energy Technology Data Exchange (ETDEWEB)

    Dion, Michael P.; Miller, Brian W.; Warren, Glen A.

    2016-09-01

    A technique to determine the isotopics of a mixed actinide sample has been proposed by measuring the coincidence of the alpha particle during radioactive decay with the conversion electron (or Auger) emitted during the relaxation of the daughter isotope. This presents a unique signature to allow the deconvolution of isotopes that possess overlapping alpha particle energy. The work presented here are results of conversion electron spectroscopy of 241Am, 238Pu and 239Pu using a dual-stage peltier-cooled 25 mm2 silicon drift detector. A passivated ion implanted planar silicon detector provided measurements of alpha spectroscopy. The conversion electron spectra were evaluated from 20–55 keV based on fits to the dominant conversion electron emissions, which allowed the relative conversion electron emission intensities to be determined. These measurements provide crucial singles spectral information to aid in the coincident measurement approach.

  4. Auger-electron spectra of F{sub 3}SiCH{sub 2}CH{sub 2}Si(CH{sub 3}){sub 3} obtained by using monochromatized synchrotron radiation

    Energy Technology Data Exchange (ETDEWEB)

    Nagaoka, Shin-ichi, E-mail: nagaoka@ehimegw.dpc.ehime-u.ac.j [Department of Chemistry, Faculty of Science, Ehime University, Matsuyama 790-8577 (Japan); Nitta, Akiko [Department of Chemistry, Faculty of Science, Ehime University, Matsuyama 790-8577 (Japan); Tamenori, Yusuke [Japan Synchrotron Radiation Research Institute/SPring-8, 1-1-1 Kouto, Sayo-cho, Sayo-gun 679-5198 (Japan); Fukuzawa, Hironobu; Ueda, Kiyoshi [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577 (Japan); Takahashi, Osamu [Department of Chemistry, Graduate School of Science, Hiroshima University, Higashi-Hiroshima 739-8526 (Japan); Kakiuchi, Takuhiro [Department of Chemistry, Faculty of Science, Ehime University, Matsuyama 790-8577 (Japan); Institute of Materials Structure Science (IMSS), High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba 305-0801 (Japan); Kitajima, Yoshinori; Mase, Kazuhiko; Suzuki, Isao H. [Institute of Materials Structure Science (IMSS), High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba 305-0801 (Japan)

    2009-12-15

    A study on Auger-electron spectra of F{sub 3}SiCH{sub 2}CH{sub 2}Si(CH{sub 3}){sub 3} was performed by using monochromatized synchrotron radiation. The normal Si:L{sub 23}VV Auger-electron spectrum was measured in the vapor phase and characterized through the ab initio molecular orbital calculation. The cascade Si:L{sub 23}VV Auger-electron spectra were also obtained by L{sub 23}-holes creation through Si:KL{sub 23}L{sub 23} Auger transitions after Si:1s photoexcitation in the vapor phase or its photoelectron emission in the condensed phase. Further the C:KVV and F:KVV Auger-electron spectra were measured and discussed in comparison with those of some related molecules.

  5. A perfect wetting of Mg monolayer on Ag(111) under atomic scale investigation: First principles calculations, scanning tunneling microscopy, and Auger spectroscopy

    Science.gov (United States)

    Migaou, Amani; Sarpi, Brice; Guiltat, Mathilde; Payen, Kevin; Daineche, Rachid; Landa, Georges; Vizzini, Sébastien; Hémeryck, Anne

    2016-05-01

    First principles calculations, scanning tunneling microscopy, and Auger spectroscopy experiments of the adsorption of Mg on Ag(111) substrate are conducted. This detailed study reveals that an atomic scale controlled deposition of a metallic Mg monolayer perfectly wets the silver substrate without any alloy formation at the interface at room temperature. A liquid-like behavior of the Mg species on the Ag substrate is highlighted as no dot formation is observed when coverage increases. Finally a layer-by-layer growth mode of Mg on Ag(111) can be predicted, thanks to density functional theory calculations as observed experimentally.

  6. Vibrational spectroscopy in the electron microscope.

    Science.gov (United States)

    Krivanek, Ondrej L; Lovejoy, Tracy C; Dellby, Niklas; Aoki, Toshihiro; Carpenter, R W; Rez, Peter; Soignard, Emmanuel; Zhu, Jiangtao; Batson, Philip E; Lagos, Maureen J; Egerton, Ray F; Crozier, Peter A

    2014-10-09

    Vibrational spectroscopies using infrared radiation, Raman scattering, neutrons, low-energy electrons and inelastic electron tunnelling are powerful techniques that can analyse bonding arrangements, identify chemical compounds and probe many other important properties of materials. The spatial resolution of these spectroscopies is typically one micrometre or more, although it can reach a few tens of nanometres or even a few ångströms when enhanced by the presence of a sharp metallic tip. If vibrational spectroscopy could be combined with the spatial resolution and flexibility of the transmission electron microscope, it would open up the study of vibrational modes in many different types of nanostructures. Unfortunately, the energy resolution of electron energy loss spectroscopy performed in the electron microscope has until now been too poor to allow such a combination. Recent developments that have improved the attainable energy resolution of electron energy loss spectroscopy in a scanning transmission electron microscope to around ten millielectronvolts now allow vibrational spectroscopy to be carried out in the electron microscope. Here we describe the innovations responsible for the progress, and present examples of applications in inorganic and organic materials, including the detection of hydrogen. We also demonstrate that the vibrational signal has both high- and low-spatial-resolution components, that the first component can be used to map vibrational features at nanometre-level resolution, and that the second component can be used for analysis carried out with the beam positioned just outside the sample--that is, for 'aloof' spectroscopy that largely avoids radiation damage.

  7. AMIGA at the Pierre Auger Observatory: The interface and control electronics of the first prototype muon counters

    Energy Technology Data Exchange (ETDEWEB)

    Videla, M., E-mail: mariela.videla@iteda.cnea.gov.ar [Instituto de Tecnologías en Detección de Astropartículas (CNEA, CONICET, UNSAM) Centro Atómico Constituyentes, Avda. Gral. Paz 1499 (1650) San Martin, Pcia. de Buenos Aires (Argentina); Platino, M., E-mail: manuel.platino@iteda.cnea.gov.ar [Instituto de Tecnologías en Detección de Astropartículas (CNEA, CONICET, UNSAM) Centro Atómico Constituyentes, Avda. Gral. Paz 1499 (1650) San Martin, Pcia. de Buenos Aires (Argentina); García, B. [Instituto de Tecnologías en Detección y Astropartículas, (CNEA, CONICET, UNSAM) Regional Cuyo, Azopardo 313 (5501) Godoy Cruz, Pcia. de Mendoza (Argentina); Universidad Tecnológica Nacional, Facultad Regional Mendoza Rodriguez 273, Ciudad Mendoza, CP (M5502AJE) (Argentina); Almela, A. [Instituto de Tecnologías en Detección de Astropartículas (CNEA, CONICET, UNSAM) Centro Atómico Constituyentes, Avda. Gral. Paz 1499 (1650) San Martin, Pcia. de Buenos Aires (Argentina); Vega, G. de la [Instituto de Tecnologías en Detección y Astropartículas, (CNEA, CONICET, UNSAM) Regional Cuyo, Azopardo 313 (5501) Godoy Cruz, Pcia. de Mendoza (Argentina); and others

    2015-08-11

    AMIGA is an enhancement of the Pierre Auger Observatory. The main goals of AMIGA are to extend the full efficiency range to lower energies of the Observatory and to measure the muon content of extensive air showers. Currently, it consists of 61 detector pairs, each one composed of a surface water-Cherenkov detector and a buried muon counter. Prototypes of the muon counter – buried at a depth of 2.25 m – were installed at each vertex of a hexagon and at its center with 750 m spacing. Each prototype has a detection area of 10 m{sup 2} segmented in 64 scintillation strips and coupled to a multi-anode PMT through optical fibers. The electronic systems of these prototypes are accessible via a service tube. An electronics interface and control board were designed to extract the data from the counter and to provide a remote control of the system. This article presents the design of the interface and control board and the results and performance during the first AMIGA acquisition period in 2012.

  8. Electron spectrometer for gas-phase spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Bozek, J.D.; Schlachter, A.S. [Ernest Orlando Lawrence Berkeley National Lab., CA (United States)

    1997-04-01

    An electron spectrometer for high-resolution spectroscopy of gaseous samples using synchrotron radiation has been designed and constructed. The spectrometer consists of a gas cell, cylindrical electrostatic lens, spherical-sector electron energy analyzer, position-sensitive detector and associated power supplies, electronics and vacuum pumps. Details of the spectrometer design are presented together with some representative spectra.

  9. Electron spectroscopy of rubber and resin-based composites containing 2D carbon

    Energy Technology Data Exchange (ETDEWEB)

    Kaciulis, S., E-mail: saulius.kaciulis@ismn.cnr.it [Institute for the Study of Nanostructured Materials, ISMN-CNR, P.O. Box 10, Monterotondo Stazione, 00015 Roma (Italy); Mezzi, A.; Balijepalli, S.K. [Institute for the Study of Nanostructured Materials, ISMN-CNR, P.O. Box 10, Monterotondo Stazione, 00015 Roma (Italy); Lavorgna, M. [Institute of Polymers, Composites and Biomaterials, IPCB-CNR, P.le Fermi, 80055 Napoli (Italy); Xia, H.S. [State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu, 610065 Sichuan (China)

    2015-04-30

    Composite materials with 2D carbon (graphene and/or single wall carbon nanotubes) are very promising due to their extraordinary electrical and mechanical properties. Graphene and natural rubber composites, which may be used for the gaskets or sealants, were prepared by ultrasonically assisted latex-mixing exfoliation and in-situ reduction process, with two vulcanization approaches: roll-mixing and hot-pressing. Also the resin-based composites, filled with micro-particles of Ag and graphene or carbon nanotubes, have been studied. The standards for the compositional characterization of these materials still are not established. In addition to the mostly used techniques, such as Raman spectroscopy and electron microscopy, also Auger electron spectroscopy can be employed for the identification of graphene. In this study, the shape of C KVV peak, excited by electron beam and X-ray photons, has been investigated in different composite materials containing graphene and carbon nanotubes. A spectroscopic method for 2D carbon recognition, based on the D{sub x} parameter which is determined from C KVV signal excited by X-ray photons, was proposed and verified. Even a small content of graphene in different types of composites was sufficient for this recognition due to the dominating presence of graphene on the surface of composites. - Highlights: • Chemical composition of the rubber composites was determined by XPS. • Auger spectrum of carbon was used for graphene identification in composites. • Small content of graphene was sufficient for its recognition from the D parameter.

  10. Calculations of absorbed fractions in small water spheres for low-energy monoenergetic electrons and the Auger-emitting radionuclides (123)Ι and (125)Ι.

    Science.gov (United States)

    Bousis, Christos; Emfietzoglou, Dimitris; Nikjoo, Hooshang

    2012-12-01

    To calculate the absorbed fraction (AF) of low energy electrons in small tissue-equivalent spherical volumes by Monte Carlo (MC) track structure simulation and assess the influence of phase (liquid water versus density-scaled water vapor) and of the continuous-slowing-down approximation (CSDA) used in semi-analytic calculations. An event-by-event MC code simulating the transport of electrons in both the vapor and liquid phase of water using appropriate electron-water interaction cross sections was used to quantify the energy deposition of low-energy electrons in spherical volumes. Semi-analytic calculations within the CSDA using a convolution integral of the Howell range-energy expressions are also presented for comparison. The AF for spherical volumes of radii from 10-1000 nm are presented for monoenergetic electrons over the energy range 100-10,000 eV and the two Auger-emitting radionuclides (125)I and (123)I. The MC calculated AF for the liquid phase are found to be smaller than those of the (density scaled) gas phase by up to 10-20% for the monoenergetic electrons and 10% for the two Auger-emitters. Differences between the liquid-phase MC results and the semi-analytic CSDA calculations are up to ∼ 55% for the monoenergetic electrons and up to ∼ 35% for the two Auger-emitters. Condensed-phase effects in the inelastic interaction of low-energy electrons with water have a noticeable but relatively small impact on the AF for the energy range and target sizes examined. Depending on the electron energies, the semi-analytic approach may lead to sizeable errors for target sizes with linear dimensions below 1 micron.

  11. In-trap conversion electron spectroscopy

    CERN Document Server

    Weissman, L; Äystö, J; Forstner, O; Reisinger, K; Rinta-Antila, S

    2002-01-01

    The Penning trap REXTRAP at ISOLDE was used to test the feasibility of in-trap conversion electron spectroscopy. The results of simulations, experiments with solid conversion electron sources as well as first on-line and tests with trapped radioactive ions are presented. In addition to obtaining high-resolution spectroscopic data, the detection of conversion electrons was found to be a useful tool for the diagnostics of the trap operation. The tests proved the feasibility of in-trap spectroscopy but also revealed some potential problems to be addressed in the future.

  12. Materials research by electron momentum spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Canney, S.A.; Fang, Z.; Guo, X.; McCarthy, I.E. [Flinders Univ. of South Australia, Adelaide, SA (Australia). Electronic Structure of Materials Centre; Kheifets, A.S.; Vos, M.; Weigold, E. [Australian National Univ., Canberra, ACT (Australia). Research School of Physical Sciences and Engineering, Atomic and Molecular Physcis Laboratories

    1998-06-01

    Electron momentum spectroscopy (EMS), also known as (e,2e) spectroscopy is a relatively new technique for the research of materials. It directly determines the electronic structure of materials using binary electron-electron collisions. The measured intensity is proportional to the energy-momentum density, i.e. the modulus square of the wave function in momentum space. This intensity is simply the probability of finding an electron in the material with a particular combination of binding-energy and momentum. In contrast to photoemission measurements, EMS is able to resolve real momentum (rather than crystal-momentum) and the measured intensity is easily related to the electronic structure itself. The measured and calculated momentum densities of graphite, aluminium and amorphous silicon films are presented. 7 refs., 3 figs.

  13. Transcriptomic Signatures of Auger Electron Radioimmunotherapy Using Nuclear Targeting 111In-Trastuzumab for Potential Combination Therapies

    Science.gov (United States)

    Li, Huizi Keiko; Morokoshi, Yukie; Daino, Kazuhiro; Furukawa, Takako; Kamada, Tadashi; Saga, Tsuneo

    2015-01-01

    Abstract 111In-labeled trastuzumab modified with nuclear localizing signal (NLS) peptides (111In-trastuzumab-NLS) efficiently delivers an Auger electron (AE) emitter 111In into the cell nucleus and is thus a promising radiopharmaceutical in AE radioimmunotherapy (AE-RIT) for targeted killing of HER2-positive cancer. However, further improvement of its therapeutic efficacy is required. In this study, the authors show a transcriptomic approach to identify potential targets for enhancing the cytotoxic effects of 111In-trastuzumab-NLS. They generated two types of 111In-trastuzumab-NLS harboring different numbers of NLS peptides, 111In-trastuzumab-NLS-S and -L. These radioimmunoconjugates (230 and 460 kBq) showed a significant higher cytotoxicity to SKBR3 human breast cancer cells overexpressing HER2 compared to 111In-trastuzumab. Microarray analysis revealed that NF-kB-related genes (38 genes) were significantly changed in transcription by 111In trastuzumab-NLS-L (230 kBq) treatment. Quantitative reverse transcription polymerase chain reaction confirmed the microarray data by showing transcriptional alternation of selected NF-κB target genes in cells treated with 111In-trastuzumab-NLS-L. Interestingly, bortezomib, a drug known as a NF-κB modulator, significantly enhanced the cytotoxicity of 111In-trastuzumab-NLS-L in SKBR3 cells. Taken together, the transcriptome data suggest the possibility that the modulation of NF-kB signaling activity is a molecular signature of 111In-trastuzumab-NLS and coadministration of bortezomib may be efficacious in enhancement of AE-RIT with 111In-trastuzumab-NLS. PMID:26447839

  14. Absorbed dose evaluation of Auger electron-emitting radionuclides: impact of input decay spectra on dose point kernels and S-values

    Science.gov (United States)

    Falzone, Nadia; Lee, Boon Q.; Fernández-Varea, José M.; Kartsonaki, Christiana; Stuchbery, Andrew E.; Kibédi, Tibor; Vallis, Katherine A.

    2017-03-01

    The aim of this study was to investigate the impact of decay data provided by the newly developed stochastic atomic relaxation model BrIccEmis on dose point kernels (DPKs - radial dose distribution around a unit point source) and S-values (absorbed dose per unit cumulated activity) of 14 Auger electron (AE) emitting radionuclides, namely 67Ga, 80mBr, 89Zr, 90Nb, 99mTc, 111In, 117mSn, 119Sb, 123I, 124I, 125I, 135La, 195mPt and 201Tl. Radiation spectra were based on the nuclear decay data from the medical internal radiation dose (MIRD) RADTABS program and the BrIccEmis code, assuming both an isolated-atom and condensed-phase approach. DPKs were simulated with the PENELOPE Monte Carlo (MC) code using event-by-event electron and photon transport. S-values for concentric spherical cells of various sizes were derived from these DPKs using appropriate geometric reduction factors. The number of Auger and Coster-Kronig (CK) electrons and x-ray photons released per nuclear decay (yield) from MIRD-RADTABS were consistently higher than those calculated using BrIccEmis. DPKs for the electron spectra from BrIccEmis were considerably different from MIRD-RADTABS in the first few hundred nanometres from a point source where most of the Auger electrons are stopped. S-values were, however, not significantly impacted as the differences in DPKs in the sub-micrometre dimension were quickly diminished in larger dimensions. Overestimation in the total AE energy output by MIRD-RADTABS leads to higher predicted energy deposition by AE emitting radionuclides, especially in the immediate vicinity of the decaying radionuclides. This should be taken into account when MIRD-RADTABS data are used to simulate biological damage at nanoscale dimensions.

  15. Auger-Limited Carrier Recombination and Relaxation in CdSe Colloidal Quantum Wells

    Energy Technology Data Exchange (ETDEWEB)

    Baghani, Erfan; O’Leary, Stephen K.; Fedin, Igor; Talapin, Dmitri V.; Pelton, Matthew

    2015-03-19

    Using time-resolved photoluminescence spectroscopy, we show that two-exciton Auger recombination dominates carrier recombination and cooling dynamics in CdSe nanoplatelets, or colloidal quantum wells. The electron-hole recombination rate depends only on the number of electron-hole pairs present in each nanoplatelet, and is consistent with a twoexciton recombination process over a wide range of exciton densities. The carrier relaxation rate within the conduction and valence bands also depends only on the number of electron-hole pairs present, apart from an initial rapid decay, and is consistent with the cooling rate being limited by reheating due to Auger recombination processes. These Auger-limited recombination and relaxation dynamics are qualitatively different from the carrier dynamics in either colloidal quantum dots or epitaxial quantum wells. TOC FIGURE:

  16. Theoretical and experimental study of the double ionization by electron impact involving the Auger effect: processes and exchanges interferences; Etude theorique et experimentale de la double ionisation par impact electronique incluant l'effet auger: interferences d'echanges et de processus

    Energy Technology Data Exchange (ETDEWEB)

    Catoire, F

    2006-09-15

    In this work, double ionisation mechanisms of argon by electron impact in which the Auger effect is included have been studied as a function of the incident electron energy. Five and six fold differential cross sections in angle and in energy have been measured and analysed in a coplanar geometry. The efficiency of the apparatus has been improved by the use of a new toroidal analyser. For the first time, the six fold differential cross section in which the Auger electron and the ejected electron with identical kinetic energies (205 eV) are involved, was measured at an incident energy of 956 eV in the case of argon. In the theoretical models developed during this work, the triple continuum is represented by a manifold of coulomb waves describing the interaction of all electrons with the residual ion. Exchange effects between electrons were also included in the models. Comparison between experimental and theoretical results allows to study the relative contribution of the Auger process and the direct double ionisation on the angular dependence five fold differential cross section. In particular, the Auger process contribution seems to become increasingly important as the incident energy is increased.

  17. Calculation of DNA strand breaks due to direct and indirect effects of Auger electrons from incorporated 123I and 125I radionuclides using the Geant4 computer code.

    Science.gov (United States)

    Raisali, Gholamreza; Mirzakhanian, Lalageh; Masoudi, Seyed Farhad; Semsarha, Farid

    2013-01-01

    In this work the number of DNA single-strand breaks (SSB) and double-strand breaks (DSB) due to direct and indirect effects of Auger electrons from incorporated (123)I and (125)I have been calculated by using the Geant4-DNA toolkit. We have performed and compared the calculations for several cases: (125)I versus (123)I, source positions and direct versus indirect breaks to study the capability of the Geant4-DNA in calculations of DNA damage yields. Two different simple geometries of a 41 base pair of B-DNA have been simulated. The location of (123)I has been considered to be in (123)IdUrd and three different locations for (125)I. The results showed that the simpler geometry is sufficient for direct break calculations while indirect damage yield is more sensitive to the helical shape of DNA. For (123)I Auger electrons, the average number of DSB due to the direct hits is almost twice the DSB due to the indirect hits. Furthermore, a comparison between the average number of SSB or DSB caused by Auger electrons of (125)I and (123)I in (125)IdUrd and (123)IdUrd shows that (125)I is 1.5 times more effective than (123)I per decay. The results are in reasonable agreement with previous experimental and theoretical results which shows the applicability of the Geant-DNA toolkit in nanodosimetry calculations which benefits from the open-source accessibility with the advantage that the DNA models used in this work enable us to save the computational time. Also, the results showed that the simpler geometry is suitable for direct break calculations, while for the indirect damage yield, the more precise model is preferred.

  18. Electron spectroscopy study of the oxidation of a Zr-Fe getter. Pt. 1; Core spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Bastianon, A.; Braicovich, L.; Michelis, B. de (Ist. di Fisica, Politecnico di Milano (Italy))

    1992-03-15

    The room temperature oxidation (up to 2500 L) of a Zr-Fe getter having Zr{sub 2}Fe as majority component (80% of the total volume) is studied with X-ray photoemission (h{nu}=1253.6 eV) and Auger spectroscopy. Core photoemission (Zr 3d, Fe 2p and O 1s) and ZrM{sub 45}N{sub 23}V Auger spectra have been measured for increasing oxygen exposure. The oxidation proceeds via an interface suboxide up to an oxide having about the same chemical shift as ZrO{sub 2} (4.3 eV). At saturation the reacted overlayer is about 6 monolayers thick. A small fraction of Fe is found in the reacted overlayer (concentration around 15% of the that of the substrate). (orig.).

  19. Adsorption of atomic and molecular oxygen on Si(100)2x1: coverage dependence of the Auger O KVV lineshape.

    NARCIS (Netherlands)

    Wormeester, Herbert; Borg, H.J.; Terpstra, D.; Terpstra, D.; Keim, Enrico G.; van Silfhout, Arend

    1991-01-01

    By means of Auger electron spectroscopy (AES) we have monitored the room temperature adsorption of O2 and N2O on the clean Si(0 0 1)2 × 1 surface. We have found, for the first time, a significant variation in the intensity ratio of the K L1 L1 and K L23 L23 O Auger lines in the submonolayer range.

  20. Resonant Auger decay driving intermolecular Coulombic decay in molecular dimers.

    Science.gov (United States)

    Trinter, F; Schöffler, M S; Kim, H-K; Sturm, F P; Cole, K; Neumann, N; Vredenborg, A; Williams, J; Bocharova, I; Guillemin, R; Simon, M; Belkacem, A; Landers, A L; Weber, Th; Schmidt-Böcking, H; Dörner, R; Jahnke, T

    2014-01-30

    In 1997, it was predicted that an electronically excited atom or molecule placed in a loosely bound chemical system (such as a hydrogen-bonded or van-der-Waals-bonded cluster) could efficiently decay by transferring its excess energy to a neighbouring species that would then emit a low-energy electron. This intermolecular Coulombic decay (ICD) process has since been shown to be a common phenomenon, raising questions about its role in DNA damage induced by ionizing radiation, in which low-energy electrons are known to play an important part. It was recently suggested that ICD can be triggered efficiently and site-selectively by resonantly core-exciting a target atom, which then transforms through Auger decay into an ionic species with sufficiently high excitation energy to permit ICD to occur. Here we show experimentally that resonant Auger decay can indeed trigger ICD in dimers of both molecular nitrogen and carbon monoxide. By using ion and electron momentum spectroscopy to measure simultaneously the charged species created in the resonant-Auger-driven ICD cascade, we find that ICD occurs in less time than the 20 femtoseconds it would take for individual molecules to undergo dissociation. Our experimental confirmation of this process and its efficiency may trigger renewed efforts to develop resonant X-ray excitation schemes for more localized and targeted cancer radiation therapy.

  1. Temperature dependence of photoluminescence spectra of bilayer two-dimensional electron gases in LaAlO3/SrTiO3 superlattices: coexistence of Auger recombination and single-carrier trapping

    Directory of Open Access Journals (Sweden)

    H. J. Harsan Ma

    2015-06-01

    Full Text Available We report emerging photoluminescence (PL of bilayer two-dimensional electron gases (2DEG in LaAlO3/SrTiO3 (LAO/STO systems. A strong blue PL emerges in bilayer-2DEGs in LAO/STO/LAO/STO which doesn’t show in LAO/STO. PL band in bilayer-2DEGs includes both nearly temperature independent Auger recombination and temperature dependent free electron trapping while it crossovers from Auger recombination to single carrier trapping in LAO/STO. The PL signal of free electron trapping appears at high temperatures and it is much stronger than Auger recombination in the conducting channel in bilayer 2DEGs. This observation shows that high mobility carriers dominate the carrier dynamics in bilayer-2DEGs in LAO/STO superlattices.

  2. Auger Physicists visit CMS

    CERN Multimedia

    Hoch, Michael

    2012-01-01

    Visit at CERN P5 CMS in the experimental cavern Alan Watson, Auger Spokesperson Emeritus, University of Leeds; Jim Cronin, Nobel Laureate, Auger Spokesperson Emeritus, University of Chicago; Jim Virdee, CMS Former Spokesperson, Imperial College; Jim Matthews, Auger Co-Spokesperson, Louisiana State University

  3. MsSpec-1.0: A multiple scattering package for electron spectroscopies in material science

    Science.gov (United States)

    Sébilleau, Didier; Natoli, Calogero; Gavaza, George M.; Zhao, Haifeng; Da Pieve, Fabiana; Hatada, Keisuke

    2011-12-01

    We present a multiple scattering package to calculate the cross-section of various spectroscopies namely photoelectron diffraction (PED), Auger electron diffraction (AED), X-ray absorption (XAS), low-energy electron diffraction (LEED) and Auger photoelectron coincidence spectroscopy (APECS). This package is composed of three main codes, computing respectively the cluster, the potential and the cross-section. In the latter case, in order to cover a range of energies as wide as possible, three different algorithms are provided to perform the multiple scattering calculation: full matrix inversion, series expansion or correlation expansion of the multiple scattering matrix. Numerous other small Fortran codes or bash/csh shell scripts are also provided to perform specific tasks. The cross-section code is built by the user from a library of subroutines using a makefile. Program summaryProgram title: MsSpec-1.0 Catalogue identifier: AEJT_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEJT_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 504 438 No. of bytes in distributed program, including test data, etc.: 14 448 180 Distribution format: tar.gz Programming language: Fortran 77 Computer: Any Operating system: Linux, MacOs RAM: Bytes Classification: 7.2 External routines: Lapack ( http://www.netlib.org/lapack/) Nature of problem: Calculation of the cross-section of various spectroscopies. Solution method: Multiple scattering. Running time: The test runs provided only take a few seconds to run.

  4. Photoelectron spectroscopy bulk and surface electronic structures

    CERN Document Server

    Suga, Shigemasa

    2014-01-01

    Photoelectron spectroscopy is now becoming more and more required to investigate electronic structures of various solid materials in the bulk, on surfaces as well as at buried interfaces. The energy resolution was much improved in the last decade down to 1 meV in the low photon energy region. Now this technique is available from a few eV up to 10 keV by use of lasers, electron cyclotron resonance lamps in addition to synchrotron radiation and X-ray tubes. High resolution angle resolved photoelectron spectroscopy (ARPES) is now widely applied to band mapping of materials. It attracts a wide attention from both fundamental science and material engineering. Studies of the dynamics of excited states are feasible by time of flight spectroscopy with fully utilizing the pulse structures of synchrotron radiation as well as lasers including the free electron lasers (FEL). Spin resolved studies also made dramatic progress by using higher efficiency spin detectors and two dimensional spin detectors. Polarization depend...

  5. Angular distributions of {sup 2}P{sub {minus}} and {sup 2}P{sub +} auger electrons arising from B{sup +} ions on He

    Energy Technology Data Exchange (ETDEWEB)

    Shafroth, S.M. [Univ. of North Carolina, Chapel Hill, NC (United States)

    1994-12-31

    Projectile Auger electrons arising from 66 keV/U and 136 keV/U B{sup +} ions incident on 10 mTorr differentially pumped He were studied. Specifically, {sup 2}P{sub {minus}} and {sup 2}P{sub +} Auger electron transitions to the {sup 1}S ground state were detected using a modified version of the Swenson movable-channel-plate electron spectrometer. Electron spectra were obtained at 10, 20, 30, 40, 50, 60 deg lab and were transformed to; the projectile frame, where the energies of the (1s2s2p){sup 2}P{sub {minus}} and (1s2s2p){sup 2}P{sub +} Auger electron transitions to the (1s{sup 2}){sup 1}S g.s. are 161 and 164 eV respectively. The {sup 2}P{sub {minus}} and {sup 2}P{sub +} states may arise from two step processes such as; 1s-2p excitation and 2s ionization or 1s ionization and 2s-2p excitation of ground state projectiles (1s{sup 2}2s{sup 2}){sup 1}S. {sup 2}P{sub {minus}} and {sup 2}P{sub +} states most probably arise from metastable (1s{sup 2}2s2p){sup 1}P, {sup 3}P ion beams via single ionization of a 1s electron. The angular distributions for the {sup 2}P{sub {minus}} and {sup 2}P{sub +} states are quite different. The P{sub +} states are more forward peaked than the P{sub {minus}} states, which are more isotropic. As the B{sup +} energy increases, the P{sub +} state becomes more isotropic. Deveney et al. show that for 1 MeV/U C{sup 3+} on He, the P{sub +}/P{sub {minus}} ratio at 10{degrees} lab is not statistical. This may be connected with the different behaviors in the angular distributions reported on here.

  6. Positron lifetime measurements and positron-annihilation induced auger electron spectroscpy using slow positron beams; Teisoku yodenshi bimu wo mochiita yodenshi jumyo sokutei oyobi yodenshi shometsu reiki oje denshi bunko

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, R. [Electrotechnical Lab., Tsukuba (Japan)

    1996-02-20

    Slow positron beam with less than several eV can be controlled freely such as accelerating, throttling the beam size, shortening the pulse or making pulse with short time width and so forth. These low positron beams are applied to various measurements like Doppler broadening measurement of annihilation {gamma} rays or lifetime measurement of positron, and secondary particle measurements using positron microscope, positron electron ray diffraction, flight time method and so forth. In particular, these recent years, high intensity slow positron beams were possible using accelerators like electron linac and its application is increasing. In this report, pulse shortening method for high intensity slow positron beam, and incidence energy variable positron lifetime measurement method using this slow pulsed beam and flight time type positron-annihilation-induced auger electron spectroscopy are outlined. In future, these measurements can be possible to carry out with high resolution and also with high counting rate if higher intensity monochromatic excellent positron beam than present one is produced. 31 refs., 5 figs.

  7. 111In-BnDTPA-F3: an Auger electron-emitting radiotherapeutic agent that targets nucleolin.

    Science.gov (United States)

    Cornelissen, Bart; Waller, Andrew; Target, Carol; Kersemans, Veerle; Smart, Sean; Vallis, Katherine A

    2012-02-20

    The F3 peptide (KDEPQRRSARLSAKPAPPKPEPKPKKAPAKK), a fragment of the human high mobility group protein 2, binds nucleolin. Nucleolin is expressed in the nuclei of normal cells but is also expressed on the membrane of some cancer cells. The goal was to investigate the use of 111In-labeled F3 peptide for Auger electron-targeted radiotherapy. F3 was labeled with fluorescein isothiocyanate (FITC) for confocal microscopy and conjugated to p-SCN-benzyl-diethylenetriaminepentaacetic acid (BnDTPA) for labeling with 111In to form 111In-BnDTPA-F3. MDA-MB-231-H2N (231-H2N) human breast cancer cells were exposed to 111In-BnDTPA-F3 and used in cell fractionation, γH2AX immunostaining (a marker of DNA double-strand breaks), and clonogenic assays. In vivo, biodistribution studies of 111In-BnDTPA-F3 were performed in 231-H2N xenograft-bearing mice. In tumor growth delay studies, 111In-BnDTPA-F3 (3 μg, 6 MBq/μg) was administered intravenously to 231-H2N xenograft-bearing mice once weekly for 3 weeks. Membrane-binding of FITC-F3 was observed in 231-H2N cells, and there was co-localization of FITC-F3 with nucleolin in the nuclei. After exposure of 231-H2N cells to 111In-BnDTPA-F3 for 2 h, 1.7% of 111In added to the medium was membrane-bound. Of the bound 111In, 15% was internalized, and of this, 37% was localized in the nucleus. Exposure of 231-H2N cells to 111In-BnDTPA-F3 (1 μM, 6 MBq/μg) resulted in a dose-dependent increase in γH2AX foci and in a significant reduction of clonogenic survival compared to untreated cells or cells exposed to unlabeled BnDTPA-F3 (46 ± 4.1%, 100 ± 1.8%, and 132 ± 7.7%, respectively). In vivo, tumor uptake of 111In-BnDTPA-F3 (3 μg, 6 MBq/μg) at 3-h post-injection was 1% of the injected dose per gram (%ID/g), and muscle uptake was 0.5%ID/g. In tumor growth delay studies, tumor growth rate was reduced 19-fold compared to untreated or unlabeled BnDTPA-F3-treated mice (p = 0.023). 111In-BnDTPA-F3 is internalized into 231-H2N cells and translocates

  8. Simulation of Auger electron emission from nanometer-size gold targets using the Geant4 Monte Carlo simulation toolkit

    Energy Technology Data Exchange (ETDEWEB)

    Incerti, S., E-mail: sebastien.incerti@tdt.edu.vn [Division of Nuclear Physics, Ton Duc Thang University, Tan Phong Ward, District 7, Ho Chi Minh City (Viet Nam); Faculty of Applied Sciences, Ton Duc Thang University, Tan Phong Ward, District 7, Ho Chi Minh City (Viet Nam); Univ. Bordeaux, CENBG, UMR 5797, F-33170 Gradignan (France); CNRS, IN2P3, CENBG, UMR 5797, F-33170 Gradignan (France); Suerfu, B.; Xu, J. [Department of Physics, Princeton University, Princeton, NJ (United States); Ivantchenko, V. [Ecoanalytica, Moscow (Russian Federation); Geant4 Associates International Ltd, Hebden Bridge (United Kingdom); Mantero, A. [SWHARD srl, via Greto di Cornigliano 6r, 16152 Genova (Italy); Brown, J.M.C. [School of Mathematics and Physics, Queen’s University Belfast, Belfast, Northern Ireland (United Kingdom); Bernal, M.A. [Instituto de Física Gleb Wataghin, Universidade Estadual de Campinas, SP (Brazil); Francis, Z. [Université Saint Joseph, Faculty of Sciences, Department of Physics, Beirut (Lebanon); Karamitros, M. [Notre Dame Radiation Laboratory, University of Notre Dame, Notre Dame, IN (United States); Tran, H.N. [Division of Nuclear Physics, Ton Duc Thang University, Tan Phong Ward, District 7, Ho Chi Minh City (Viet Nam); Faculty of Applied Sciences, Ton Duc Thang University, Tan Phong Ward, District 7, Ho Chi Minh City (Viet Nam)

    2016-04-01

    A revised atomic deexcitation framework for the Geant4 general purpose Monte Carlo toolkit capable of simulating full Auger deexcitation cascades was implemented in June 2015 release (version 10.2 Beta). An overview of this refined framework and testing of its capabilities is presented for the irradiation of gold nanoparticles (NP) with keV photon and MeV proton beams. The resultant energy spectra of secondary particles created within and that escape the NP are analyzed and discussed. It is anticipated that this new functionality will improve and increase the use of Geant4 in the medical physics, radiobiology, nanomedicine research and other low energy physics fields.

  9. Contribution of Auger/conversion electrons to renal side effects after radionuclide therapy: preclinical comparison of (161)Tb-folate and (177)Lu-folate.

    Science.gov (United States)

    Haller, Stephanie; Pellegrini, Giovanni; Vermeulen, Christiaan; van der Meulen, Nicholas P; Köster, Ulli; Bernhardt, Peter; Schibli, Roger; Müller, Cristina

    2016-12-01

    The radiolanthanide (161)Tb has, in recent years, attracted increasing interest due to its favorable characteristics for medical application. (161)Tb exhibits similar properties to the widely-used therapeutic radionuclide (177)Lu. In contrast to (177)Lu, (161)Tb yields a significant number of short-ranging Auger/conversion electrons (≤50 keV) during its decay process. (161)Tb has been shown to be more effective for tumor therapy than (177)Lu if applied using the same activity. The purpose of this study was to investigate long-term damage to the kidneys after application of (161)Tb-folate and compare it to the renal effects caused by (177)Lu-folate. Renal side effects were investigated in nude mice after the application of different activities of (161)Tb-folate (10, 20, and 30 MBq per mouse) over a period of 8 months. Renal function was monitored by the determination of (99m)Tc-DMSA uptake in the kidneys and by measuring blood urea nitrogen and creatinine levels in the plasma. Histopathological analysis was performed by scoring of the tissue damage observed in HE-stained kidney sections from euthanized mice. Due to the co-emitted Auger/conversion electrons, the mean absorbed renal dose of (161)Tb-folate (3.0 Gy/MBq) was about 24 % higher than that of (177)Lu-folate (2.3 Gy/MBq). After application of (161)Tb-folate, kidney function was reduced in a dose- and time-dependent manner, as indicated by the decreased renal uptake of (99m)Tc-DMSA and the increased levels of blood urea nitrogen and creatinine. Similar results were obtained when (177)Lu-folate was applied at the same activity. Histopathological investigations confirmed comparable renal cortical damage after application of the same activities of (161)Tb-folate and (177)Lu-folate. This was characterized by collapsed tubules and enlarged glomeruli with fibrin deposition in moderately injured kidneys and glomerulosclerosis in severely damaged kidneys. Tb-folate induced dose-dependent radionephropathy over

  10. WE-AB-204-12: Dosimetry at the Sub-Cellular Scale of Auger-Electron Emitter 99m-Tc in a Mouse Single Thyroid Follicle Model

    Energy Technology Data Exchange (ETDEWEB)

    Taborda, A; Benabdallah, N; Desbree, A [Institut de Radioprotection et de Surete Nucleaire, Fontenay-aux-roses (France)

    2015-06-15

    Purpose: To perform a dosimetry study at the sub-cellular scale of Auger-electron emitter 99m-Tc using a mouse single thyroid cellular model to investigate the contribution of the 99m-Tc Auger-electrons to the absorbed dose and possible link to the thyroid stunning in in vivo experiments in mice, recently reported in literature. Methods: The simulation of S-values for Auger-electron emitting radionuclides was performed using both the recent MCNP6 software and the Geant4-DNA extension of the Geant4 toolkit. The dosimetric calculations were validated through comparison with results from literature, using a simple model of a single cell consisting of two concentric spheres of unit density water and for six Auger-electron emitting radionuclides. Furthermore, the S-values were calculated using a single thyroid follicle model for uniformly distributed 123-I and 125-I radionuclides and compared with published S-values. After validation, the simulation of the S-values was performed for the 99m-Tc radionuclide within the several mouse thyroid follicle cellular compartments, considering the radiative and non-radiative transitions of the 99m-Tc radiation spectrum. Results: The calculated S-values using MCNP6 are in good agreement with the results from literature, validating its use for the 99m-Tc S-values calculations. The most significant absorbed dose corresponds to the case where the radionuclide is uniformly distributed in the follicular cell’s nucleus, with a S-value of 7.8 mGy/disintegration, due mainly to the absorbed Auger-electrons. The results show that, at a sub-cellular scale, the emitted X-rays and gamma particles do not contribute significantly to the absorbed dose. Conclusion: In this work, MCNP6 was validated for dosimetric studies at the sub-cellular scale. It was shown that the contribution of the Auger-electrons to the absorbed dose is important at this scale compared to the emitted photons’ contribution and can’t be neglected. The obtained S

  11. Four-dimensional coherent electronic Raman spectroscopy

    Science.gov (United States)

    Harel, Elad

    2017-04-01

    The correlations between different quantum-mechanical degrees of freedom of molecular species dictate their chemical and physical properties. Generally, these correlations are reflected in the optical response of the system but in low-order or low-dimensionality measurement the signals are highly averaged. Here, we describe a novel four-dimensional coherent spectroscopic method that directly correlates within and between the manifold of electronic and vibrational states. The optical response theory is developed in terms of both resonant and non-resonant field-matter interactions. Using resonance to select coherences on specific electronic states creates opportunities to directly distinguish coherent dynamics on the ground and electronically excited potentials. Critically, this method is free from lower-order signals that have plagued other electronically non-resonant vibrational spectroscopies. The theory presented here compliments recent work on the experimental demonstration of the 4D spectroscopic method described. We highlight specific means by which non-trivial effects such as anharmonicity (diagonal and off-diagonal), mode-specific vibronic coupling, and curvature of the excited states manifest in different projections of the 4D spectrum.

  12. A database for the parameters of Auger differential spectra

    Energy Technology Data Exchange (ETDEWEB)

    Godowski, P.J. [Institute of Experimental Physics, University of Wroclaw, Wroclaw (Poland)

    1998-12-31

    The organization and structure of elaborated database of differential Auger spectra is presented. The first page of this set, available in complete form from the author, is demonstrated. The advantages page of taking into account the data set, in analytical work using Auger spectroscopy, are indicated. (author) 17 refs, 1 tab

  13. Hot Electron Nanoscopy and Spectroscopy (HENs)

    KAUST Repository

    Giugni, Andrea

    2017-08-17

    This chapter includes a brief description of different laser coupling methods with guided surface plasmon polariton (SPP) modes at the surface of a cone. It shows some devices, their electromagnetic simulations, and their optical characterization. A theoretical section illustrates the optical and quantum description of the hot charge generation rate as obtained for the SPP propagation along the nanocone in adiabatic compression. The chapter also shows some experimental results concerning the application of the hot electron nanoscopy and spectroscopy (HENs) in the so-called Schottky configuration, highlighting the sensitivity and the nanoscale resolution of the technique. The comparison with Kelvin probe and other electric atomic force microscopy (AFM) techniques points out the intrinsic advantages of the HENs. In the end, some further insights are given about the possibility of exploiting HENs with a pulsed laser at the femtosecond time scale without significant pulse broadening and dispersion.

  14. 3D Auger quantitative depth profiling of individual nanoscaled III–V heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Hourani, W. [Univ. Grenoble Alpes, F-38000 Grenoble (France); CEA, LETI, MINATEC Campus, F-38054 Grenoble (France); Gorbenko, V. [Univ. Grenoble Alpes, F-38000 Grenoble (France); CEA, LETI, MINATEC Campus, F-38054 Grenoble (France); Univ. Grenoble Alpes, LTM, CNRS, F-38000 Grenoble (France); Barnes, J.-P.; Guedj, C. [Univ. Grenoble Alpes, F-38000 Grenoble (France); CEA, LETI, MINATEC Campus, F-38054 Grenoble (France); Cipro, R.; Moeyaert, J.; David, S.; Bassani, F.; Baron, T. [Univ. Grenoble Alpes, LTM, CNRS, F-38000 Grenoble (France); Martinez, E., E-mail: eugenie.martinez@cea.fr [Univ. Grenoble Alpes, F-38000 Grenoble (France); CEA, LETI, MINATEC Campus, F-38054 Grenoble (France)

    2016-11-15

    Highlights: • The nanoscale chemical characterization of III–V heterostructures is performed using Auger depth profiling below decananometric spatial resolution. • Reliable indium quantification is achieved on planar structures for thicknesses down to 9 nm. • Quantitative 3D compositional depth profiles are obtained on patterned structures, with sufficient lateral resolution to analyze one single trench. • The Auger intrinsic spatial resolution is estimated around 150–200 nm using a comparison with HAADF-STEM. • Auger and SIMS provide reliable in-depth chemical analysis of such complex 3D heterostructures, in particular regarding indium quantification. - Abstract: The nanoscale chemical characterization of III–V heterostructures is performed using Auger depth profiling below decananometric spatial resolution. This technique is successfully applied to quantify the elemental composition of planar and patterned III–V heterostructures containing InGaAs quantum wells. Reliable indium quantification is achieved on planar structures for thicknesses down to 9 nm. Quantitative 3D compositional depth profiles are obtained on patterned structures, for trench widths down to 200 nm. The elemental distributions obtained in averaged and pointed mode are compared. For this last case, we show that Zalar rotation during sputtering is crucial for a reliable indium quantification. Results are confirmed by comparisons with secondary ion mass spectrometry, photoluminescence spectroscopy, transmission electron microscopy and electron dispersive X-ray spectroscopy. The Auger intrinsic spatial resolution is quantitatively measured using an original methodology based on the comparison with high angle annular dark field scanning transmission electron microscopy measurements at the nanometric scale.

  15. Observing Femtosecond Fragmentation Using Ultrafast X-ray-Induced Auger Spectra

    Directory of Open Access Journals (Sweden)

    Thomas J. A. Wolf

    2017-07-01

    Full Text Available Molecules often fragment after photoionization in the gas phase. Usually, this process can only be investigated spectroscopically as long as there exists electron correlation between the photofragments. Important parameters, like their kinetic energy after separation, cannot be investigated. We are reporting on a femtosecond time-resolved Auger electron spectroscopy study concerning the photofragmentation dynamics of thymine. We observe the appearance of clearly distinguishable signatures from thymine′s neutral photofragment isocyanic acid. Furthermore, we observe a time-dependent shift of its spectrum, which we can attribute to the influence of the charged fragment on the Auger electron. This allows us to map our time-dependent dataset onto the fragmentation coordinate. The time dependence of the shift supports efficient transformation of the excess energy gained from photoionization into kinetic energy of the fragments. Our method is broadly applicable to the investigation of photofragmentation processes.

  16. Electronic resonances in broadband stimulated Raman spectroscopy

    Science.gov (United States)

    Batignani, G.; Pontecorvo, E.; Giovannetti, G.; Ferrante, C.; Fumero, G.; Scopigno, T.

    2016-01-01

    Spontaneous Raman spectroscopy is a formidable tool to probe molecular vibrations. Under electronic resonance conditions, the cross section can be selectively enhanced enabling structural sensitivity to specific chromophores and reaction centers. The addition of an ultrashort, broadband femtosecond pulse to the excitation field allows for coherent stimulation of diverse molecular vibrations. Within such a scheme, vibrational spectra are engraved onto a highly directional field, and can be heterodyne detected overwhelming fluorescence and other incoherent signals. At variance with spontaneous resonance Raman, however, interpreting the spectral information is not straightforward, due to the manifold of field interactions concurring to the third order nonlinear response. Taking as an example vibrational spectra of heme proteins excited in the Soret band, we introduce a general approach to extract the stimulated Raman excitation profiles from complex spectral lineshapes. Specifically, by a quantum treatment of the matter through density matrix description of the third order nonlinear polarization, we identify the contributions which generate the Raman bands, by taking into account for the cross section of each process.

  17. Electron spectroscopies and inelastic processes in nanoclusters and solids: Theory and experiment

    Energy Technology Data Exchange (ETDEWEB)

    Taioli, Simone, E-mail: taioli@fbk.e [Interdisciplinary Laboratory for Computational Science (LISC), FBK-CMM and University of Trento, via Sommarive 18, I-38123 Trento (Italy); Department of Physics, University of Trento, Via Sommarive 14, I-38100, Trento (Italy); Simonucci, Stefano [Department of Physics, University of Camerino, via Madonna delle Carceri 9, 62032 Camerino (Italy); Interdisciplinary Laboratory for Computational Science (LISC), FBK-CMM and University of Trento, via Sommarive 18, I-38123 Trento (Italy); Calliari, Lucia [Interdisciplinary Laboratory for Computational Science (LISC), FBK-CMM and University of Trento, via Sommarive 18, I-38123 Trento (Italy); Dapor, Maurizio [Interdisciplinary Laboratory for Computational Science (LISC), FBK-CMM and University of Trento, via Sommarive 18, I-38123 Trento (Italy); Department of Materials Engineering and Industrial Technologies, University of Trento, via Mesiano 77, I-38123 Trento (Italy)

    2010-08-15

    The recent, very significant developments in high intensity and brightness electron and photon sources have opened new possibilities of applying electron spectroscopies, such as photoemission, Auger and electron energy loss, to the study of many interesting features in the dynamics of atoms, molecules and condensed-matter systems. In the last few years it has become possible to obtain electron spectra with an overall energy resolution (electron/photon source and electron spectrometer) considerably smaller than the linewidth of the investigated level and to study quantitatively the combined effects of the intrinsic dynamical properties of the system, of features of the incident beam and of the electron spectrometer on the spectral lineshape. For all these reasons, it is important to have theoretical methods that are able to analyze the dynamics of systems at any level of aggregation under the influence of an incident radiation and, simultaneously, to predict spectral lineshapes quantitatively by correlating their features with internal dynamics of the perturbed system. In this report, we present experiments and a critical overview of theoretical methods for interpreting electron spectra of atoms, molecules and solid-state systems. The general theoretical framework for this analysis is resonant multichannel scattering theory. Electron spectroscopies are, in fact, based on scattering processes in which the initial state consists of a projectile, typically photons or electrons, exciting a target to a resonant state, which has long lifetimes if compared to the collision time. This metastable state is embedded in the continuum of final states characterized by the presence of a few fragments, whose observation provides useful information on the properties of the system under study. Even if the general theory of scattering and decay phenomena has been largely developed, its specific application to electron spectroscopies in condensed matter and, in several cases also to

  18. Coherent pump pulses in Double Electron Electron Resonance Spectroscopy

    Science.gov (United States)

    Tait, Claudia E.; Stoll, Stefan

    2016-01-01

    The recent introduction of shaped pulses to Double Electron Electron Resonance (DEER) spectroscopy has led to significant enhancements in sensitivity through increased excitation bandwidths and improved control over spin dynamics. The application of DEER has so far relied on the presence of an incoherent pump channel to average out most undesired coherent effects of the pump pulse(s) on the observer spins. However, in fully coherent EPR spectrometers that are increasingly used to generate shaped pulses, the presence of coherent pump pulses means that these effects need to be explicitly considered. In this paper, we examine the effects of coherent rectangular and sech/tanh pump pulses in DEER experiments with up to three pump pulses. We show that, even in the absence of significant overlap of the observer and pump pulse excitation bandwidths, coherence transfer pathways involving both types of pulses generate spin echoes of considerable intensity. These echoes introduce artefacts, which, if not identified and removed, can easily lead to misinterpretation. We demonstrate that the observed echoes can be quantitatively modelled using a simple spin quantum dynamics approach that includes instrumental transfer functions. Based on an analysis of the echo crossing artefacts, we propose efficient phase cycling schemes for their suppression. This enables the use of advanced DEER experiments, characterized by high sensitivity and increased accuracy for long-distance measurements, on novel fully coherent EPR spectrometers. PMID:27339858

  19. Two-Dimensional Electronic Spectroscopy Using Incoherent Light: Theoretical Analysis

    CERN Document Server

    Turner, Daniel B; Sutor, Erika J; Hendrickson, Rebecca A; Gealy, M W; Ulness, Darin J

    2012-01-01

    Electronic energy transfer in photosynthesis occurs over a range of time scales and under a variety of intermolecular coupling conditions. Recent work has shown that electronic coupling between chromophores can lead to coherent oscillations in two-dimensional electronic spectroscopy measurements of pigment-protein complexes measured with femtosecond laser pulses. A persistent issue in the field is to reconcile the results of measurements performed using femtosecond laser pulses with physiological illumination conditions. Noisy-light spectroscopy can begin to address this question. In this work we present the theoretical analysis of incoherent two-dimensional electronic spectroscopy, I(4) 2D ES. Simulations reveal diagonal peaks, cross peaks, and coherent oscillations similar to those observed in femtosecond two-dimensional electronic spectroscopy experiments. The results also expose fundamental differences between the femtosecond-pulse and noisy-light techniques; the differences lead to new challenges and opp...

  20. Secondary-electron cascade in attosecond photoelectron spectroscopy from metals

    DEFF Research Database (Denmark)

    Baggesen, Jan Conrad; Madsen, Lars Bojer

    2009-01-01

    Attosecond spectroscopy is currently restricted to photon energies around 100 eV. We show that under these conditions, electron-electron scatterings, as the photoelectrons leave the metal, give rise to a tail of secondary electrons with lower energies and hence a significant background. We develop...

  1. Impedance Spectroscopy of Dielectrics and Electronic Conductors

    DEFF Research Database (Denmark)

    Bonanos, Nikolaos; Pissis, Polycarpos; Macdonald, J. Ross

    2013-01-01

    Impedance spectroscopy is used for the characterization of materials, such as electroceramics, solid and liquid electrochemical cells, dielectrics and also fully integrated devices, such as fuel cells. It consists of measuring the electrical impedance - or a closely related property, such as admi......Impedance spectroscopy is used for the characterization of materials, such as electroceramics, solid and liquid electrochemical cells, dielectrics and also fully integrated devices, such as fuel cells. It consists of measuring the electrical impedance - or a closely related property...

  2. Tungsten spectroscopy at the Livermore electron beam ion trap facility

    National Research Council Canada - National Science Library

    Clementson, J; Beiersdorfer, P; Brown, G.V; Gu, M.F; Lundberg, H; Podpaly, Y; Trabert, E

    2011-01-01

    .... In this paper, an overview of recent results from the Livermore WOLFRAM spectroscopy project is presented, which includes experimental investigations at the EBIT-I and SuperEBIT electron beam ion traps...

  3. Experimental system of ejected electron spectroscopy with ECR ion source

    Energy Technology Data Exchange (ETDEWEB)

    Kitazawa, Sin-iti [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1995-09-01

    The experiment of analyzing energy spectrum of electrons ejected from multiple electron capture process on ion-atom collision is carried out using ECR (Electron Cyclotron Resonance) ion source. An old collision system using gas atoms as target and a new system using vapour atoms are developed. In this report, the developments and exploitations of the experimental systems for the ejected electron spectroscopy with ECR Ion source are presented. (author).

  4. Bromine-80m-labeled estrogens: Auger-electron emitting, estrogen receptor-directed ligands with potential for therapy of estrogen receptor positive cancers

    Energy Technology Data Exchange (ETDEWEB)

    DeSombre, E.R.; Mease, R.C.; Hughes, A.; Harper, P.V.; DeJesus, O.T.; Friedman, A.M.

    1988-01-01

    A triphenylbromoethylene, 1,1-bis(p-hydroxyphenyl)-2-bromo-2-phenylethylene, Br-BHPE, and a bromosteroidal estrogen, 17..cap alpha..- bromovinylestradiol, BrVE/sub 2/, were labeled with the Auger electron emitting nuclide bromine-80m, prepared by the (p,n) reaction with /sup 80/Se. To assess their potential as estrogen receptor (ER) directed therapeutic substrates the bromine-80m labeled estrogens were injected into immature female rats and the tissue distribution studied at 0.5 and 2 hours. Both radiobromoestrogens showed substantial diethylstilbesterol (DES)-inhibitable localization in the ER rich tissues, uterus, pituitary, ovary and vagina at both time points. While the percent dose per gram tissue was higher for the Br-BHPE, the BrVE/sub 2/ showed higher tissue to blood ratios, especially at 2 hr, reflecting the lower blood concentrations of radiobromine following administration of the steroidal bromoestrogen. Comparing intraperitoneal, intravenous and subcutaneous routes of administration for the radiobromine labeled Br-BHPE, the intraperitoneal route was particularly advantageous to provide maximum, DES-inhibitable concentrations in the peritoneal, ER-rich target organs, the uterus, ovary and vagina. While uterine concentrations after BrBHPE were from 10--48% dose/g and after BrVE/sub 2/ were 15--25% dose/g, similar treatment with /sup 80m/Br as sodium bromide showed uniform low concentrations in all tissues at about the levels seen in blood. The effective specific activity of (/sup 80m/Br)BrBHPE, assayed by specific binding to ER in rat uterine cytosol, was 8700 Ci/mmole. 23 refs., 9 figs., 2 tabs.

  5. Experimentally accessible signatures of Auger scattering in graphene

    Science.gov (United States)

    Winzer, Torben; Jago, Roland; Malic, Ermin

    2016-12-01

    The gapless and linear electronic band structure of graphene opens up Auger scattering channels bridging the valence and the conduction band and changing the charge carrier density. Here, we reveal experimentally accessible signatures of Auger scattering in optically excited graphene. To be able to focus on signatures of Auger scattering, we apply a low excitation energy, weak pump fluences, and a cryostatic temperature, so that all relevant processes lie energetically below the optical phonon threshold. In this regime, carrier-phonon scattering is strongly suppressed and Coulomb processes govern the carrier dynamics. Depending on the excitation regime, we find an accumulation or depletion of the carrier occupation close to the Dirac point. This reflects well the behavior predicted from Auger-dominated carrier dynamics. Based on this observation, we propose a multicolor pump-probe experiment to uncover the extreme importance of Auger channels for the nonequilibrium dynamics in graphene.

  6. Auger-architectomics: introducing a new nanotechnology to infectious disease.

    Science.gov (United States)

    Swart, Chantel W; Pohl, Carolina H; Kock, Johan L F

    2014-01-01

    In 2010, we developed a new imaging nanotechnology called Auger-architectomics, to study drug biosensors in nano-detail. We succeeded in applying Auger atom electron physics coupled to scanning electron microscopy (SEM) and Argon-etching to cell structure exploration, thereby exposing a new dimension in structure and element composition architecture. Auger-architectomics was used to expose the fate and effect of drugs on cells. This technology should now be expanded to diseased cells. This paper will outline the development, proof of concept, and application of this imaging nanotechnology. A virtual tour is available at: http://vimeo.com/user6296337 .

  7. Single-electron detection and spectroscopy via relativistic cyclotron radiation

    Energy Technology Data Exchange (ETDEWEB)

    Asner, David M.; Bradley, Rich; De Viveiros Souza Filho, Luiz A.; Doe, Peter J.; Fernandes, Justin L.; Fertl, M.; Finn, Erin C.; Formaggio, Joseph; Furse, Daniel L.; Jones, Anthony M.; Kofron, Jared N.; LaRoque, Benjamin; Leber, Michelle; MCBride, Lisa; Miller, M. L.; Mohanmurthy, Prajwal T.; Monreal, Ben; Oblath, Noah S.; Robertson, R. G. H.; Rosenberg, Leslie; Rybka, Gray; Rysewyk, Devyn M.; Sternberg, Michael G.; Tedeschi, Jonathan R.; Thummler, Thomas; VanDevender, Brent A.; Woods, N. L.

    2015-04-01

    It has been understood since 1897 that accelerating charges should emit electromagnetic radiation. Cyclotron radiation, the particular form of radiation emitted by an electron orbiting in a magnetic field, was first derived in 1904. Despite the simplicity of this concept, and the enormous utility of electron spectroscopy in nuclear and particle physics, single-electron cyclotron radiation has never been observed directly. Here we demonstrate single-electron detection in a novel radiofrequency spectrometer. We observe the cyclotron radiation emitted by individual electrons that are produced with mildly-relativistic energies by a gaseous radioactive source and are magnetically trapped. The relativistic shift in the cyclotron frequency permits a precise electron energy measurement. Precise beta electron spectroscopy from gaseous radiation sources is a key technique in modern efforts to measure the neutrino mass via the tritium decay endpoint, and this work is a proof-of-concept for future neutrino mass experiments using this technique.

  8. Electron Effective-Attenuation-Length Database

    Science.gov (United States)

    SRD 82 NIST Electron Effective-Attenuation-Length Database (PC database, no charge)   This database provides values of electron effective attenuation lengths (EALs) in solid elements and compounds at selected electron energies between 50 eV and 2,000 eV. The database was designed mainly to provide EALs (to account for effects of elastic-eletron scattering) for applications in surface analysis by Auger-electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS).

  9. Detection of Nitric Oxide by Electron Paramagnetic Resonance Spectroscopy

    OpenAIRE

    Hogg, Neil

    2010-01-01

    Electron paramagnetic resonance (EPR) spectroscopy has been used in a number of ways to study nitric oxide chemistry and biology. As an intrinsically stable and relatively unreactive diatomic free radical, the challenges for detecting this species by EPR are somewhat different than those for transient radical species. This review gives a basic introduction to EPR spectroscopy and discusses its uses to assess and quantify nitric oxide formation in biological systems.

  10. Vibrational and optical spectroscopies integrated with environmental transmission electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Picher, Matthieu; Mazzucco, Stefano [Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, MD 20899-6203 (United States); Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, MD 20740 (United States); Blankenship, Steve [Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, MD 20899-6203 (United States); Sharma, Renu, E-mail: renu.sharma@nist.gov [Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, MD 20899-6203 (United States)

    2015-03-15

    Here, we present a measurement platform for collecting multiple types of spectroscopy data during high-resolution environmental transmission electron microscopy observations of dynamic processes. Such coupled measurements are made possible by a broadband, high-efficiency, free-space optical system. The critical element of the system is a parabolic mirror, inserted using an independent hollow rod and placed below the sample holder which can focus a light on the sample and/or collect the optical response. We demonstrate the versatility of this optical setup by using it to combine in situ atomic-scale electron microscopy observations with Raman spectroscopy. The Raman data is also used to measure the local temperature of the observed sample area. Other applications include, but are not limited to: cathodo- and photoluminescence spectroscopy, and use of the laser as a local, high-rate heating source. - Highlights: • Broadband, high-efficiency design adaptable to other electron microscopes. • Raman spectroscopy integrated with environmental transmission electron microscopy. • Raman spectra peak frequency shifts enable measurement of local sample temperature. • Multiple types of optical spectroscopy enabled, e.g. cathodoluminescence.

  11. Spectroscopy of nonequilibrium electrons and phonons

    CERN Document Server

    Shank, CV

    1992-01-01

    The physics of nonequilibrium electrons and phonons in semiconductors is an important branch of fundamental physics that has many practical applications, especially in the development of ultrafast and ultrasmall semiconductor devices. This volume is devoted to different trends in the field which are presently at the forefront of research. Special attention is paid to the ultrafast relaxation processes in bulk semiconductors and two-dimensional semiconductor structures, and to their study by different spectroscopic methods, both pulsed and steady-state. The evolution of energy and space distrib

  12. The Pierre Auger Observatory

    Energy Technology Data Exchange (ETDEWEB)

    Hojvat, C.

    1997-03-01

    The Pierre Auger Observatory is an international collaboration for the detailed study of the highest energy cosmic rays. It will operate at two similar sites, one in the northern hemisphere and one in the southern hemisphere. The Observatory is designed to collect a statistically significant data set of events with energies greater than 10{sup 19} eV and with equal exposures for the northern and southern skies.

  13. Scanning tunneling spectroscopy on electron-boson interactions in superconductors

    CERN Document Server

    Schackert, Michael Peter

    2015-01-01

    This work describes the experimental study of electron-boson interactions in superconductors by means of inelastic electron tunneling spectroscopy performed with a scanning tunneling microscope (STM) at temperatures below 1 K. This new approach allows the direct measurement of the Eliashberg function of conventional superconductors as demonstrated on lead (Pb) and niobium (Nb). Preparative experiments on unconventional iron-pnictides are presented in the end.

  14. Introduction to Spin Label Electron Paramagnetic Resonance Spectroscopy of Proteins

    Science.gov (United States)

    Melanson, Michelle; Sood, Abha; Torok, Fanni; Torok, Marianna

    2013-01-01

    An undergraduate laboratory exercise is described to demonstrate the biochemical applications of electron paramagnetic resonance (EPR) spectroscopy. The beta93 cysteine residue of hemoglobin is labeled by the covalent binding of 3-maleimido-proxyl (5-MSL) and 2,2,5,5-tetramethyl-1-oxyl-3-methyl methanethiosulfonate (MTSL), respectively. The excess…

  15. On the merits of conversion electron Mossbauer spectroscopy in geosciences

    DEFF Research Database (Denmark)

    Gunnlaugsson, H.P.; Bertelsen, P.; Budtz-Jørgensen, Carl

    2006-01-01

    Described are some applications of conversion electron Mossbauer spectroscopy (CEMS) in geosciences. It is shown how easily this technique can be applied in existing Mossbauer laboratories to investigate natural samples. Some examples demonstrate the kind of information CEMS can give on the weath...

  16. High-Resolution Conversion Electron Spectroscopy of Valence Electron Configurations (CESVEC) in Solids

    CERN Multimedia

    2002-01-01

    First measurements with the Zurich $\\beta$-spectrometer on sources from ISOLDE have demonstrated that high resolution spectroscopy of conversion electrons from valence shells is feasible.\\\\ \\\\ This makes possible a novel type of electron spectroscopy (CESVEC) on valence-electron configurations of tracer elements in solids. Thus the density of occupied electron states of impurities in solids has been measured for the first time. Such data constitute a stringent test of state-of-the-art calculations of impurity properties. Based on these results, we are conducting a systematic investigation of impurities in group IV and III-V semiconductors.

  17. Terahertz electromodulation spectroscopy of electron transport in GaN

    Energy Technology Data Exchange (ETDEWEB)

    Engelbrecht, S. G.; Arend, T. R.; Kersting, R., E-mail: roland.kersting@lmu.de [Photonics and Optoelectronics Group, Physics Department and Center for NanoScience (CeNS), Ludwig-Maximilians-Universität, Amalienstr. 54, 80799 München (Germany); Zhu, T.; Kappers, M. J. [Department of Materials Science and Metallurgy, University of Cambridge, Cambridge CB3 0FS (United Kingdom)

    2015-03-02

    Time-resolved terahertz (THz) electromodulation spectroscopy is applied to investigate the high-frequency transport of electrons in gallium nitride at different doping concentrations and densities of threading dislocations. At THz frequencies, all structures reveal Drude transport. The analysis of the spectral response provides the fundamental transport properties, such as the electron scattering time and the electrons' conductivity effective mass. We observe the expected impact of ionized-impurity scattering and that scattering at threading dislocations only marginally affects the high-frequency mobility.

  18. Terahertz electromodulation spectroscopy of electron transport in GaN

    Science.gov (United States)

    Engelbrecht, S. G.; Arend, T. R.; Zhu, T.; Kappers, M. J.; Kersting, R.

    2015-03-01

    Time-resolved terahertz (THz) electromodulation spectroscopy is applied to investigate the high-frequency transport of electrons in gallium nitride at different doping concentrations and densities of threading dislocations. At THz frequencies, all structures reveal Drude transport. The analysis of the spectral response provides the fundamental transport properties, such as the electron scattering time and the electrons' conductivity effective mass. We observe the expected impact of ionized-impurity scattering and that scattering at threading dislocations only marginally affects the high-frequency mobility.

  19. Examining Electron-Boson Coupling Using Time-Resolved Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Sentef, Michael; Kemper, Alexander F.; Moritz, Brian; Freericks, James K.; Shen, Zhi-Xun; Devereaux, Thomas P.

    2013-12-26

    Nonequilibrium pump-probe time-domain spectroscopies can become an important tool to disentangle degrees of freedom whose coupling leads to broad structures in the frequency domain. Here, using the time-resolved solution of a model photoexcited electron-phonon system, we show that the relaxational dynamics are directly governed by the equilibrium self-energy so that the phonon frequency sets a window for “slow” versus “fast” recovery. The overall temporal structure of this relaxation spectroscopy allows for a reliable and quantitative extraction of the electron-phonon coupling strength without requiring an effective temperature model or making strong assumptions about the underlying bare electronic band dispersion.

  20. (111)In-labeled trastuzumab (Herceptin) modified with nuclear localization sequences (NLS): an Auger electron-emitting radiotherapeutic agent for HER2/neu-amplified breast cancer.

    Science.gov (United States)

    Costantini, Danny L; Chan, Conrad; Cai, Zhongli; Vallis, Katherine A; Reilly, Raymond M

    2007-08-01

    ] for (111)In-NLS-trastuzumab and 1.1 %ID/g for (111)In-trastuzumab). (111)In-NLS-trastuzumab was 5- and 2-fold more potent at killing SK-BR-3 and MDA-MB-361 cells than (111)In-trastuzumab, respectively, whereas toxicity toward MDA-MB-231 cells was minimal. (111)In-NLS-trastuzumab was 6-fold more effective at killing SK-BR-3 cells than unlabeled trastuzumab. Formation of gammaH2AX foci occurred in a greater proportion of BC cells after incubation with (111)In-NLS-trastuzumab compared with (111)In-trastuzumab or unlabeled trastuzumab. NLS-peptides routed (111)In-trastuzumab to the nucleus of HER2/neu-positive human BC cells, rendering the radiopharmaceutical lethal to the cells through the emission of nanometer-micrometer range Auger electrons. The greater cytotoxic potency of (111)In-NLS-trastuzumab compared with unlabeled trastuzumab in vitro and its favorable tumor-targeting properties in vivo suggest that it could be an effective targeted radiotherapeutic agent for HER2/neu-amplified BC in humans.

  1. On the electronic configuration in Pu: spectroscopy and theory

    Energy Technology Data Exchange (ETDEWEB)

    Tobin, J G; Soderlind, P; Landa, A; Moore, K T; Schwartz, A J; Chung, B W; Wall, M; Wills, J M; Eriksson, O; Haire, R; Kutepov, A L

    2006-10-11

    Photoelectron spectroscopy, synchrotron-radiation-based x-ray absorption, electron energy-loss spectroscopy, and density-functional calculations within the mixed-level and magnetic models, together with canonical band theory have been used to study the electron configuration in Pu. These methods suggest a 5f{sup n} configuration for Pu of 5 {le} n < 6, with n {ne} 6, contrary to what has recently been suggested in several publications. We show that the n = 6 picture is inconsistent with the usual interpretation of photoemission and x-ray absorption spectra. Instead, these spectra support the traditional conjecture of a 5f{sup 5} configuration in Pu as is obtained by density-functional theory. We further argue, based on 5f-band filling, that an n = 6 hypothesis is incompatible with the position of Pu in the actinide series and its monoclinic ground-state phase.

  2. Molecular shock response of explosives: electronic absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Mcgrne, Shawn D [Los Alamos National Laboratory; Moore, David S [Los Alamos National Laboratory; Whitley, Von H [Los Alamos National Laboratory; Bolme, Cindy A [Los Alamos National Laboratory; Eakins, Daniel E [Los Alamos National Laboratory

    2009-01-01

    Electronic absorption spectroscopy in the range 400-800 nm was coupled to ultrafast laser generated shocks to begin addressing the question of the extent to which electronic excitations are involved in shock induced reactions. Data are presented on shocked polymethylmethacrylate (PMMA) thin films and single crystal pentaerythritol tetranitrate (PETN). Shocked PMMA exhibited thin film interference effects from the shock front. Shocked PETN exhibited interference from the shock front as well as broadband increased absorption. Relation to shock initiation hypotheses and the need for time dependent absorption data (future experiments) is briefly discussed.

  3. Probing battery chemistry with liquid cell electron energy loss spectroscopy.

    Science.gov (United States)

    Unocic, Raymond R; Baggetto, Loïc; Veith, Gabriel M; Aguiar, Jeffery A; Unocic, Kinga A; Sacci, Robert L; Dudney, Nancy J; More, Karren L

    2015-11-25

    We demonstrate the ability to apply electron energy loss spectroscopy (EELS) to follow the chemistry and oxidation states of LiMn2O4 and Li4Ti5O12 battery electrodes within a battery solvent. This is significant as the use and importance of in situ electrochemical cells coupled with a scanning/transmission electron microscope (S/TEM) has expanded and been applied to follow changes in battery chemistry during electrochemical cycling. We discuss experimental parameters that influence measurement sensitivity and provide a framework to apply this important analytical method to future in situ electrochemical studies.

  4. Chemical changes of titanium and titanium dioxide under electron bombardment

    Directory of Open Access Journals (Sweden)

    Romins Brasca

    2007-09-01

    Full Text Available The electron induced effect on the first stages of the titanium (Ti0 oxidation and titanium dioxide (Ti4+ chemical reduction processes has been studied by means of Auger electron spectroscopy. Using factor analysis we found that both processes are characterized by the appearance of an intermediate Ti oxidation state, Ti2O3 (Ti3+.

  5. In-beam conversion-electron spectroscopy of 180Hg

    Science.gov (United States)

    Page, R. D.; Andreyev, A. N.; Wiseman, D. R.; Butler, P. A.; Grahn, T.; Greenlees, P. T.; Herzberg, R.-D.; Huyse, M.; Jones, G. D.; Jones, P. M.; Joss, D. T.; Julin, R.; Juutinen, S.; Kankaanpää, H.; Keenan, A.; Kettunen, H.; Kuusiniemi, P.; Leino, M.; Muikku, M.; Nieminen, P.; Rahkila, P.; Rainovski, G. I.; Scholey, C.; Uusitalo, J.; van de Vel, K.; van Duppen, P.

    2011-09-01

    Excited states in 180Hg were populated using the 147Sm(36Ar,3n)180Hg reaction and studied by in-beam conversion-electron spectroscopy. Conversion electrons emitted at the target position were measured using the Silicon Array for Conversion Electron Detection (SACRED) spectrometer and tagged through the characteristic α decays of 180Hg detected in a position-sensitive silicon strip detector located at the focal plane of the gas-filled recoil separator Recoil Ion Transport Unit (RITU). Electron conversion of transitions previously assigned to 180Hg through in-beam γ-ray spectroscopy studies was identified up to the 10+→8+ transition and the intensities of the conversion-electron transitions were found to be consistent with the previous multipolarity assignments. Evidence was also found for two highly converted transitions in 180Hg: a 167 keV transition is interpreted as the transition from the newly identified 22+ state at 601 keV to the 21+ state at 434 keV, while a 420 keV transition is assigned as the E0 decay from the 0+ bandhead of the prolate-deformed configuration to the weakly deformed ground state.

  6. Double core-hole production in N2: beating the Auger clock.

    Science.gov (United States)

    Fang, L; Hoener, M; Gessner, O; Tarantelli, F; Pratt, S T; Kornilov, O; Buth, C; Gühr, M; Kanter, E P; Bostedt, C; Bozek, J D; Bucksbaum, P H; Chen, M; Coffee, R; Cryan, J; Glownia, M; Kukk, E; Leone, S R; Berrah, N

    2010-08-20

    We investigate the creation of double K-shell holes in N2 molecules via sequential absorption of two photons on a time scale shorter than the core-hole lifetime by using intense x-ray pulses from the Linac Coherent Light Source free electron laser. The production and decay of these states is characterized by photoelectron spectroscopy and Auger electron spectroscopy. In molecules, two types of double core holes are expected, the first with two core holes on the same N atom, and the second with one core hole on each N atom. We report the first direct observations of the former type of core hole in a molecule, in good agreement with theory, and provide an experimental upper bound for the relative contribution of the latter type.

  7. ¹¹¹In-Bn-DTPA-nimotuzumab with/without modification with nuclear translocation sequence (NLS) peptides: an Auger electron-emitting radioimmunotherapeutic agent for EGFR-positive and trastuzumab (Herceptin)-resistant breast cancer.

    Science.gov (United States)

    Fasih, Aisha; Fonge, Humphrey; Cai, Zhongli; Leyton, Jeffrey V; Tikhomirov, Ilia; Done, Susan J; Reilly, Raymond M

    2012-08-01

    Increased expression of epidermal growth factor receptors (EGFR) in breast cancer (BC) is often associated with trastuzumab (Herceptin)-resistant forms of the disease and represents an attractive target for novel therapies. Nimotuzumab is a humanized IgG(1) monoclonal antibody that is in clinical trials for treatment of EGFR-overexpressing malignancies. We show here that nimotuzumab derivatized with benzylisothiocyanate diethylenetriaminepentaacetic acid for labelling with the subcellular range Auger electron-emitter, (111)In and modified with nuclear translocation sequence (NLS) peptides ((111)In-NLS-Bn-DTPA-nimotuzumab) was bound, internalized and transported to the nucleus of EGFR-positive BC cells. Emission of Auger electrons in close proximity to the nucleus caused multiple DNA double-strand breaks which diminished the clonogenic survival (CS) of MDA-MB-468 cells that have high EGFR density (2.4 × 10(6) receptors/cell) to less than 3 %. (111)In-Bn-DTPA-nimotuzumab without NLS peptide modification was sevenfold less effective for killing MDA-MB-468 cells. (111)In-Bn-DTPA-nimotuzumab with/without NLS peptide modification were equivalently cytotoxic to MDA-MB-231 and TrR1 BC cells that have moderate EGFR density (5.4 × 10(5) or 4.2 × 10(5) receptors/cell, respectively) reducing their CS by twofold. MDA-MB-231 cells have intrinsic trastuzumab resistance due to low HER2 density, whereas TrR1 cells have acquired resistance despite HER2 overexpression. Biodistribution and microSPECT/CT imaging revealed that (111)In-NLS-Bn-DTPA-nimotuzumab exhibited more rapid elimination from the blood and lower tumour uptake than (111)In-Bn-DTPA-nimotuzumab. Tumour uptake of the radioimmunoconjugates in mice with MDA-MB-468 xenografts was high (8-16 % injected dose/g) and was blocked by administration of an excess of unlabelled nimotuzumab, demonstrating EGFR specificity. We conclude that (111)In-Bn-DTPA-nimotuzumab with/without NLS peptide modification are promising Auger

  8. Auger North: The Pierre Auger Observatory in the Northern Hemisphere

    Energy Technology Data Exchange (ETDEWEB)

    Mantsch, Paul M.; /Fermilab

    2009-01-01

    Results from Auger South have settled some fundamental issues about ultra-high energy (UHE) cosmic rays and made clear what is needed now to identify the sources of these particles, to uncover the acceleration process, to establish the particle types, and to test hadronic interaction properties at extreme energies. The cosmic rays above 55 EeV are key. Auger North targets this high energy frontier by increasing the collecting power of the Auger Observatory by a factor of eight for those high energy air showers. Particles above about 40 EeV have been shown to be subject to propagation energy loss, as predicted by Greisen, Zatsepin and Kuzmin (GZK) in 1966. Moreover, it is now evident that there is a detectable flux of particles from extragalactic sources within the GZK sphere. The inhomogeneous distribution of matter in the local universe imprints its anisotropy on the arrival directions of cosmic rays above 55 EeV. The challenge is to collect enough of those arrival directions to identify the class of astrophysical accelerators and measure directly the brightest sources. Auger North will increase the event rate from 25 per year to 200 per year and give the Auger Observatory full sky exposure. The Auger Observatory also has the capability to detect UHE photons and neutrinos from discrete sources or from the decays of GZK pions. With the expanded aperture of Auger North, the detection of GZK photons and neutrinos will provide a complementary perspective of the highest energy phenomena in the contemporary universe. Besides being an observatory for UHE cosmic rays, photons, and neutrinos, the Auger Observatory will serve as a laboratory for the study of hadronic interactions with good statistics over a wide range of center-of-mass energies above what can be reached at the LHC. Auger North will provide statistical power at center-of-mass energies above 250 TeV where the alternative extrapolations of hadronic cross sections diverge. Auger North is ready to go. The

  9. Femtosecond electron spectroscopy in an electron microscope with high brightness beams

    Science.gov (United States)

    Zhou, Faran; Williams, Joseph; Ruan, Chong-Yu

    2017-09-01

    A concept of performing femtosecond electron spectroscopy in an electron microscope with adaptive optics to handle space-charge-dominated beams is presented. Improved temporal-spectral resolutions are obtained through a combination of time and energy compression optics to disentangle the spectral information buried in temporally compressed pulses. A combined ∼1 eV-sub-ps performance with 105 electrons in single pulses, and femtosecond core-level spectroscopy at single-shots with higher doses are demonstrated. This strategy provides several orders of magnitude improvement in sensitivity compared to the state-of-the-art ultrafast electron microscopes, representing a flexible solution for studying electronic and chemical dynamics in complex systems overcoming the collective space-charge limitations.

  10. Multiple Auger decay probabilities of neon from the 1 s -core-hole state

    Science.gov (United States)

    Ma, Yulong; Zhou, Fuyang; Liu, Ling; Qu, Yizhi

    2017-10-01

    The multiple Auger decays of the Ne 1 s-1 state including double and triple Auger processes are investigated within the framework of perturbation theory. The contributions of the cascade and direct processes are determined for the double Auger decay. In the cascade processes, the choice of the orbital sets and configuration interaction can strongly affect the partial probabilities for the specific configurations of N e3 + . The multistep approaches, i.e., the knockout and shakeoff mechanisms, are implemented to deal with the direct double Auger processes for which the total and partial probabilities corresponding to specific configurations of N e3 + are calculated and reveal that the knockout is dominant. Finally, the probabilities of the triple Auger decays that are decomposed into a double Auger process and a subsequent emission of a single electron are obtained using the cascade and knockout mechanisms. The calculated probabilities agree reasonably well with the available experimental data.

  11. Femtosecond MeV Electron Energy-Loss Spectroscopy

    Science.gov (United States)

    Li, R. K.; Wang, X. J.

    2017-11-01

    Pump-probe electron energy-loss spectroscopy (EELS) with femtosecond temporal resolution will be a transformative research tool for studying nonequilibrium chemistry and electronic dynamics of matter. In this paper, we propose a concept of femtosecond EELS utilizing mega-electron-volt electron beams from a radio-frequency (rf) photocathode source. The high acceleration gradient and high beam energy of the rf gun are critical to the generation of 10-fs electron beams, which enables an improvement of the temporal resolution by more than 1 order of magnitude beyond the state of the art. In our proposal, the "reference-beam technique" relaxes the energy stability requirement of the rf power source by roughly 2 orders of magnitude. The requirements for the electron-beam quality, photocathode, spectrometer, and detector are also discussed. Supported by particle-tracking simulations, we demonstrate the feasibility of achieving sub-electron-volt energy resolution and approximately 10-fs temporal resolution with existing or near-future hardware performance.

  12. Two-dimensional electronic spectroscopy of anharmonic molecular potentials.

    Science.gov (United States)

    Anda, André; Abramavičius, Darius; Hansen, Thorsten

    2018-01-17

    Two-dimensional electronic spectroscopy (2DES) is a powerful tool in the study of coupled electron-phonon dynamics, yet very little is known about how nonlinearities in the electron-phonon coupling, arising from anharmonicities in the nuclear potentials, affect the spectra. These become especially relevant when the coupling is strong. From the linear spectroscopies, anharmonicities are known to give structure to the zero-phonon line and to break mirror-symmetry between absorption and emission, but the 2D analogues of these effects have not been identified. Using a simple two-level model where the electronic states are described by (displaced) harmonic oscillators with differing curvatures or displaced Morse oscillators, we find that the zero-phonon line shape is essentially transferred to the diagonal in 2DES spectra, and that anharmonicities break a horizontal mirror-symmetry in the infinite waiting time limit. We also identify anharmonic effects that are only present in 2DES spectra: twisting of cross-peaks stemming from stimulated emission signals; and oscillation period mismatch between ground state bleach and stimulated emission (for harmonic oscillators with differing curvatures), or inherently chaotic oscillations (for Morse oscillators). Our findings will facilitate an improved understanding of 2DES spectra and aid the interpretation of signals that are more realistic than those arising from simple models.

  13. Auger electron emitter against multiple myeloma - targeted endo-radio-therapy with {sup 125}I-labeled thymidine analogue 5-iodo-4'-thio-2'-deoxyuridine

    Energy Technology Data Exchange (ETDEWEB)

    Morgenroth, Agnieszka, E-mail: amorgenroth@ukaachen.de [Nuclear Medicine Clinic, University Ulm, Albert-Einstein-Allee 23, D-89081 Ulm (Germany); Nuclear Medicine Clinic, University Aachen, RWTH, Pauwelsstrasse 30, D-52074 Aachen (Germany); Dinger, Cornelia; Zlatopolskiy, Boris D.; Al-Momani, Ehab; Glatting, Gerhard [Nuclear Medicine Clinic, University Ulm, Albert-Einstein-Allee 23, D-89081 Ulm (Germany); Mottaghy, Felix M. [Nuclear Medicine Clinic, University Aachen, RWTH, Pauwelsstrasse 30, D-52074 Aachen (Germany); Reske, Sven N. [Nuclear Medicine Clinic, University Ulm, Albert-Einstein-Allee 23, D-89081 Ulm (Germany)

    2011-10-15

    Introduction: Multiple myeloma (MM) is a plasma cell malignancy characterized by accumulation of malignant, terminally differentiated B cells in the bone marrow. Despite advances in therapy, MM remains an incurable disease. Novel therapeutic approaches are, therefore, urgently needed. Auger electron-emitting radiopharmaceuticals are attractive for targeted nano-irradiation therapy, given that DNA of malignant cells is selectively addressed. Here we evaluated the antimyeloma potential of the Auger electron-emitting thymidine analogue {sup 125}I-labeled 5-iodo-4'-thio-2'-deoxyuridine ([{sup 125}I]ITdU). Methods: Cellular uptake and DNA incorporation of [{sup 125}I]ITdU were determined in fluorodeoxyuridine-pretreated KMS12BM, U266, dexamethasone-sensitive MM1.S and -resistant MM1.R cell lines. The effect of stimulation with interleukin 6 (IL6) or insulin-like growth factor 1 (IGF1) on the intracellular incorporation of [{sup 125}I]ITdU was investigated in cytokine-sensitive MM1.S and MM1.R cell lines. Apoptotic cells were identified using Annexin V. Cleavage of caspase 3 and PARP was visualized by Western blot. DNA fragmentation was investigated using laddering assay. Therapeutic efficiency of [{sup 125}I]ITdU was proven by clonogenic assay. Results: [{sup 125}I]ITdU was shown to be efficiently incorporated into DNA of malignant cells, providing a promising mechanism for delivering highly toxic Auger radiation emitters into tumor DNA. [{sup 125}I]ITdU had a potent antimyeloma effect in cell lines representing distinct disease stages and, importantly, in cell lines sensitive or resistant to the conventional therapeutic agent, but was not toxic for normal plasma and bone marrow stromal cells. Furthermore, [{sup 125}I]ITdU abrogated the protective actions of IL6 and IGF1 on MM cells. [{sup 125}I]ITdU induced massive damage in the DNA of malignant plasma cells, which resulted in efficient inhibition of clonogenic growth. Conclusion: These studies may provide a

  14. Utility of γH2AX as a molecular marker of DNA double-strand breaks in nuclear medicine: applications to radionuclide therapy employing auger electron-emitting isotopes.

    Science.gov (United States)

    Mah, Li-Jeen; Orlowski, Christian; Ververis, Katherine; El-Osta, Assam; Karagiannis, Tom C

    2011-01-01

    There is an intense interest in the development of radiopharmaceuticals for cancer therapy. In particular, radiopharmaceuticals which involve targeting radionuclides specifically to cancer cells with the use of monoclonal antibodies (radioimmunotherapy) or peptides (targeted radiotherapy) are being widely investigated. For example, the ultra-short range Auger electron-emitting isotopes, which are discussed in this review, are being considered in the context of DNAtargeted radiotherapy. The efficient quantitative evaluation of the levels of damage caused by such potential radiopharmaceuticals is required for assessment of therapeutic efficacy and determination of relevant doses for successful treatment. The DNA double-strand break surrogate marker, γH2AX, has emerged as a useful biomonitor of damage and thus effectiveness of treatment, offering a highly specific and sensitive means of assessment. This review will cover the potential applications of γH2AX in nuclear medicine, in particular radionuclide therapy.

  15. Electronic spectroscopy of jet-cooled YbNH3

    Science.gov (United States)

    Tonge, Nicola M.; Rusher, Cassandra A.; Bhalla, Nitika; Varriale, Luigi; Ellis, Andrew M.

    2012-02-01

    We report the first spectroscopic study of a complex consisting of a rare earth atom in combination with ammonia. Using two-color resonance-enhanced multiphoton ionization (REMPI) spectroscopy, the lowest energy electronic transition of YbNH3 has been found in the near-infrared. The spectrum arises from a spin-forbidden transition between the 1A1 ground electronic state and the lowest 3E excited electronic state. The transition is metal centered and approximately correlates with the Yb 6s6p 3P ← 6s2 1S transition. The observation of clear spin-orbit structure in the spectrum confirms the C3v symmetry of YbNH3. Vibrational structure is also observed in the REMPI spectrum, which is dominated by excitation of the Yb-N stretching vibration.

  16. Probing Nanoscale Electronic and Magnetic Interaction with Scanning Tunneling Spectroscopy

    DEFF Research Database (Denmark)

    Bork, Jakob

    This thesis is concerned with fundamental research into electronic and magnetic interaction on the nanoscale. From small metallic and magnetic islands and layers to single atoms. The research revolves around magnetic interaction probed through the spectroscopic capabilities of the scanning....... This is related to research in correlated electron materials such as studies of phase transitions in heavy fermion compounds and magnetic interaction in spintronic research. The capping of cobalt islands on Cu(111) with silver is investigated with STM and photoemission spectroscopy. It is shown that at low...... coverage the silver preferably nucleates on top of the bilayer high cobalt islands compared to directly on the Cu(111) substrate. Furthermore, the silver forms a combination of a reconstruction and a Moire pattern which is investigated with low-energy electron diraction and spectroscopic STM mapping at 6...

  17. 2012 ELECTRONIC SPECTROSCOPY & DYNAMICS GORDON RESEARCH CONFERENCE, JULY 22-27, 2012

    Energy Technology Data Exchange (ETDEWEB)

    Kohler, Bern

    2012-07-27

    Topics covered in this GRC include high-resolution spectroscopy, coherent electronic energy transport in biology, excited state theory and dynamics, excitonics, electronic spectroscopy of cold and ultracold molecules, and the spectroscopy of nanostructures. Several sessions will highlight innovative techniques such as time-resolved x-ray spectroscopy, frequency combs, and liquid microjet photoelectron spectroscopy that have forged stimulating new connections between gas-phase and condensed-phase work.

  18. THz Electron Paramagnetic Resonance / THz Spectroscopy at BESSY II

    Directory of Open Access Journals (Sweden)

    Karsten Holldack

    2016-02-01

    Full Text Available The THz beamline at BESSY II employs high power broadband femto- to picosecond long THz pulses for magneto-optical THz and FIR studies. A newly designed set-up exploits the unique properties of ultrashort THz pulses generated by laser-energy modulation of electron bunches in the storage ring or alternatively from compressed electron bunches. Experiments from 0.15 to 5 THz (~ 5 – 150 cm-1 may be conducted at a user station equipped with a fully evacuated high resolution FTIR spectrometer (0.0063 cm-1, lHe cooled bolometer detectors, a THz TDS set-up and different sample environments, including a superconducting high field magnet (+11 T - 11T with variable temperature insert (1.5 K – 300 K, a sample cryostat and a THz attenuated total reflection chamber.  Main applications are Frequency Domain Fourier transform THz-Electron Paramagnetic Resonance (FD-FT THz-EPR, THz-FTIR spectroscopy and optical pump - THz probe time domain spectroscopy (TDS, with sub-ps time resolution.

  19. Correlating the motion of electrons and nuclei with two-dimensional electronic-vibrational spectroscopy.

    Science.gov (United States)

    Oliver, Thomas A A; Lewis, Nicholas H C; Fleming, Graham R

    2014-07-15

    Multidimensional nonlinear spectroscopy, in the electronic and vibrational regimes, has reached maturity. To date, no experimental technique has combined the advantages of 2D electronic spectroscopy and 2D infrared spectroscopy, monitoring the evolution of the electronic and nuclear degrees of freedom simultaneously. The interplay and coupling between the electronic state and vibrational manifold is fundamental to understanding ensuing nonradiative pathways, especially those that involve conical intersections. We have developed a new experimental technique that is capable of correlating the electronic and vibrational degrees of freedom: 2D electronic-vibrational spectroscopy (2D-EV). We apply this new technique to the study of the 4-(di-cyanomethylene)-2-methyl-6-p-(dimethylamino)styryl-4H-pyran (DCM) laser dye in deuterated dimethyl sulfoxide and its excited state relaxation pathways. From 2D-EV spectra, we elucidate a ballistic mechanism on the excited state potential energy surface whereby molecules are almost instantaneously projected uphill in energy toward a transition state between locally excited and charge-transfer states, as evidenced by a rapid blue shift on the electronic axis of our 2D-EV spectra. The change in minimum energy structure in this excited state nonradiative crossing is evident as the central frequency of a specific vibrational mode changes on a many-picoseconds timescale. The underlying electronic dynamics, which occur on the hundreds of femtoseconds timescale, drive the far slower ensuing nuclear motions on the excited state potential surface, and serve as a excellent illustration for the unprecedented detail that 2D-EV will afford to photochemical reaction dynamics.

  20. Hypernuclear spectroscopy with electron beam at JLab Hall C

    Energy Technology Data Exchange (ETDEWEB)

    Yuu Fujii

    2010-12-01

    Hypernuclear spectroscopy with electron beam at JLab Hall C has been studied since 2000. The first experiment, JLab E89-009, used Short Orbit Spectrometer (SOS) as a kaon arm and a split-pole type spectrometer (ENGE) as an electron arm. E89-009 employed zero-degree tagging method, which tags scattered electrons at zero-degree and the kaon arm also covered zero-degree. This method obtains maximum yield of hypernuclei but sufferers from high rate background of electrons from bremsstrahlung and positrons from pair-creation. Nevertheless, this experiment demonstrated the possibility of the (e,e' K{sup +}) reaction for hypernuclear spectroscopy by obtaining a hypernuclear mass spectrum with an energy resolution of better than 1 MeV (FWHM) [1][2]. However, poor signal to noise ratio and poor statistics requires us to improve the experimental setup. Therefore, E01-011 experiment was proposed based on the success of the JLab E01-011 experiment. Improvements of E01-011 from E09-009 can be summarized as: 1. Employed newly constructed high resolution kaon spectrometer (HKS) as a kaon arm. 2. Employed so-called 'tilt-method' for the electron arm. With the newly constructed HKS, having 2-10-4 momentum resolution, we expect an energy resolution of 400 keV (FWHM). The 'tilt-method' means the electron arm is tilted vertically to the splitter dispersive plane to avoid background electrons from bremsstrahlung and moeller scattering. The setup allowed us to use up to a few tens beam. The experiment was performed in 2005 and final result will be shown shortly. The third experiment, JLab E05-115 experiment was proposed as a natural extension of E01-011 experiment and will be performed in 2009. Improvements of experimental setup are, 1. Employed newly constructed high resolution electron spectrometer (HES) as a electron arm, 2. Employed a new charge-separation magnet (Splitter), fully customized for hypernuclear experiment at Hall C. With the third generation

  1. MCDF calculations of Auger cascade processes

    Science.gov (United States)

    Beerwerth, Randolf; Fritzsche, Stephan

    2017-10-01

    We model the multiple ionization of near-neutral core-excited atoms where a cascade of Auger processes leads to the emission of several electrons. We utilize the multiconfiguration Dirac-Fock (MCDF) method to generate approximate wave functions for all fine-structure levels and to account for all decays between them. This approach allows to compute electron spectra, the population of final-states and ion yields, that are accessible in many experiments. Furthermore, our approach is based on the configuration interaction method. A careful treatment of correlation between electronic configurations enables one to model three-electron processes such as an Auger decay that is accompanied by an additional shake-up transition. Here, this model is applied to the triple ionization of atomic cadmium, where we show that the decay of inner-shell 4p holes to triply-charged final states is purely due to the shake-up transition of valence 5s electrons. Contribution to the Topical Issue "Atomic and Molecular Data and their Applications", edited by Gordon W.F. Drake, Jung-Sik Yoon, Daiji Kato, Grzegorz Karwasz.

  2. Electron momentum spectroscopy study of amantadine: binding energy spectra and valence orbital electron density distributions

    Science.gov (United States)

    Litvinyuk, I. V.; Zheng, Y.; Brion, C. E.

    2000-11-01

    The electron binding energy spectrum and valence orbital electron momentum density distributions of amantadine (1-aminoadamantane), an important anti-viral and anti-Parkinsonian drug, have been measured by electron momentum spectroscopy. Theoretical momentum distributions, calculated at the 6-311++G** and AUG-CC-PVTZ levels within the target Hartree-Fock and also the target Kohn-Sham density functional theory approximations, show good agreement with the experimental results. The results for amantadine are also compared with those for the parent molecule, adamantane, reported earlier (Chem. Phys. 253 (2000) 41). Based on the comparison tentative assignments of the valence region ionization bands of amantadine have been made.

  3. Inexpensive electronics and software for photon statistics and correlation spectroscopy.

    Science.gov (United States)

    Gamari, Benjamin D; Zhang, Dianwen; Buckman, Richard E; Milas, Peker; Denker, John S; Chen, Hui; Li, Hongmin; Goldner, Lori S

    2014-07-01

    Single-molecule-sensitive microscopy and spectroscopy are transforming biophysics and materials science laboratories. Techniques such as fluorescence correlation spectroscopy (FCS) and single-molecule sensitive fluorescence resonance energy transfer (FRET) are now commonly available in research laboratories but are as yet infrequently available in teaching laboratories. We describe inexpensive electronics and open-source software that bridges this gap, making state-of-the-art research capabilities accessible to undergraduates interested in biophysics. We include a discussion of the intensity correlation function relevant to FCS and how it can be determined from photon arrival times. We demonstrate the system with a measurement of the hydrodynamic radius of a protein using FCS that is suitable for the undergraduate teaching laboratory. The FPGA-based electronics, which are easy to construct, are suitable for more advanced measurements as well, and several applications are described. As implemented, the system has 8 ns timing resolution, can control up to four laser sources, and can collect information from as many as four photon-counting detectors.

  4. First test results from the Front-End Board with Cyclone V as a test high-resolution platform for the Auger-Beyond-2015 Front End Electronics

    Energy Technology Data Exchange (ETDEWEB)

    Szadkowski, Zbigniew [University of Lodz, Department of Physics and Applied Informatics, Faculty of High-Energy Astrophysics, 90-236 Lodz, Pomorska 149, (Poland)

    2015-07-01

    The paper presents the first results from the Front- End Board (FEB) with the biggest Cyclone{sup R} V E FPGA 5CEFA9F31I7N, supporting 8 channels sampled up to 250 MSps at 14-bit resolution. Considered sampling for the SD is 120 MSps, however, the FEB has been developed with external anti-aliasing filters to keep a maximal flexibility. Six channels are targeted to the SD, two the rest for other experiments like: Auger Engineering Radio Array and additional muon counters. More channels and higher sampling generate larger size of registered events. We used the standard radio channel for a radio transmission from the detectors to the Central Data Acquisition Station (CDAS) to avoid at present a significant modification of a software in both sides: the detector and the CDAS (planned in a future for a final design). Seven FEBs have been deployed in the test detectors on a dedicated Engineering Array in a hexagon. Several variants of the FPGA code were tested for 120, 160, 200 and even 240 MSps DAQ. Tests confirmed a stability and reliability of the FEB design in real pampas conditions with more than 40 deg. C daily temperature variation and a strong sun exposition with a limited power budget only from a single solar panel. (authors)

  5. Single-photon double and triple ionization of acetaldehyde (ethanal) studied by multi-electron coincidence spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Zagorodskikh, S. [Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20 Uppsala (Sweden); Department of Physics, University of Gothenburg, Origovägen 6B, SE-412 96 Gothenburg (Sweden); Zhaunerchyk, V. [Department of Physics, University of Gothenburg, Origovägen 6B, SE-412 96 Gothenburg (Sweden); Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20 Uppsala (Sweden); Mucke, M. [Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20 Uppsala (Sweden); Eland, J.H.D. [Department of Chemistry, Physical and Theoretical Chemistry Laboratory, Oxford University, South Parks Road, Oxford OX1 3QZ (United Kingdom); Department of Physics, University of Gothenburg, Origovägen 6B, SE-412 96 Gothenburg (Sweden); Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20 Uppsala (Sweden); Squibb, R.J. [Department of Physics, University of Gothenburg, Origovägen 6B, SE-412 96 Gothenburg (Sweden); Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20 Uppsala (Sweden); Karlsson, L. [Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20 Uppsala (Sweden); Linusson, P. [Department of Physics, Stockholm University, AlbaNova University Center, SE-106 91 Stockholm (Sweden); Feifel, R., E-mail: raimund.feifel@gu.se [Department of Physics, University of Gothenburg, Origovägen 6B, SE-412 96 Gothenburg (Sweden); Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20 Uppsala (Sweden)

    2015-12-16

    Highlights: • The first ever valence double ionization spectrum of acetaldehyde is reported. • The first ever site-selectively extracted Auger spectra of acetaldehyde are reported. • The first ever Auger spectra of acetaldehyde involving shake-up states are reported. • The first ever triple ionization spectra of acetaldehyde are reported. • The first ever energy sharing of electron pairs emitted by acetaldehyde is presented. - Abstract: Single-photon multiple ionization processes of acetaldehyde (ethanal) have been experimentally investigated by utilizing a multi-particle coincidence technique based on the time-of-flight magnetic bottle principle, in combination with either a synchrotron radiation source or a pulsed helium discharge lamp. The processes investigated include double and triple ionization in the valence region as well as single and double Auger decay of core-ionized acetaldehyde. The latter are studied site-selectively for chemically different carbon core vacancies, scrutinizing early theoretical predictions specifically made for the case of acetaldehyde. Moreover, Auger processes in shake-up and core-valence ionized states are investigated. In the cases where the processes involve simultaneous emission of two electrons, the distributions of the energy sharing are presented, emphasizing either the knock-out or shake-off mechanism.

  6. LiMn2O4 Surface Chemistry Evolution during Cycling Revealed by in Situ Auger Electron Spectroscopy and X-ray Photoelectron Spectroscopy.

    Science.gov (United States)

    Tang, Ching-Yen; Leung, Kevin; Haasch, Richard T; Dillon, Shen J

    2017-10-04

    This work utilizes in situ electrochemical and analytical characterization during cycling of LiMn2O4 (LMO) equilibrated at different potentials in an ultrahigh vacuum (UHV) environment. The LMO reacts with organic molecules in the vacuum to form a high surface concentration of Li2CO3 (≈50% C) during initial charging to 4.05 V. Charging to higher potentials reduces the overall Li2CO3 concentration (≈15% C). Discharging to 3.0 V increases the Li2CO3 concentration (≈30% C) and over discharging to 0.1 V again reduces its concentration (≈15% C). This behavior is reproducible over 5 cycles. The model geometry utilized suggests that oxygen from LMO can participate in redox of carbon, where LMO contributes oxygen to form the carbonate in the solid electrolyte interphase (SEI). Similar results were obtained from samples cycled ex situ, suggesting that the model in situ geometry provides reasonably representative information about surface chemistry evolution. Carbon redox at LMO and the inherent voltage instability of the Li2CO3 likely contributes significantly to its capacity fade.

  7. Room- and low-temperature assessment of pseudomorphic AlGaAs/InGaAs/GaAS high-electron-mobility transistor structures by photoluminescence spectroscopy

    Science.gov (United States)

    Gilperez, J. M.; Sanchez-Rojas, J. L.; Munoz, E.; Calleja, E.; David, J. P. R.; Reddy, M.; Hill, G.; Sanchez-Dehesa, J.

    1994-11-01

    The use of room- and low-temperature photoluminescence (PL) spectroscopy for the assessment of n-type pseudomorphic AlGaAs/InGaAs/GaAs high-electron-mobility transistor stransitor structures is reported. We describe a method to determine the InAs mole fraction x, the channel layer thickness L, and the confined two-dimensional electron gas density (n(sub s)), based on the comparison between the PL transitions and the recombination energies derived from self-consistent calculations of the subband structure. A detailed analysis of the optical transitions and their dependence on the Fermi level position and temperature is performed. It is shown that, in real devices, the high sensitivity of the recombination energies and intensities on small changes of the parameters x, L, and n(sub s) allows us to detect deviations from their nominal structural parameters within the uncertainty of the molecular beam epitaxy growth technique. The present assessment procedure has been applied to a significant number of samples, and it has been backed by independent measurements of these parameters by more sophisticated techniques such as Shubnikov-de Haas and PL excitation in standard and gated samples, and by physical techniques like transmission electron microscopy and Auger spectroscopy.

  8. Optimization of Auger System in Shallow Electromechanical Auger Drills

    Science.gov (United States)

    Hong, Jialin; Talalay, Pavel

    2017-04-01

    In recent decades, electromechanical auger drilling has become a very popular method of ice core sampling, and the drilling sites are spread all over the world, covering the whole glacial distribution from polar to high-mountain regions. However, auger systems were usually determined by experience, and the main parameters (helix angle of the fights and rotational speed) are varied in a wide range from drill to drill. The external parameters which have a large influence on the efficiency of the cuttings transportation are friction coefficients between ice inner/outer barrels and the size distribution of ice cuttings. Totally 424 linear friction experiments with common and promising slider materials for auger drills were carried out at the wide range of temperatures observed in glaciers from -60 to 0 C. The coefficient of friction increases with decreasing of temperature but this dependence is not monotonous. To determine the patterns of ice cuttings, sixteen ice cuttings were sampled in the course of drilling in natural lake ice. The size distribution of the cuttings has an asymmetrical shape. Approximately half of the ice cuttings by weight are classified as small sized (sieving samples, the ice cuttings have prolate form with a ratio between the major and minor axis 1.55 in average. In order to choose the optimal auger parameters, the discrete element method is used to analyze the performance of cuttings transportation for different rotation speeds in the range 50-200 rpm and auger angles in the range 25-45°. Validation of optimal auger system were undertaken by field testes at high elevation glacier (5600m) in Xinjiang, China.

  9. El proyecto AUGER

    Science.gov (United States)

    Etchegoyen, A.

    Hace ya más de 30 años en Volcano Ranch, EE.UU., un extenso chubasco cósmico (ECC) fue detectado con energía en exceso de 1020 eV. Desde entonces, observatorios ubicados en Haverah Park del Reino Unido, Yakutsk de Rusia, AGASA de Japón y Dugway de EE.UU. también han observado ECC con energías mayores que 1020 eV. Poco se sabe de dichos rayos, y en particular cuál es la naturaleza del primario, de dónde provienen, y cómo son acelerados, pero su naturaleza ultrarelativista excluye la mayoría de las respuestas dejando sólo algunas plausibles de ser investigadas experimentalmente. Grupos de científicos de 20 países están trabajando con el fin de construir dos arreglos de detectores gigantes, uno en cada hemisferio a lo largo de 3000 km2 c/u. Dichas dimensiones son necesarias debido al flujo estimado de 1 rayo cósmico/centuria/km2/sr. La sede del Observatorio del Sur es la Argentina. El proyecto fue nombrado Pierre Auger en conmemoración del célebre físico francés que detectó por primera vez chubascos cósmicos en 1938. El proyecto focaliza su interés en rayos cósmicos con energías mayores que 1020 eV.

  10. The Pierre Auger Observatory Upgrade - Preliminary Design Report

    Energy Technology Data Exchange (ETDEWEB)

    Aab, Alexander [Univ. Siegen (Germany); et al.

    2016-04-12

    The Pierre Auger Observatory has begun a major Upgrade of its already impressive capabilities, with an emphasis on improved mass composition determination using the surface detectors of the Observatory. Known as AugerPrime, the upgrade will include new 4 m2 plastic scintillator detectors on top of all 1660 water-Cherenkov detectors, updated and more flexible surface detector electronics, a large array of buried muon detectors, and an extended duty cycle for operations of the fluorescence detectors. This Preliminary Design Report was produced by the Collaboration in April 2015 as an internal document and information for funding agencies. It outlines the scientific and technical case for AugerPrime. We now release it to the public via the arXiv server. We invite you to review the large number of fundamental results already achieved by the Observatory and our plans for the future.

  11. Handbook of Applied Solid State Spectroscopy

    CERN Document Server

    Vij, D. R

    2006-01-01

    Solid-State spectroscopy is a burgeoning field with applications in many branches of science, including physics, chemistry, biosciences, surface science, and materials science. Handbook of Applied Solid-State Spectroscopy brings together in one volume information about various spectroscopic techniques that is currently scattered in the literature of these disciplines. This concise yet comprehensive volume covers theory and applications of a broad range of spectroscopies, including NMR, NQR, EPR/ESR, ENDOR, scanning tunneling, acoustic resonance, FTIR, auger electron emission, x-ray photoelectron emission, luminescence, and optical polarization, and more. Emphasis is placed on fundamentals and current methods and procedures, together with the latest applications and developments in the field.

  12. Electronic structure of atoms: atomic spectroscopy information system

    Science.gov (United States)

    Kazakov, V. V.; Kazakov, V. G.; Kovalev, V. S.; Meshkov, O. I.; Yatsenko, A. S.

    2017-10-01

    The article presents a Russian atomic spectroscopy, information system electronic structure of atoms (IS ESA) (http://grotrian.nsu.ru), and describes its main features and options to support research and training. The database contains over 234 000 records, great attention paid to experimental data and uniform filling of the database for all atomic numbers Z, including classified levels and transitions of rare earth and transuranic elements and their ions. Original means of visualization of scientific data in the form of spectrograms and Grotrian diagrams have been proposed. Presentation of spectral data in the form of interactive color charts facilitates understanding and analysis of properties of atomic systems. The use of the spectral data of the IS ESA together with its functionality is effective for solving various scientific problems and training of specialists.

  13. Two-dimensional electronic spectroscopy with birefringent wedges

    Energy Technology Data Exchange (ETDEWEB)

    Réhault, Julien; Maiuri, Margherita; Oriana, Aurelio; Cerullo, Giulio [IFN-CNR, Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano (Italy)

    2014-12-15

    We present a simple experimental setup for performing two-dimensional (2D) electronic spectroscopy in the partially collinear pump-probe geometry. The setup uses a sequence of birefringent wedges to create and delay a pair of phase-locked, collinear pump pulses, with extremely high phase stability and reproducibility. Continuous delay scanning is possible without any active stabilization or position tracking, and allows to record rapidly and easily 2D spectra. The setup works over a broad spectral range from the ultraviolet to the near-IR, it is compatible with few-optical-cycle pulses and can be easily reconfigured to two-colour operation. A simple method for scattering suppression is also introduced. As a proof of principle, we present degenerate and two-color 2D spectra of the light-harvesting complex 1 of purple bacteria.

  14. Superposition Principle in Auger Recombination of Charged and Neutral Multicarrier States in Semiconductor Quantum Dots.

    Science.gov (United States)

    Wu, Kaifeng; Lim, Jaehoon; Klimov, Victor I

    2017-08-22

    Application of colloidal semiconductor quantum dots (QDs) in optical and optoelectronic devices is often complicated by unintentional generation of extra charges, which opens fast nonradiative Auger recombination pathways whereby the recombination energy of an exciton is quickly transferred to the extra carrier(s) and ultimately dissipated as heat. Previous studies of Auger recombination have primarily focused on neutral and, more recently, negatively charged multicarrier states. Auger dynamics of positively charged species remains more poorly explored due to difficulties in creating, stabilizing, and detecting excess holes in the QDs. Here we apply photochemical doping to prepare both negatively and positively charged CdSe/CdS QDs with two distinct core/shell interfacial profiles ("sharp" versus "smooth"). Using neutral and charged QD samples we evaluate Auger lifetimes of biexcitons, negative and positive trions (an exciton with an extra electron or a hole, respectively), and multiply negatively charged excitons. Using these measurements, we demonstrate that Auger decay of both neutral and charged multicarrier states can be presented as a superposition of independent elementary three-particle Auger events. As one of the manifestations of the superposition principle, we observe that the biexciton Auger decay rate can be presented as a sum of the Auger rates for independent negative and positive trion pathways. By comparing the measurements on the QDs with the "sharp" versus "smooth" interfaces, we also find that while affecting the absolute values of Auger lifetimes, manipulation of the shape of the confinement potential does not lead to violation of the superposition principle, which still allows us to accurately predict the biexciton Auger lifetimes based on the measured negative and positive trion dynamics. These findings indicate considerable robustness of the superposition principle as applied to Auger decay of charged and neutral multicarrier states

  15. Attosecond photoelectron spectroscopy of electron transport in solids

    Energy Technology Data Exchange (ETDEWEB)

    Magerl, Elisabeth

    2011-03-31

    Time-resolved photoelectron spectroscopy of condensed matter systems in the attosecond regime promises new insights into excitation mechanisms and transient dynamics of electrons in solids. This timescale became accessible directly only recently with the development of the attosecond streak camera and of laser systems providing few-cycle, phase-controlled laser pulses in the near-infrared, which are used to generate isolated, sub-femtosecond extreme-ultraviolet pulses with a well-defined timing with respect to the near-infrared pulse. Employing these pulses, the attosecond streak camera offers time resolutions as short as a few 10 attoseconds. In the framework of this thesis, a new, versatile experimental apparatus combining attosecond pulse generation in gases with state of the art surface science techniques is designed, constructed, and commissioned. Employing this novel infrastructure and the technique of the attosecond transient recorder, we investigate transport phenomena occurring after photoexcitation of electrons in tungsten and rhenium single crystals and show that attosecond streaking is a unique method for resolving extremely fast electronic phenomena in solids. It is demonstrated that electrons originating from different energy levels, i.e. from the conduction band and the 4f core level, are emitted from the crystal surface at different times. The origin of this time delay, which is below 150 attoseconds for all studied systems, is investigated by a systematic variation of several experimental parameters, in particular the photon energy of the employed attosecond pulses. These experimental studies are complemented by theoretical studies of the group velocity of highly-excited electrons based on ab initio calculations. While the streaking technique applied on single crystals can provide only information about the relative time delay between two types of photoelectrons, the absolute transport time remains inaccessible. We introduce a scheme of a reference

  16. Inner-shell spectroscopy and exchange interaction of Rydberg electrons bound by singly and doubly charged Kr and Xe atoms in small clusters

    Energy Technology Data Exchange (ETDEWEB)

    Nagasaka, Masanari; Hatsui, Takaki; Setoyama, Hiroyuki; Ruehl, Eckart [Institute for Molecular Science, Myodaiji, Okazaki 444-8585 (Japan); Kosugi, Nobuhiro, E-mail: kosugi@ims.ac.j [Institute for Molecular Science, Myodaiji, Okazaki 444-8585 (Japan)

    2011-01-15

    Surface-site resolved Kr 3d{sub 5/2}{sup -1}5p and 3d{sub 5/2}{sup -1}6p and Xe 4d{sub 5/2}{sup -1}6p and 4d{sub 5/2}{sup -1}7p Rydberg excited states in small van der Waals Kr and Xe clusters with a mean size of = 15 are investigated by X-ray absorption spectroscopy. Furthermore, surface-site resolved Kr 4s{sup -2}5p, 4s{sup -2}6p, and 4s{sup -1}4p{sup -1}5p shakeup-like Rydberg states in small Kr clusters are investigated by resonant Auger electron spectroscopy. The exchange interaction of the Rydberg electron with the surrounding atoms and the induced polarization of the surrounding atoms in the singly and doubly ionized atoms are deduced from the experimental spectra to analyze different surface-site contributions in small clusters, assuming that the corner, edge, face, and bulk sites have 3, 5-6, 8, and 12 nearest neighbor atoms. These energies are almost proportional to the number of the nearest neighbor atoms. The present analysis indicates that small Kr and Xe clusters with = 15 have an average or mixture structure between the fcc-like cubic and icosahedron-like spherical structures.

  17. Annular electron energy-loss spectroscopy in the scanning transmission electron microscope

    Energy Technology Data Exchange (ETDEWEB)

    Ruben, Gary [School of Physics, University of Melbourne, Parkville, Victoria 3010 (Australia); Bosman, Michel [Institute of Materials Research and Engineering, A-STAR (Agency for Science, Technology and Research), 3 Research Link, Singapore 117602 (Singapore); D' Alfonso, Adrian J. [School of Physics, University of Melbourne, Parkville, Victoria 3010 (Australia); Okunishi, Eiji; Kondo, Yukihito [JEOL Ltd., 1-2, Musashino 3-chome Akishima, Tokyo 196-8558 (Japan); Allen, Leslie J., E-mail: lja@unimelb.edu.au [School of Physics, University of Melbourne, Parkville, Victoria 3010 (Australia)

    2011-11-15

    We study atomic-resolution annular electron energy-loss spectroscopy (AEELS) in scanning transmission electron microscopy (STEM) imaging with experiments and numerical simulations. In this technique the central part of the bright field disk is blocked by a beam stop, forming an annular entry aperture to the spectrometer. The EELS signal thus arises only from electrons scattered inelastically to angles defined by the aperture. It will be shown that this method is more robust than conventional EELS imaging to variations in specimen thickness and can also provide higher spatial resolution. This raises the possibility of lattice resolution imaging of lighter elements or ionization edges previously considered unsuitable for EELS imaging. -- Highlights: Black-Right-Pointing-Pointer We study annular electron energy-loss spectroscopy (AEELS) in STEM. Black-Right-Pointing-Pointer This is more robust to changes in specimen thickness than conventional EELS. Black-Right-Pointing-Pointer AEELS provides higher spatial resolution than conventional EELS. Black-Right-Pointing-Pointer This raises the possibility of lattice resolution imaging of lighter elements.

  18. Two-Dimensional Electronic Spectroscopies for Probing Electronic Structure and Charge Transfer: Applications to Photosystem II

    Energy Technology Data Exchange (ETDEWEB)

    Ogilvie, Jennifer P. [Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Physics

    2016-11-22

    Photosystem II (PSII) is the only known natural enzyme that uses solar energy to split water, making the elucidation of its design principles critical for our fundamental understanding of photosynthesis and for our ability to mimic PSII’s remarkable properties. This report discusses progress towards addressing key open questions about the PSII RC. It describes new spectroscopic methods that were developed to answer these questions, and summarizes the outcomes of applying these methods to study the PSII RC. Using 2D electronic spectroscopy and 2D electronic Stark spectroscopy, models for the PSII RC were tested and refined. Work is ongoing to use the collected data to elucidate the charge separation mechanism in the PSII RC. Coherent dynamics were also observed in the PSII RC for the first time. Through extensive characterization and modeling we have assigned these coherences as vibronic in nature, and believe that they reflect resonances between key vibrational pigment modes and electronic energy gaps that may facilitate charge separation. Work is ongoing to definitively test the functional relevance of electronic-vibrational resonances.

  19. Valence electron energy-loss spectroscopy in monochromated scanning transmission electron microscopy.

    Science.gov (United States)

    Erni, Rolf; Browning, Nigel D

    2005-10-01

    With the development of monochromators for (scanning) transmission electron microscopes, valence electron energy-loss spectroscopy (VEELS) is developing into a unique technique to study the band structure and optical properties of nanoscale materials. This article discusses practical aspects of spatially resolved VEELS performed in scanning transmission mode and the alignments necessary to achieve the current optimum performance of approximately 0.15 eV energy resolution with an electron probe size of approximately 1 nm. In particular, a collection of basic concepts concerning the acquisition process, the optimization of the energy resolution, the spatial resolution and the data processing are provided. A brief study of planar defects in a Y(1)Ba(2)Cu(3)O(7-)(delta) high-temperature superconductor illustrates these concepts and shows what kind of information can be accessed by VEELS.

  20. An Auger Sputter Profiling Study of Nitrogen and Oxygen Ion Implantations in Two Titanium Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Barton, B. D., Pope, L. E., Wittberg, T. N.

    1989-07-31

    Samples of two titanium alloys, Ti-6A1-4V and Ti-15V-3Cr-3Sn-3A1, were ion implanted with a combination of nitrogen (N+) and oxygen (O+). For each alloy, implantation parameters were chosen to give implanted nitrogen concentrations of approximately 10 or 50 atomic percent, from a depth of 100 nanometers to a depth of 400 nanometers. In all but one case, dual energy (200 keV and 90 keV) implantations of nitrogen were used to give a relatively uniform nitrogen concentration to a depth of 300 nanometers. In each case, oxygen was implanted at 35 keV, following the nitrogen implantation, to give an oxygen-enriched region near the surface. The implanted samples were then examined by Auger electron spectroscopy (AES) combined with argon ion sputtering. In order to determine the stoichiometry of the nitrogen implanted regions, it was necessary to determine the N (KVV) contribution to the overlapping N (KVV) and Ti (LMM) Auger transitions. It was also necessary to correct for the ion-bombardment-induced compositional changes which have been described in an earlier study of titanium nitride thin films. The corrected AES depth profiles were in good agreement with theoretical predictions.

  1. Compact design for two-dimensional electronic spectroscopy

    Science.gov (United States)

    Huang, Zheng; Wang, Peng; Shen, Xiong; Yan, Tian-Min; Zhang, Yizhu; Liu, Jun

    2016-03-01

    We present a passively phase-stabilized two-dimensional electronic spectroscopy (2DES) with a compact size, and the ease of implementation and maintenance. Our design relies on a mask beam-splitter with four holes to form non-collinear box geometry, and a homebuilt stacked retroreflector, which introduces the phase-locked pulse sequence, remedying the instability of commonly used translation stages. The minimized size of the setup suppresses the influences of optical path-length fluctuations during measurements, improving the phase stability and precise timing of pulse sequences. In our 2DES, only few conventional optical components are used, which make this sophisticated instrumentation convenient to establish and particularly easy to conduct alignment. In data analysis, the self-referencing spectral interferometry (SRSI) method is first introduced to extract the complex-valued signal from spectral interferometry in 2DES. The alternative algorithm achieves the improvement of the signal-to-noise ratio (SNR) and considerable reduction of data acquisition time. The new setup is suitable over a tunable range of spectroscopic wavelength, from ultraviolet (UV) to the near-infrared (NIR) regime, and for ultra-broadband bandwidth, few-cycle laser pulses.

  2. Experimental KLM + KLN Auger spectrum of Cu

    Energy Technology Data Exchange (ETDEWEB)

    Inoyatov, A.Kh., E-mail: inoyatov@jinr.ru [Laboratory of Nuclear Problems, JINR, Dubna, Moscow Region (Russian Federation); Institute of Applied Physics, National University, Tashkent (Uzbekistan); Perevoshchikov, L.L. [Laboratory of Nuclear Problems, JINR, Dubna, Moscow Region (Russian Federation); Zhdanov, V.S. [Institute of Nuclear Physics, Almaty (Kazakhstan); Filosofov, D.V. [Laboratory of Nuclear Problems, JINR, Dubna, Moscow Region (Russian Federation); Kovalík, A. [Laboratory of Nuclear Problems, JINR, Dubna, Moscow Region (Russian Federation); Nuclear Physics Institute of the ASCR, Řež near Prague (Czech Republic)

    2013-08-15

    Highlights: •The KLM Auger spectrum of Cu was measured for the first time in detail. •Energies and relative intensities of nine resolved spectrum components were determined. •Semi-empirical KLM energy predictions and experiment agree mostly within 3σ with the exception of the transitions involving the M{sub 4,5} atomic subshells. •It was found that the KLM transition rates at Z = 29 should be calculated relativistically in intermediate coupling scheme. -- Abstract: The KLM + KLN Auger electron spectrum of Cu (Z = 29) emitted in the electron capture decay of radioactive {sup 65}Zn in a solid matrix was investigated for the first time using a combined electrostatic electron spectrometer adjusted to the 7 eV instrumental resolution. Energies and relative intensities of nine resolved spectrum components were determined and compared with theoretical expectations. An agreement within 3σ was found between the semi-empirical predictions for the KLM transition energies by Larkins and the experimental data with the exception of the weak (KL{sub 2}M{sub 4,5} + KL{sub 2}N{sub 1}) and (KL{sub 3}M{sub 4,5} + KL{sub 3}N{sub 1}) lines where the differences reached 5σ. From a comparison of the measured relative KLM transition intensities with available theoretical results a conclusion was derived that calculations of the KLM transition rates at Z = 29 should be based on intermediate coupling of angular momenta and take into account relativistic effects.

  3. Spectroscopy of hexafluorides with an odd number of electrons; Spectroscopie des hexafluorures a nombre impair d'electrons

    Energy Technology Data Exchange (ETDEWEB)

    Boudon, V

    1995-05-01

    From a theoretical point of view, a tensorial formalism adapted to the study of molecules or octahedral ions with a half-integer angular momentum has been developed for the first time. We have used here the method of projective representations, more consistent than that of double groups. A complete set of coupling coefficients and formulas, as well as the corresponding computing programs have been elaborated. This has firstly allowed us to write a simple model describing the vibronic structure of colored hexafluorides. Then, some applications of this formalism to the study of ro-vibronic couplings of XY{sub 6} molecules in a fourfold degenerate electronic state have been considered, especially concerning operators associated to dynamic Jahn-Teller effect. From an experimental point of view, we have considered IrF{sub 6}, for which we have mastered the synthesis, purification and conservation processes. A first study at low resolution (absorption and Raman scattering) has been performed for this molecule. We have then set up two high resolution spectroscopic devices in the visible region (saturated absorption - tested with an iodine cell- and simple absorption with multiple pass). These especially use a dye laser. They should now allow the spectroscopy of the visible band of IrF{sub 6} in order to resolve for the first time its fine rotational structure. (author)

  4. High-energy photoemission spectroscopy for investigating bulk electronic structures of strongly correlated systems

    Energy Technology Data Exchange (ETDEWEB)

    Sekiyama, Akira, E-mail: sekiyama@mp.es.osaka-u.ac.jp [Division of Materials Physics, Graduate School of Engineering Science, Osaka University, Toyonaka 560-8531, Osaka (Japan); SPring-8/RIKEN, Sayo 679-5148, Hyogo (Japan)

    2016-04-15

    Progress of high-energy photoemission spectroscopy for investigating the bulk electronic structures of strongly correlated electron systems is reviewed. High-resolution soft X-ray photoemission has opened the door for revealing the bulk strongly correlated spectral functions overcoming the surface contributions. More bulk-sensitive hard X-ray photoemission spectroscopy (HAXPES) enables us to study the electronic structure with negligible surface contribution. The recent development of the polarization-dependent HAXPES is also described in this short review.

  5. Suppression of auger recombination in ""giant"" core/shell nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Garcia Santamaria, Florencio [Los Alamos National Laboratory; Vela, Javier [Los Alamos National Laboratory; Schaller, Richard D [Los Alamos National Laboratory; Hollingsworth, Jennifer A [Los Alamos National Laboratory; Klimov, Victor I [Los Alamos National Laboratory; Chen, Yongfen [NON LANL

    2009-01-01

    Many potential applications of semiconductor nanocrystals are hindered by nonradiative Auger recombination wherein the electron-hole (exciton) recombination energy is transferred to a third charge carrier. This process severely limits the lifetime and bandwidth of optical gain, leads to large nonradiative losses in light emitting diodes and photovoltaic cells, and is believed to be responsible for intermittency ('blinking') of emission from single nanocrystals. The development of nanostructures in which Auger recombination is suppressed has been a longstanding goal in colloidal nanocrystal research. Here, we demonstrate that such suppression is possible using so-called 'giant' nanocrystals that consist of a small CdSe core and a thick CdS shell. These nanostructures exhibit a very long biexciton lifetime ({approx}10 ns) that is likely dominated by radiative decay instead of non-radiative Auger recombination. As a result of suppressed Auger recombination, even high-order multiexcitons exhibit high emission efficiencies, which allows us to demonstrate optical amplification with an extraordinarily large bandwidth (>500 me V) and record low excitation thresholds.

  6. Final state interaction observed in M{sub 2,3}VV Auger profile of Cu(110)

    Energy Technology Data Exchange (ETDEWEB)

    Nakajima, H; Songsiriritthigul, P [Synchrotron Light Research Institute, 111 University Avenue, Muang District, Nakhon Ratchasima 30000 (Thailand); Buddhakala, M [Department of Physics, Faculty of Science and Technology, Rajamangala University of Technology Thanyaburi, 39 Muh 1, Rangsit-Nakhonnayok Road Klong Hok, Thanyaburi District, Pathumthani 12110 (Thailand); Chumpolkulwong, S [Department of Physics, Faculty of Science, Udon Thani Rajabhat University, 64 Thahan Road, Muang District, Udon Thani 41000 (Thailand); Kakizaki, A [Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581 (Japan)], E-mail: hiden@nsrc.or.th

    2009-02-04

    We have measured the M{sub 2,3}VV Auger spectra of Cu(110) and studied the final state interaction following the Cu 3p core electron excitation. We have observed that the kinetic energy of the M{sub 2,3}VV Auger electron shifts to an energy higher than that of the normal Auger electrons near the Cu 3p threshold, and it converges to the constant kinetic energy of the normal Auger electrons as the excitation energy increases above the Cu 3p threshold. In the excitation energy dependence of the kinetic energies of the M{sub 2,3}VV Auger electrons, we observed step features at the excitation energies corresponding to the 3p core electron excitations to the L{sub 1} and X{sub 1} van Hove singularities in the valence states. The kinetic energy shifts of the M{sub 2,3}VV Auger electrons are reasonably understood by considering the localization of the two-hole Auger final state and the hybridization between Cu 3d states and other valence states.

  7. Electronic structure of layered titanate Nd2Ti2O7

    DEFF Research Database (Denmark)

    Atuchin, V.V.; Gavrilova, T.A.; Grivel, Jean-Claude

    2008-01-01

    The electronic structure of the binary titanate Nd2Ti2O7 has been studied by X-ray photoelectron spectroscopy (XPS). Spectral features of the valence band and all constituent element core levels have been considered. The Auger parameters of titanium and oxygen in Nd2Ti2O7 are determined as alpha...

  8. Electronic structure of layered ferroelectric high-k titanate La2Ti2O7

    DEFF Research Database (Denmark)

    Atuchin, V. V.; Gavrilova, T. A.; Grivel, Jean-Claude

    2009-01-01

    The electronic structure of binary titanate La2Ti2O7 has been studied by x-ray photoelectron spectroscopy. Spectral features of valence band and all constituent element core levels have been considered. The Auger parameters of titanium and oxygen in La2Ti2O7 are determined as alpha(Ti) = 872...

  9. Single, double, and triple Auger decays from 1s shake-up states of the oxygen molecule

    Science.gov (United States)

    Kaneyasu, T.; Odagiri, T.; Nakagawa, M.; Mashiko, R.; Tanaka, H.; Adachi, J.; Hikosaka, Y.

    2017-09-01

    The single, double, and triple Auger decays from the 1s shake-up states of O2 have been studied using a multi-electron coincidence method. Efficient populations of two-hole final states are observed in single Auger decays of the π-π* shake-up states, which is understood as a characteristic property of the Auger transitions from shake-up states of an open-shell molecule. The O23+ populations formed by double Auger decays show similar profiles for both the O1s-1 and shake-up states, which is due to the contributions from cascade double Auger processes. While the cascade contributions to the double Auger decays increase with the initial shake-up energy, the probability of direct double Auger processes remains unchanged between the O1s-1 and shake-up states, which implies a weak influence of the excited electron on the double Auger emission that originates from the electron correlation effect.

  10. Effect of Auger Recombination on Lasing in Heterostructured Quantum Dots with Engineered Core/Shell Interfaces.

    Science.gov (United States)

    Park, Young-Shin; Bae, Wan Ki; Baker, Thomas; Lim, Jaehoon; Klimov, Victor I

    2015-11-11

    Nanocrystal quantum dots (QDs) are attractive materials for applications as laser media because of their bright, size-tunable emission and the flexibility afforded by colloidal synthesis. Nonradiative Auger recombination, however, hampers optical amplification in QDs by rapidly depleting the population of gain-active multiexciton states. In order to elucidate the role of Auger recombination in QD lasing and isolate its influence from other factors that might affect optical gain, we study two types of CdSe/CdS core/shell QDs with the same core radii and the same total sizes but different properties of the core/shell interface ("sharp" vs "smooth"). These samples exhibit distinctly different biexciton Auger lifetimes but are otherwise virtually identical. The suppression of Auger recombination in the sample with a smooth (alloyed) interface results in a notable improvement in the optical gain performance manifested in the reduction of the threshold for amplified spontaneous emission and the ability to produce dual-color lasing involving both the band-edge (1S) and the higher-energy (1P) electronic states. We develop a model, which explicitly accounts for the multiexciton nature of optical gain in QDs, and use it to analyze the competition between stimulated emission from multiexcitons and their decay via Auger recombination. These studies re-emphasize the importance of Auger recombination control for the realization of real-life QD-based lasing technologies and offer practical strategies for suppression of Auger recombination via "interface engineering" in core/shell structures.

  11. Symmetry-broken effects on electron momentum spectroscopy caused by adiabatic vibration

    Science.gov (United States)

    Zhu, Yinghao; Ma, Xiaoguang; Lou, Wenhua; Wang, Meishan; Yang, Chuanlu

    2017-11-01

    The vibronic coupling effect is usually studied by invoking the breakdown of Born-Oppenheimer approximation. The present study shows that the symmetry-broken effect induced by nuclei vibrations can also lead strong impact on the electronic states under the framework of Born-Oppenheimer approximation. This adiabatic-invoking vibrational effect on electron momentum spectroscopy of ethylene (C2H4), ethane (C2H6) and methanol (CH3OH) was studied with quantum mechanical method. The results show that electron momentum spectroscopy of localized electrons, especially core electrons in axial symmetric geometry molecules can be affected unusually and strongly by several asymmetric vibrational modes.

  12. Modeling the high-energy electronic state manifold of adenine: Calibration for nonlinear electronic spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Nenov, Artur, E-mail: Artur.Nenov@unibo.it; Giussani, Angelo; Segarra-Martí, Javier; Jaiswal, Vishal K. [Dipartimento di Chimica “G. Ciamician,” Università di Bologna, Via Selmi 2, IT-40126 Bologna (Italy); Rivalta, Ivan [Université de Lyon, CNRS, Institut de Chimie de Lyon, École Normale Supérieure de Lyon, 46 Allée d’Italie, F-69364 Lyon Cedex 07 (France); Cerullo, Giulio [Dipartimento di Fisica, Politecnico di Milano, IFN-CNR, Piazza Leonardo Da Vinci 32, IT-20133 Milano (Italy); Mukamel, Shaul [Department of Chemistry, University of California, Irvine, California 92697-2025 (United States); Garavelli, Marco, E-mail: marco.garavelli@unibo.it, E-mail: marco.garavelli@ens-lyon.fr [Dipartimento di Chimica “G. Ciamician,” Università di Bologna, Via Selmi 2, IT-40126 Bologna (Italy); Université de Lyon, CNRS, Institut de Chimie de Lyon, École Normale Supérieure de Lyon, 46 Allée d’Italie, F-69364 Lyon Cedex 07 (France)

    2015-06-07

    Pump-probe electronic spectroscopy using femtosecond laser pulses has evolved into a standard tool for tracking ultrafast excited state dynamics. Its two-dimensional (2D) counterpart is becoming an increasingly available and promising technique for resolving many of the limitations of pump-probe caused by spectral congestion. The ability to simulate pump-probe and 2D spectra from ab initio computations would allow one to link mechanistic observables like molecular motions and the making/breaking of chemical bonds to experimental observables like excited state lifetimes and quantum yields. From a theoretical standpoint, the characterization of the electronic transitions in the visible (Vis)/ultraviolet (UV), which are excited via the interaction of a molecular system with the incoming pump/probe pulses, translates into the determination of a computationally challenging number of excited states (going over 100) even for small/medium sized systems. A protocol is therefore required to evaluate the fluctuations of spectral properties like transition energies and dipole moments as a function of the computational parameters and to estimate the effect of these fluctuations on the transient spectral appearance. In the present contribution such a protocol is presented within the framework of complete and restricted active space self-consistent field theory and its second-order perturbation theory extensions. The electronic excited states of adenine have been carefully characterized through a previously presented computational recipe [Nenov et al., Comput. Theor. Chem. 1040–1041, 295-303 (2014)]. A wise reduction of the level of theory has then been performed in order to obtain a computationally less demanding approach that is still able to reproduce the characteristic features of the reference data. Foreseeing the potentiality of 2D electronic spectroscopy to track polynucleotide ground and excited state dynamics, and in particular its expected ability to provide

  13. Electronic excitation of furfural as probed by high-resolution vacuum ultraviolet spectroscopy, electron energy loss spectroscopy, and ab initio calculations

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira da Silva, F.; Lange, E. [Laboratório de Colisões Atómicas e Moleculares, CEFITEC, Departamento de Física, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Limão-Vieira, P., E-mail: plimaovieira@fct.unl.pt, E-mail: michael.brunger@flinders.edu.au, E-mail: maplima@ifi.unicamp.br [Laboratório de Colisões Atómicas e Moleculares, CEFITEC, Departamento de Física, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, South Australia 5001 (Australia); Jones, N. C.; Hoffmann, S. V. [ISA, Department of Physics and Astronomy, Aarhus University, Ny Munkegade, DK-8000 Århus C (Denmark); Hubin-Franskin, M.-J.; Delwiche, J. [Départment de Chimie, Institut de Chimie-Bât. B6C, Université de Liège, B-4000 Liège 1 (Belgium); Brunger, M. J., E-mail: plimaovieira@fct.unl.pt, E-mail: michael.brunger@flinders.edu.au, E-mail: maplima@ifi.unicamp.br [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, South Australia 5001 (Australia); Institute of Mathematical Sciences, University of Malaya, 50603 Kuala Lumpur (Malaysia); and others

    2015-10-14

    The electronic spectroscopy of isolated furfural (2-furaldehyde) in the gas phase has been investigated using high-resolution photoabsorption spectroscopy in the 3.5–10.8 eV energy-range, with absolute cross section measurements derived. Electron energy loss spectra are also measured over a range of kinematical conditions. Those energy loss spectra are used to derive differential cross sections and in turn generalised oscillator strengths. These experiments are supported by ab initio calculations in order to assign the excited states of the neutral molecule. The good agreement between the theoretical results and the measurements allows us to provide the first quantitative assignment of the electronic state spectroscopy of furfural over an extended energy range.

  14. Electronic properties of Mn-phthalocyanine–C{sub 60} bulk heterojunctions: Combining photoemission and electron energy-loss spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Roth, Friedrich [Center for Free-Electron Laser Science/DESY, Notkestraße 85, D-22607 Hamburg (Germany); Herzig, Melanie; Knupfer, Martin [FW Dresden, P.O. Box 270116, D-01171 Dresden (Germany); Lupulescu, Cosmin [Institute of Optics and Atomic Physics, TU Berlin, Straße des 17. Juni 135, D-10623 Berlin (Germany); Darlatt, Erik; Gottwald, Alexander [Physikalisch-Technische Bundesanstalt (PTB), Abbestraße 2-12, D-10587 Berlin (Germany); Eberhardt, Wolfgang [Center for Free-Electron Laser Science/DESY, Notkestraße 85, D-22607 Hamburg (Germany); Institute of Optics and Atomic Physics, TU Berlin, Straße des 17. Juni 135, D-10623 Berlin (Germany)

    2015-11-14

    The electronic properties of co-evaporated mixtures (blends) of manganese phthalocyanine and the fullerene C{sub 60} (MnPc:C{sub 60}) have been studied as a function of the concentration of the two constituents using two supplementary electron spectroscopic methods, photoemission spectroscopy (PES) and electron energy-loss spectroscopy (EELS) in transmission. Our PES measurements provide a detailed picture of the electronic structure measured with different excitation energies as well as different mixing ratios between MnPc and C{sub 60}. Besides a relative energy shift, the occupied electronic states of the two materials remain essentially unchanged. The observed energy level alignment is different compared to that of the related CuPc:C{sub 60} bulk heterojunction. Moreover, the results from our EELS investigations show that, despite the rather small interface interaction, the MnPc related electronic excitation spectrum changes significantly by admixing C{sub 60} to MnPc thin films.

  15. Angle-Resolved Photoemission Spectroscopy on Electronic Structure and Electron-Phonon Coupling in Cuprate Superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, X.J.

    2010-04-30

    In addition to the record high superconducting transition temperature (T{sub c}), high temperature cuprate superconductors are characterized by their unusual superconducting properties below T{sub c}, and anomalous normal state properties above T{sub c}. In the superconducting state, although it has long been realized that superconductivity still involves Cooper pairs, as in the traditional BCS theory, the experimentally determined d-wave pairing is different from the usual s-wave pairing found in conventional superconductors. The identification of the pairing mechanism in cuprate superconductors remains an outstanding issue. The normal state properties, particularly in the underdoped region, have been found to be at odd with conventional metals which is usually described by Fermi liquid theory; instead, the normal state at optimal doping fits better with the marginal Fermi liquid phenomenology. Most notable is the observation of the pseudogap state in the underdoped region above T{sub c}. As in other strongly correlated electrons systems, these unusual properties stem from the interplay between electronic, magnetic, lattice and orbital degrees of freedom. Understanding the microscopic process involved in these materials and the interaction of electrons with other entities is essential to understand the mechanism of high temperature superconductivity. Since the discovery of high-T{sub c} superconductivity in cuprates, angle-resolved photoemission spectroscopy (ARPES) has provided key experimental insights in revealing the electronic structure of high temperature superconductors. These include, among others, the earliest identification of dispersion and a large Fermi surface, an anisotropic superconducting gap suggestive of a d-wave order parameter, and an observation of the pseudogap in underdoped samples. In the mean time, this technique itself has experienced a dramatic improvement in its energy and momentum resolutions, leading to a series of new discoveries not

  16. Scanning electron microscopy and X-ray spectroscopy applied to mycelial phase of sporothrix schenckii

    Directory of Open Access Journals (Sweden)

    M. Thibaut

    1975-04-01

    Full Text Available Scanning electron microscopy applied to the mycelial phase of Sporothrix schenckii shows a matted mycelium with conidia of a regular pattern. X-Ray microanalysis applied in energy dispersive spectroscopy and also in wavelength dispersive spectroscopy reveals the presence of several elements of Mendeleef's classification.

  17. Autoionization of Be-like ions following double electron capture in C sup 4+ , O sup 6+ and Ne sup 8+ ions

    Energy Technology Data Exchange (ETDEWEB)

    McDonald, J.W.

    1990-09-11

    This paper describes electron emission following the autoionization of doubly excited states in Be-like ions. The Be-like Auger states are produced by two electron capture in slow C{sup 4+}, O{sup 6+} and Ne{sup 8+} ions. These measurements were performed by means of high resolution Auger electron spectroscopy on different target gases and at different projectile energies. Line assignments and relative cross sections are given for the investigated doubly excited states and the excitation mechanism is discussed. 15 refs., 16 figs., 4 tabs.

  18. Electron energy loss spectroscopy (EELS) of organic molecules in ...

    Indian Academy of Sciences (India)

    India. Abstract. An indigenous electron energy loss spectrometer has been designed and fabricated for the study of free molecules. The spectrometer enables the recording of - low-resolution electronic spectra of molecules in the vapour phase with ready access to the vacuum ultraviolet region. Electron energy loss spectra ...

  19. Electronic structure investigation of oxidized aluminium films with electron momentum spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Guo, X.; Canney, S.; Kheifets, A.S.; Vos, M.; Fang, Z.; Utteridge, S.; McCarthy, I.E. [Flinders Univ. of South Australia, Adelaide, SA (Australia). Electronic Structure of Materials Centre; Weigold, E. [Australian National Univ., Canberra, ACT (Australia). Research School of Physical Sciences

    1996-09-01

    Electron momentum spectroscopy (EMS) of (e, 2e) measurements with oxidized aluminium thin films have been performed. Due to the surface sensitive mature of the EMS spectrometer employed the measured (e, 2e) events come from the front oxidized layer as viewed by the electron detectors. The measurements show clearly two major features in the spectral momentum density distribution and they are related to the upper valence band and the lower valence band of aluminum oxide. The first is a `dual parabola` energy-momentum dispersion pattern spanning about 8 eV in the upper valence band. This `dual parabola` pattern has been qualitatively reproduced by a linear muffin-tin orbital (LMTO) calculation on spherically averaged {alpha}-A1{sub 2}O{sub 3} with nearly the same energy span. In the lower valence band, the LMTO calculation indicates a dispersion spanning about 5 eV, and the measured spectral momentum density plot shows a similar `bowl` shape but with less dispersion. The possible causes which blur the dispersion in the lower valence band are discussed. Other features in the spectral momentum density distribution are also discussed and compared with the LMTO calculation. 45 refs., 1 tab., 10 figs.

  20. Auger yield calculations for medical radioisotopes

    Directory of Open Access Journals (Sweden)

    Lee Boon Q.

    2015-01-01

    Full Text Available Auger yields from the decays of 71Ge, 99mTc, 111In and 123–125I have been calculated using a Monte Carlo model of the Auger cascade that has been developed at the ANU. In addition, progress to improve the input data of the model has been made with the Multiconfiguration Dirac-Hartree-Fock method.

  1. Time- and angle-resolved photoemission spectroscopy of hydrated electrons near a liquid water surface.

    Science.gov (United States)

    Yamamoto, Yo-ichi; Suzuki, Yoshi-Ichi; Tomasello, Gaia; Horio, Takuya; Karashima, Shutaro; Mitríc, Roland; Suzuki, Toshinori

    2014-05-09

    We present time- and angle-resolved photoemission spectroscopy of trapped electrons near liquid surfaces. Photoemission from the ground state of a hydrated electron at 260 nm is found to be isotropic, while anisotropic photoemission is observed for the excited states of 1,4-diazabicyclo[2,2,2]octane and I- in aqueous solutions. Our results indicate that surface and subsurface species create hydrated electrons in the bulk side. No signature of a surface-bound electron has been observed.

  2. Practical guide to surface science and spectroscopy

    CERN Document Server

    Chung, Yip-Wah

    2001-01-01

    Practical Guide to Surface Science and Spectroscopy provides a practical introduction to surface science as well as describes the basic analytical techniques that researchers use to understand what occurs at the surfaces of materials and at their interfaces. These techniques include auger electron spectroscopy, photoelectron spectroscopy, inelastic scattering of electrons and ions, low energy electron diffraction, scanning probe microscopy, and interfacial segregation. Understanding the behavior of materials at their surfaces is essential for materials scientists and engineers as they design and fabricate microelectronics and semiconductor devices. The book gives over 100 examples, discussion questions and problems with varying levels of difficulty. Included with this book is a CD-ROM, which not only contains the same information, but also provides many elements of animation and interaction that are not easily emulated on paper. In diverse subject matters ranging from the operation of ion pumps, computer-...

  3. FEMTOSECOND SPECTROSCOPY OF SOLVATED ELECTRON IN AQUEOUS MEDIA

    OpenAIRE

    Gauduel, Yann; Pommeret, S.; Antonetti, A.

    1991-01-01

    The elucidation of detailed mechanisms of ultrafast events that occur in molecular charge transfer or reaction dynamics has been made possible by recent advances in spectroscopy techniques that use ultrashort laser pulse generation. Ultrashort laser pulses (100 femtoseconds duration, 1 fs = 10-15 s) allow to initiate selective photochemical processes (single charge transfer for instance) and to obtain unique informations on the dynamics of primary steps of radical reactions involving ultrafas...

  4. Direct rate assessment of laccase catalysed radical formation in lignin by electron paramagnetic resonance spectroscopy

    DEFF Research Database (Denmark)

    Munk, Line; Andersen, Mogens Larsen; Meyer, Anne S.

    2017-01-01

    Laccases (EC 1.10.3.2) catalyse removal of an electron and a proton from phenolic hydroxyl groups, including phenolic hydroxyls in lignins, to form phenoxy radicals during reduction of O2. We employed electron paramagnetic resonance spectroscopy (EPR) for real time measurement of such catalytic...

  5. High field electron paramagnetic resonance spectroscopy under ultrahigh vacuum conditions—A multipurpose machine to study paramagnetic species on well defined single crystal surfaces

    Science.gov (United States)

    Rocker, J.; Cornu, D.; Kieseritzky, E.; Seiler, A.; Bondarchuk, O.; Hänsel-Ziegler, W.; Risse, T.; Freund, H.-J.

    2014-08-01

    A new ultrahigh vacuum (UHV) electron paramagnetic resonance (EPR) spectrometer operating at 94 GHz to investigate paramagnetic centers on single crystal surfaces is described. It is particularly designed to study paramagnetic centers on well-defined model catalysts using epitaxial thin oxide films grown on metal single crystals. The EPR setup is based on a commercial Bruker E600 spectrometer, which is adapted to ultrahigh vacuum conditions using a home made Fabry Perot resonator. The key idea of the resonator is to use the planar metal single crystal required to grow the single crystalline oxide films as one of the mirrors of the resonator. EPR spectroscopy is solely sensitive to paramagnetic species, which are typically minority species in such a system. Hence, additional experimental characterization tools are required to allow for a comprehensive investigation of the surface. The apparatus includes a preparation chamber hosting equipment, which is required to prepare supported model catalysts. In addition, surface characterization tools such as low energy electron diffraction (LEED)/Auger spectroscopy, temperature programmed desorption (TPD), and infrared reflection absorption spectroscopy (IRAS) are available to characterize the surfaces. A second chamber used to perform EPR spectroscopy at 94 GHz has a room temperature scanning tunneling microscope attached to it, which allows for real space structural characterization. The heart of the UHV adaptation of the EPR experiment is the sealing of the Fabry-Perot resonator against atmosphere. To this end it is possible to use a thin sapphire window glued to the backside of the coupling orifice of the Fabry Perot resonator. With the help of a variety of stabilization measures reducing vibrations as well as thermal drift it is possible to accumulate data for a time span, which is for low temperature measurements only limited by the amount of liquid helium. Test measurements show that the system can detect paramagnetic

  6. High field electron paramagnetic resonance spectroscopy under ultrahigh vacuum conditions—A multipurpose machine to study paramagnetic species on well defined single crystal surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Rocker, J.; Cornu, D.; Kieseritzky, E.; Hänsel-Ziegler, W.; Freund, H.-J. [Fritz-Haber-Institut der MPG, Faradayweg 4-6, 14195 Berlin (Germany); Seiler, A. [Fritz-Haber-Institut der MPG, Faradayweg 4-6, 14195 Berlin (Germany); Laboratorium für Applikationen der Synchrotronstrahlung, KIT Campus Süd, Kaiserstr. 12, 76131 Karlsruhe (Germany); Bondarchuk, O. [Fritz-Haber-Institut der MPG, Faradayweg 4-6, 14195 Berlin (Germany); CIC energiGUNE, Parque Tecnologico, C/Albert Einstein 48, CP 01510 Minano (Alava) (Spain); Risse, T., E-mail: risse@chemie.fu-berlin.de [Fritz-Haber-Institut der MPG, Faradayweg 4-6, 14195 Berlin (Germany); Institut für Chemie und Biochemie, Freie Universität Berlin, Takustr. 3, 14195 Berlin (Germany)

    2014-08-01

    A new ultrahigh vacuum (UHV) electron paramagnetic resonance (EPR) spectrometer operating at 94 GHz to investigate paramagnetic centers on single crystal surfaces is described. It is particularly designed to study paramagnetic centers on well-defined model catalysts using epitaxial thin oxide films grown on metal single crystals. The EPR setup is based on a commercial Bruker E600 spectrometer, which is adapted to ultrahigh vacuum conditions using a home made Fabry Perot resonator. The key idea of the resonator is to use the planar metal single crystal required to grow the single crystalline oxide films as one of the mirrors of the resonator. EPR spectroscopy is solely sensitive to paramagnetic species, which are typically minority species in such a system. Hence, additional experimental characterization tools are required to allow for a comprehensive investigation of the surface. The apparatus includes a preparation chamber hosting equipment, which is required to prepare supported model catalysts. In addition, surface characterization tools such as low energy electron diffraction (LEED)/Auger spectroscopy, temperature programmed desorption (TPD), and infrared reflection absorption spectroscopy (IRAS) are available to characterize the surfaces. A second chamber used to perform EPR spectroscopy at 94 GHz has a room temperature scanning tunneling microscope attached to it, which allows for real space structural characterization. The heart of the UHV adaptation of the EPR experiment is the sealing of the Fabry-Perot resonator against atmosphere. To this end it is possible to use a thin sapphire window glued to the backside of the coupling orifice of the Fabry Perot resonator. With the help of a variety of stabilization measures reducing vibrations as well as thermal drift it is possible to accumulate data for a time span, which is for low temperature measurements only limited by the amount of liquid helium. Test measurements show that the system can detect paramagnetic

  7. Electron-Induced Vibrational Spectroscopy. A New and Unique Tool To Unravel the Molecular Structure of Polymer Surfaces

    NARCIS (Netherlands)

    Pireaux, J.J.; Gregoire, Ch.; Caudano, R.; Rei Vilar, M.; Brinkhuis, R.; Schouten, A.J.

    1991-01-01

    Among the surface-sensitive spectroscopies used to characterize clean and surface-modified polymers, one technique has rather recently emerged as a very promising complementary tool. High-resolution electron energy loss spectroscopy, or electron-induced vibrational spectroscopy, has potentially all

  8. Universal size dependence of auger constants in direct- and indirect-gap semiconductor nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Robel, Istvan [Los Alamos National Laboratory; Schaller, Richard D [Los Alamos National Laboratory; Klimov, Victor I [Los Alamos National Laboratory; Gresback, Ryan [U OF MINNESOTA; Kortshagen, Uwe [U OF MINNESOTA

    2008-01-01

    Three-dimensional (3D) spatial confinement of electronic wave functions in semiconductor nanocrystals (NCs) results in a significant enhancement of multi-electron phenomena including non radiative Auger recombination. In this process, a conduction-band electron recombines with a valence-band hole by transferring the recombination energy to a third carrier. Significant interest in Auger recombination in NCs has been stimulated by recent studies ofNC lasing, and generation-III photovoltaics enabled by carrier multiplication because in both of these prospective applications Auger recombination represents a dominant carrier-loss mechanism. Here, we perform a side-by-side comparison of Auger recombination rates in NCs of several different compositions including Ge, PbSe, InAs, and CdSe. We observe that the only factor, which has a significant effect on the measured recombination rates, is the size of the NCs but not the details of the material's electronic structure. Most surprisingly, comparable rates are measured for nanocrystals of directand indirect-gap semiconductor NCs despite a dramatic four-to-five orders of magnitude difference in respective bulk-semiconductor Auger constants. This unusual observation can be explained by confinement-induced relaxation of momentum conservation, which smears out the difference between direct- and indirect-gap materials.

  9. High energy photoelectron spectroscopy in basic and applied science: Bulk and interface electronic structure

    Energy Technology Data Exchange (ETDEWEB)

    Knut, Ronny; Lindblad, Rebecka [Department of Physics and Astronomy, Uppsala University, SE-751 21 Uppsala (Sweden); Gorgoi, Mihaela [Helmholtz Zentrum Berlin für Materialien und Energie GmbH, Albert-Einstein-Str. 15, 12489 Berlin (Germany); Rensmo, Håkan [Department of Physics and Astronomy, Uppsala University, SE-751 21 Uppsala (Sweden); Karis, Olof, E-mail: olof.karis@physics.uu.se [Department of Physics and Astronomy, Uppsala University, SE-751 21 Uppsala (Sweden)

    2013-10-15

    Highlights: •We demonstrate how hard X-ray photoelectron spectroscopy can be used to investigate interface properties of multilayers. •By combining HAXPES and statistical methods we are able to provide quantitative analysis of the interface diffusion process. •We show how photoionization cross sections can be used to map partial density of states contributions to valence states. •We use HAXPES to provide insight into the valence electronic structure of e.g. multiferroics and dye-sensitized solar cells. -- Abstract: With the access of new high-performance electron spectrometers capable of analyzing electron energies up to the order of 10 keV, the interest for photoelectron spectroscopy has grown and many new applications of the technique in areas where electron spectroscopies were considered to have limited use have been demonstrated over the last few decades. The technique, often denoted hard X-ray photoelectron spectroscopy (HX-PES or HAXPES), to distinguish the experiment from X-ray photoelectron spectroscopy performed at lower energies, has resulted in an increasing interest in photoelectron spectroscopy in many areas. The much increased mean free path at higher kinetic energies, in combination with the elemental selectivity of the core level spectroscopies in general has led to this fact. It is thus now possible to investigate the electronic structure of materials with a substantially enhanced bulk sensitivity. In this review we provide examples from our own research using HAXPES which to date has been performed mainly at the HIKE facility at the KMC-1 beamline at HZB, Berlin. The review exemplifies the new opportunities using HAXPES to address both bulk and interface electronic properties in systems relevant for applications in magnetic storage, energy related research, but also in purely curiosity driven problems.

  10. Resolving molecular vibronic structure using high-sensitivity two-dimensional electronic spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Bizimana, Laurie A.; Brazard, Johanna; Carbery, William P.; Gellen, Tobias; Turner, Daniel B., E-mail: dturner@nyu.edu [Department of Chemistry, New York University, 100 Washington Square East, New York, New York 10003 (United States)

    2015-10-28

    Coherent multidimensional optical spectroscopy is an emerging technique for resolving structure and ultrafast dynamics of molecules, proteins, semiconductors, and other materials. A current challenge is the quality of kinetics that are examined as a function of waiting time. Inspired by noise-suppression methods of transient absorption, here we incorporate shot-by-shot acquisitions and balanced detection into coherent multidimensional optical spectroscopy. We demonstrate that implementing noise-suppression methods in two-dimensional electronic spectroscopy not only improves the quality of features in individual spectra but also increases the sensitivity to ultrafast time-dependent changes in the spectral features. Measurements on cresyl violet perchlorate are consistent with the vibronic pattern predicted by theoretical models of a highly displaced harmonic oscillator. The noise-suppression methods should benefit research into coherent electronic dynamics, and they can be adapted to multidimensional spectroscopies across the infrared and ultraviolet frequency ranges.

  11. Resolving molecular vibronic structure using high-sensitivity two-dimensional electronic spectroscopy.

    Science.gov (United States)

    Bizimana, Laurie A; Brazard, Johanna; Carbery, William P; Gellen, Tobias; Turner, Daniel B

    2015-10-28

    Coherent multidimensional optical spectroscopy is an emerging technique for resolving structure and ultrafast dynamics of molecules, proteins, semiconductors, and other materials. A current challenge is the quality of kinetics that are examined as a function of waiting time. Inspired by noise-suppression methods of transient absorption, here we incorporate shot-by-shot acquisitions and balanced detection into coherent multidimensional optical spectroscopy. We demonstrate that implementing noise-suppression methods in two-dimensional electronic spectroscopy not only improves the quality of features in individual spectra but also increases the sensitivity to ultrafast time-dependent changes in the spectral features. Measurements on cresyl violet perchlorate are consistent with the vibronic pattern predicted by theoretical models of a highly displaced harmonic oscillator. The noise-suppression methods should benefit research into coherent electronic dynamics, and they can be adapted to multidimensional spectroscopies across the infrared and ultraviolet frequency ranges.

  12. Electron beam imaging and spectroscopy of plasmonic nanoantenna resonances

    NARCIS (Netherlands)

    Vesseur, P.C.

    2011-01-01

    Nanoantennas are metal structures that provide strong optical coupling between a nanoscale volume and the far field. This coupling is mediated by surface plasmons, oscillations of the free electrons in the metal. Increasing the control over the resonant plasmonic field distribution opens up a wide

  13. A study of electron scattering through noise spectroscopy

    NARCIS (Netherlands)

    Kumar, Manohar

    2012-01-01

    Charge counting statistics (C.S.) of traversing electron in quantum devices like atomic-molecular junctions is sensitive to the local perturbation in the charge field at the contact and in the quantum channels. The first cumulant of C.S. i.e. current-voltage characteristic of such devices has been

  14. Atmospheric Corrosion on Steel Studied by Conversion Electron Moessbauer Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Nakanishi, Akio; Kobayashi, Takayuki [Shiga University of Medical Science, Department of Physics (Japan)

    2004-12-15

    In order to investigate initial products on steel by atmospheric corrosion, conversion electron Moessbauer measurements were carried out at temperatures between 15 K and room temperature. From the results obtained at low temperatures, it was found that the corrosion products on steel consisted of ferrihydrite.

  15. Gas Phase Molecular Spectroscopy: Electronic Spectroscopy of Combustion Intermediates, Chlorine Azide kinetics, and Rovibrational Energy Transfer in Acetylene

    Science.gov (United States)

    Freel, Keith A.

    This dissertation is composed of three sections. The first deals with the electronic spectroscopy of combustion intermediates that are related to the formation of polycyclic aromatic hydrocarbons. Absorption spectra for phenyl, phenoxy, benzyl, and phenyl peroxy radicals were recorded using the technique of cavity ring-down spectroscopy. When possible, molecular constants, vibrational frequencies, and excited state lifetimes for these radicals were derived from these data. The results were supported by theoretical predictions. The second section presents a study of electron attachment to chlorine azide (ClN3) using a flowing-afterglow Langmuir-probe apparatus. Electron attachment rates were measured to be 3.5x10-8 and 4.5x10-8 cm3s-1 at 298 and 400 K respectively. The reactions of ClN3 with eighteen cations and seventeen anions were characterized. Rate constants were measured using a selected ion flow tube. The ionization energy (>9.6eV), proton affinity (713+/-41 kJ mol-1), and electron affinity (2.48+/-0.2 eV) for ClN 3 were determined from these data. The third section demonstrates the use of double resonance spectroscopy to observe state-selected rovibrational energy transfer from the first overtone asymmetric stretch of acetylene. The total population removal rate constants from various rotational levels of the (1,0,1,00,00) vibrational state were determined to be in the range of (9-17) x 10 -10 cm3s-1. Rotational energy transfer accounted for approximately 90% of the total removal rate from each state. Therefore, the upper limit of vibrational energy transfer from the (1,0,1,0 0,00) state was 10%.

  16. Damage-free vibrational spectroscopy of biological materials in the electron microscope.

    Science.gov (United States)

    Rez, Peter; Aoki, Toshihiro; March, Katia; Gur, Dvir; Krivanek, Ondrej L; Dellby, Niklas; Lovejoy, Tracy C; Wolf, Sharon G; Cohen, Hagai

    2016-03-10

    Vibrational spectroscopy in the electron microscope would be transformative in the study of biological samples, provided that radiation damage could be prevented. However, electron beams typically create high-energy excitations that severely accelerate sample degradation. Here this major difficulty is overcome using an 'aloof' electron beam, positioned tens of nanometres away from the sample: high-energy excitations are suppressed, while vibrational modes of energies <1 eV can be 'safely' investigated. To demonstrate the potential of aloof spectroscopy, we record electron energy loss spectra from biogenic guanine crystals in their native state, resolving their characteristic C-H, N-H and C=O vibrational signatures with no observable radiation damage. The technique opens up the possibility of non-damaging compositional analyses of organic functional groups, including non-crystalline biological materials, at a spatial resolution of ∼10 nm, simultaneously combined with imaging in the electron microscope.

  17. Probing Plasmonic Nanostructures with Electron Energy - Loss Spectroscopy

    DEFF Research Database (Denmark)

    Raza, Søren

    -response approximation. Irrespective of the microscopic origin, we find that nonlocal response modifies the electromagnetic wave equation by an additional Laplacian term. The hydrodynamic model, which includes nonlocal response through the Thomas–Fermi pressure of a free-electron gas, is discussed. We present also...... the generalized nonlocal optical response model, which expands the hydrodynamic model by taking into account the diffusion of free electrons in metals through Fick’s law. We go on to consider the implications of these two nonlocal models in the following plasmonic geometries: metal-insulator interface, nanosphere....... Above the plasma frequency, resonant excitations are supported by nonlocal theory due to the inclusion of curl-free waves. The application of EELS to study surface plasmons in nanosized metallic systems is then presented. In particular, we discuss that EELS can provide important information...

  18. Electronic Structure and Spectroscopy of HBr and HBr^+

    Science.gov (United States)

    Vazquez, Gabriel J.; Liebermann, H. P.; Lefebvre-Brion, H.

    2016-06-01

    We report preliminary ab initio electronic structure calculations of HBr and HBr^+. The computations were carried out employing the MRD-CI package, with a basis set of cc-pVQZ quality augmented with s--, p-- and d--type diffuse functions. In a first series of calculations, without inclusion of spin--orbit splitting, potential energy curves of about 20 doublet and quartet electronic states of HBr^+, and about 30 singlet and triplet (valence and Rydberg) states of HBr were computed. This exploratory step provides a perspective of the character, shape, leading configurations, energetics, and asymptotic behaviour of the electronic states. The calculations taking into account spin-orbit are currently being performed. Our study focuses mainly on the Rydberg states and their interactions with the repulsive valence states and with the bound valence ion-pair state. In particular, the current calculations seek to provide information that might be relevant to the interpretation of recent REMPI measurements which involve the interaction between the diabatic E^1Σ^+ Rydberg state and the diabatic V^1Σ^+ ion--pair state (which together constitute the adiabatic, double-well, B^1Σ^+ state). Several new states of both HBr and HBr^+ are reported. D. Zaouris, A. Kartakoullis, P. Glodic, P. C. Samartzis, H. R. Hródmarsson, Á. Kvaran, Phys. Chem. Chem. Phys., 17, 10468 (2015)

  19. Lightning Detection at the Pierre Auger Observatory

    OpenAIRE

    Rautenberg, Julian; Filipčič, Andrej; Kukec Mezek, Gašper; Saleh, Ahmed; Stanič, Samo; Trini, Marta; Veberič, Darko; Vorobiov, Serguei; Yang, Lili; Zavrtanik, Danilo; Zavrtanik, Marko

    2016-01-01

    The Auger Engineering Radio Array, an extension of the Pierre Auger Observatory with antennas in the MHz range, requires to monitor the atmospheric conditions, which have a large influence on the radio emission of air showers. In particular, amplified signals up to an order of magnitude have been detected as an affect of thunderstorms. For a more detailed investigation and more generally, for detecting thunderstorms, a new lightning detection system has been install...

  20. Electron Paramagnetic Resonance Imaging and Spectroscopy of Polydopamine Radicals.

    Science.gov (United States)

    Mrówczyński, Radosław; Coy, L Emerson; Scheibe, Błażej; Czechowski, Tomasz; Augustyniak-Jabłokow, Maria; Jurga, Stefan; Tadyszak, Krzysztof

    2015-08-13

    A thorough investigation of biomimetic polydopamine (PDA) by Electron Paramagnetic Resonance (EPR) is shown. In addition, temperature dependent spectroscopic EPR data are presented in the range 3.8-300 K. Small discrepancies in magnetic susceptibility behavior are observed between previously reported melanin samples. These variations were attributed to thermally acitivated processes. More importantly, EPR spatial-spatial 2D imaging of polydopamine radicals on a phantom is presented for the first time. In consequence, a new possible application of polydopamine as EPR imagining marker is addressed.

  1. X-ray and photoelectron spectroscopy of the structure, reactivity, and electronic structure of semiconductor nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Hamad, Kimberly Sue [Univ. of California, Berkeley, CA (United States)

    2000-01-01

    Semiconductor nanocrystals are a system which has been the focus of interest due to their size dependent properties and their possible use in technological applications. Many chemical and physical properties vary systematically with the size of the nanocrystal and thus their study enables the investigation of scaling laws. Due to the increasing surface to volume ratio as size is decreased, the surfaces of nanocrystals are expected to have a large influence on their electronic, thermodynamic, and chemical behavior. In spite of their importance, nanocrystal surfaces are still relatively uncharacterized in terms of their structure, electronic properties, bonding, and reactivity. Investigation of nanocrystal surfaces is currently limited by what techniques to use, and which methods are suitable for nanocrystals is still being determined. This work presents experiments using x-ray and electronic spectroscopies to explore the structure, reactivity, and electronic properties of semiconductor (CdSe, InAs) nanocrystals and how they vary with size. Specifically, x-ray absorption near edge spectroscopy (XANES) in conjunction with multiple scattering simulations affords information about the structural disorder present at the surface of the nanocrystal. X-ray photoelectron spectroscopy (XPS) and ultra-violet photoelectron spectroscopy (UPS) probe the electronic structure in terms of hole screening, and also give information about band lineups when the nanocrystal is placed in electric contact with a substrate. XPS of the core levels of the nanocrystal as a function of photo-oxidation time yields kinetic data on the oxidation reaction occurring at the surface of the nanocrystal.

  2. X-ray and Auger transition from highly-ionized Ca ions

    Energy Technology Data Exchange (ETDEWEB)

    Karim, K.R.; Logan, L. [Department of Physics, Illinois State University, Normal, Illinois 61790-4560 (United States)] Bhalla, C.P. [Department of Physics, Kansas State University, Manhattan, Kansas 66506 (United States)

    1999-06-01

    We have calculated radiative and Auger transition rates, x-ray wavelengths, lifetimes, and fluorescence yields of variously ionized calcium atoms with electronic configurations 1s2s{sup m}2p{sup n}, (m=0{minus}2, n=1{minus}6) with all allowed values of the orbital angular momentum quantum number {ital l}. The calculation was performed in the intermediate coupling scheme using the Hartree-Fock atomic model. The results from the present calculation have been compared with those available in the literature. Excellent agreement is found in calculated transition energies among the various calculations. The agreement in transition rates is generally good for prominent lines. The radiative and Auger transition rates decrease as electrons are removed from the outer shells. The rate of decrease of Auger transition rates, however, is faster than that of radiative transition rates. The fluorescence yields are found to increase with ionization. {copyright} {ital 1999 American Institute of Physics.}

  3. `Exotic' Electron Spectroscopy of Molecules in Electric Fields

    Science.gov (United States)

    Pathak, Rajeev; Gurav, Nalini; Gejji, Shridhar

    Single molecules, whether polar or non-polar (in their free state), when subjected to an externally applied uniform electric field, are observed to exhibit remarkably different UV spectra from those of their zero-field counterparts. Significant spectral line-shifts, line-splitting, line-merging as well as disappearance, and emergence of `exotic' spectral lines are observed as a function of the applied electric field strength. In particular, we simulate the molecular electronic-transition spectra of methanol, hydrogen-peroxide, water and carbon-dioxide in an electric field, employing time dependent density functional theory (TD-DFT) under the versatile M06-2X dispersion-corrected DFT prescription. It is further demonstrated that the Natural Localized Molecular Orbitals (NLMOs), playing a dual donor-acceptor role, can best describe the electron density redistribution and the interplay of various bands in the UV spectrum which is traced back to mutations and crossings of the frontier molecular orbitals. We would like to thank the Center for Advanced Computing, Pune University Campus, for computer time.

  4. Electron paramagnetic resonance spectroscopy of lithium donors in monoisotopic silicon

    Science.gov (United States)

    Ezhevskii, Alexandr A.; Soukhorukov, Andrey V.; Guseinov, Davud V.; Gusev, Anatoly V.

    2009-12-01

    Electron paramagnetic resonance (X-band EPR) spectra are reported for lithium-related donors in monoisotopic silicon. High resolution EPR spectra of lithium donor centers in monoisotopic silicon, enriched by 28Si isotope (99.99%) with very narrow individual lines are observed. In monoisotopic silicon sample (28Si enriched floating zone silicon with low concentration of lithium 1016 cm-3), the trigonal EPR spectrum, with well resolved 7Li hyperfine structure is recorded in the temperature range 3.5-20 K. This spectrum was attributed to LiO complex. At high concentration of lithium (about 1018 cm-3) in monoisotopic silicon two types of spectra are observed. The trigonal one has the same feature as for low concentration of lithium with g-values: g∥=1.9974 and g⊥=1.9989. Another spectrum consists of two lines and has tetragonal symmetry with g∥=1.9992 and g⊥=1.9983. This spectrum is more intensive than the trigonal one and has no resolved hyperfine structure probably due to time averaging of the hyperfine interaction caused by hopping motion of electrons.

  5. A Comparative Study of Gold Bonding via Electronic Spectroscopy

    Science.gov (United States)

    Zhang, Ruohan

    The bonding and electrostatic properties of gold containing molecules are highly influenced by relativistic effects. To understand this facet on bonding, a series of simple diatomic AuX (X=F, Cl, O and S) molecules, where upon bond formation the Au atom donates or accepts electrons, was investigated and discussed in this thesis. First, the optical field-free, Stark, and Zeeman spectroscopic studies have been performed on AuF and AuCl. The simple polar bonds between Au and typical halogens (i.e. F and Cl) can be well characterized by the electronic structure studies and the permanent electric dipole moments, mu el. The spectroscopic parameters have been precisely determined for the [17.7]1, [17.8]0+ and X1Sigma + states of AuF, and the [17.07]1, [17.20]0+ and X1Sigma+ states of AuCl. The mu el have been determined for ground and excited states of AuF and AuCl. The results from the hyperfine analysis and Stark measurement support the assignments that the [17.7]1 and [17.8]0+ states of AuF are the components of a 3pi state. Similarly, the analysis demonstrated the [19.07]1 and [19.20]0+ states are the components of the 3pi state of AuCl. Second, my study focused on AuO and AuS because the bonding between gold and sulfur/oxygen is a key component to numerous established and emerging technologies that have applications as far ranging as medical imaging, catalysis, electronics, and material science. The high-resolution spectra were record and analyzed to obtain the geometric and electronic structural data for the ground and excited states. The electric dipole moment, muel , and the magnetic dipole moment, mum, has been the precisely measured by applying external static electric and magnetic fields. muel and mum are used to give insight into the unusual complex bonding in these molecules. In addition to direct studies on the gold-containing molecules, other studies of related molecules are included here as well. These works contain the pure rotation measurement of Pt

  6. Operations of and Future Plans for the Pierre Auger Observatory

    Energy Technology Data Exchange (ETDEWEB)

    Abraham, : J.; Abreu, P.; Aglietta, M.; Aguirre, C.; Ahn, E.J.; Allard, D.; Allekotte, I.; Allen, J.; Alvarez-Muniz, J.; Ambrosio, M.; Anchordoqui, L.

    2009-06-01

    These are presentations to be presented at the 31st International Cosmic Ray Conference, in Lodz, Poland during July 2009. It consists of the following presentations: (1) Performance and operation of the Surface Detectors of the Pierre Auger Observatory; (2) Extension of the Pierre Auger Observatory using high-elevation fluorescence telescopes (HEAT); (3) AMIGA - Auger Muons and Infill for the Ground Array of the Pierre Auger Observatory; (4) Radio detection of Cosmic Rays at the southern Auger Observatory; (5) Hardware Developments for the AMIGA enhancement at the Pierre Auger Observatory; (6) A simulation of the fluorescence detectors of the Pierre Auger Observatory using GEANT 4; (7) Education and Public Outreach at the Pierre Auger Observatory; (8) BATATA: A device to characterize the punch-through observed in underground muon detectors and to operate as a prototype for AMIGA; and (9) Progress with the Northern Part of the Pierre Auger Observatory.

  7. Growth and electronic structure of Cu on Cr sub 2 O sub 3 (0001)

    CERN Document Server

    Xiao Wen De; Guo Qi; Wang, E G

    2003-01-01

    The deposition of Cu at room temperature on a Cr sub 2 O sub 3 (0001) substrate is studied by x-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy and low-energy-electron diffraction. The results indicate that at RT Cu is highly dispersed on the substrate at initial deposition. X-ray induced Auger spectra, Auger parameter and ultraviolet photoelectron spectroscopy show that at the initial coverage the deposited Cu is in the Cu(I) state due to the interaction of Cu with the Cr sub 2 O sub 3 substrate; Cu becomes metallic at Cu coverages of > 4 monolayer equivalent. The formation of Cu two-dimensional or quasi-2D patches is followed by the formation of Cu three-dimensional clusters. Cu grows epitaxially on the Cr sub 2 O sub 3 (0001) films as Cu(111)R 30 deg. as observed by low-energy-electron diffraction.

  8. Alpha and conversion electron spectroscopy of 238,239Pu and 241Am and alpha-conversion electron coincidence measurements

    Science.gov (United States)

    Dion, Michael P.; Miller, Brian W.; Warren, Glen A.

    2016-09-01

    A technique to determine the isotopic constituents of a mixed actinide sample has been proposed by a coincident alpha-conversion electron measurement. This presents a unique signature to allow the unfolding of isotopes that possess overlapping alpha particle energy and reduce backgrounds of an unseparated sample. The work presented here are results of conversion electron spectroscopy of 241Am, 238Pu and 239Pu using a dual-stage peltier-cooled 25 mm2 silicon drift detector and alpha spectroscopy with a passivated ion implanted planar silicon detector. The conversion electron spectra were evaluated from 20-55 keV based on fits to the dominant conversion electron emissions, which allowed the relative conversion electron emission intensities to be determined. These measurements provide crucial singles spectral information and calibration to aid in the coincident measurement approach. Furthermore, an alpha-conversion electron spectrometer was assembled using the silicon based detectors described and results of a coincident spectrum analysis is reported for 241Am.

  9. Anisotropic plasmons, excitons, and electron energy loss spectroscopy of phosphorene

    Science.gov (United States)

    Ghosh, Barun; Kumar, Piyush; Thakur, Anmol; Chauhan, Yogesh Singh; Bhowmick, Somnath; Agarwal, Amit

    2017-07-01

    In this article, we explore the anisotropic electron energy loss spectrum (EELS) in monolayer phosphorene based on ab initio time-dependent density-functional-theory calculations. Similarly to black phosphorus, the EELS of undoped monolayer phosphorene is characterized by anisotropic excitonic peaks for energies in the vicinity of the band gap and by interband plasmon peaks for higher energies. On doping, an additional intraband plasmon peak also appears for energies within the band gap. Similarly to other two-dimensional systems, the intraband plasmon peak disperses as ωpl∝√{q } in both the zigzag and armchair directions in the long-wavelength limit and deviates for larger wave vectors. The anisotropy of the long-wavelength plasmon intraband dispersion is found to be inversely proportional to the square root of the ratio of the effective masses: ωpl(q y ̂) /ωpl(q x ̂) =√{mx/my } .

  10. The radiation defect accumulation in scintillative crystals of caesium halides under intense electron beam irradiation

    CERN Document Server

    Galiy, P V

    1999-01-01

    The characteristics of defect accumulation and radiolysis at CsI crystals under mean energies of electron irradiation at wide dose rates and ranges of doses have been investigated by such methods: thermostimulated exoelectron emission (TSEE), Auger electron spectroscopy (AES) and optical absorption spectroscopy (OAS). The limit dose rates and absorbed doses of electron irradiation that lead to defects accumulation at room temperature in crystals volume and also surface stoichiometry violation have been evaluated. The doses of electron irradiation that lead to CsI radiolysis, with caesium coagulation in metallic phase have been determined. Some quasi periodic connection of such process with irradiation dose was observed.

  11. Mapping boron in silicon solar cells using electron energy-loss spectroscopy

    DEFF Research Database (Denmark)

    Duchamp, Martial; Boothroyd, Chris; Kovács, András

    2011-01-01

    Electron energy-loss spectroscopy (EELS) is used to study the B distribution in a p-i-n layered solar cell structure. The boron concentration in the p-doped Si layer is expected to be ~1021 cm−3 and should not exceed 1017 cm−3 in the neighbouring intrinsic layer. We show that B concentrations...

  12. Electron-energy-loss spectroscopy of plasmon excitations in concentric-shell fullerenes

    NARCIS (Netherlands)

    Henrard, L.; Malengreau, F.; Rudolf, P.; Hevesi, K.; Caudano, R.; Lambin, Ph.; Cabioc’h, Th.

    1999-01-01

    We report evidence for surface plasmon excitations in concentric-shell fullerenes. A film of these concentric-shell fullerenes with radii around 5–7 nm was produced by carbon bombardment of a silver polycrystalline target and measured by electron-energy-loss spectroscopy (EELS) in reflection

  13. Probing the local environment of a single OPE3 molecule using inelastic tunneling electron spectroscopy

    NARCIS (Netherlands)

    Frisenda, R.; Perrin, M.L.; Van der Zant, H.S.J.

    2015-01-01

    We study single-molecule oligo(phenylene ethynylene)dithiol junctions by means of inelastic electron tunneling spectroscopy (IETS). The molecule is contacted with gold nano-electrodes formed with the mechanically controllable break junction technique. We record the IETS spectrum of the molecule from

  14. Low Energy Electron-Impact Spectroscopy of C(sup 60) Buckminsterfullerene Molecule

    Science.gov (United States)

    Trajmar, S.; Wang, S.

    1993-01-01

    The methods of electron-impact spectroscopy were utilized to obtain the first low-energy, high-resolution energy-loss spectra of gas phase pure C(sub 60) and C(sub 60) + C(sub 70) mixture buckminsterfullerene molecules.

  15. Local electronic structure of Fe(001) surfaces studied by scanning tunneling spectroscopy

    NARCIS (Netherlands)

    Bischoff, M.M.J.; Yamada, T.K.; Fang, C.M.; Groot, R.A. de; Kempen, H. van

    2003-01-01

    Scanning tunneling spectroscopy is used to study the local electronic structure of Fe(001) whiskers. The influence of a voltage dependent background on the apparent peak energies in the dI/dV curves is discussed. A relation between this background and the apparent barrier height is established. The

  16. In situ light spectroscopy in the environmental transmission electron microscope (ETEM)

    DEFF Research Database (Denmark)

    Cavalca, Filippo; Langhammer, C.; Pedersen, Thomas

    2012-01-01

    with several in situ TEM techniques including environmental transmission electron microscopy (ETEM) [3,4], in situ photo activation and localized surface plasmon resonance (LSPR) spectroscopy [5,6]. ETEM is a well-established technique for material analysis. In this work we implement indirect nanoplasmonic...

  17. Identification and Quantification of Copper Sites in Zeolites by Electron Paramagnetic Resonance Spectroscopy

    DEFF Research Database (Denmark)

    Godiksen, Anita; Vennestrøm, Peter N. R.; Rasmussen, Søren Birk

    2017-01-01

    Recent quantitative electron paramagnetic resonance spectroscopy (EPR) data on different copper species present in copper exchanged CHA zeolites are presented and put into context with the literature on other copper zeolites. Results presented herein were obtained using ex situ and in situ EPR...

  18. Auger Recombination in Self-Assembled Quantum Dots: Quenching and Broadening of the Charged Exciton Transition.

    Science.gov (United States)

    Kurzmann, Annika; Ludwig, Arne; Wieck, Andreas D; Lorke, Axel; Geller, Martin

    2016-05-11

    In quantum dots (QDs), the Auger recombination is a nonradiative process in which the electron-hole recombination energy is transferred to an additional carrier. It has been studied mostly in colloidal QDs, where the Auger recombination time is in the picosecond range and efficiently quenches the light emission. In self-assembled QDs, on the other hand, the influence of Auger recombination on the optical properties is in general neglected, assuming that it is masked by other processes such as spin and charge fluctuations. Here, we use time-resolved resonance fluorescence to analyze the Auger recombination and its influence on the optical properties of a single self-assembled QD. From excitation-power-dependent measurements, we find a long Auger recombination time of about 500 ns and a quenching of the trion transition by about 80%. Furthermore, we observe a broadening of the trion transition line width by up to a factor of 2. With a model based on rate equations, we are able to identify the interplay between tunneling and Auger rate as the underlying mechanism for the reduced intensity and the broadening of the line width. This demonstrates that self-assembled QDs can serve as an ideal model system to study how the charge recapture process, given by the band-structure surrounding the confined carriers, influences the Auger process. Our findings are not only relevant for improving the emission properties of colloidal QD-based emitters and dyes, which have recently entered the consumer market, but also of interest for more visionary applications, such as quantum information technologies, based on self-assembled quantum dots.

  19. Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Hellman, Hal

    1968-01-01

    This booklet discusses spectroscopy, the study of absorption of radiation by matter, including X-ray, gamma-ray, microwave, mass spectroscopy, as well as others. Spectroscopy has produced more fundamental information to the study of the detailed structure of matter than any other tools.

  20. Sequential double Auger decay in atoms: A quantum informatic analysis

    Energy Technology Data Exchange (ETDEWEB)

    Parida, S. [Department of Physics and Meteorology, Indian Institute of Technology, Kharagpur 721302 (India); Chandra, N. [Department of Physics and Meteorology, Indian Institute of Technology, Kharagpur 721302 (India)], E-mail: ncphy@phy.iitkgp.ernet.in

    2009-05-04

    We theoretically show that the process of inner-shell photoionization in an atom A, followed by the spontaneous sequential emission of two Auger electrons, produces various kinds of spin-entangled states of three flying electronic qubits. All properties of these states are completely pre-determined by the total spin quantum numbers of the electronic states of four atomic species (i.e., A, A{sup +{sup *}}, A{sup 2+{sup *}}, A{sup 3+}) participating in this process in the Russell-Saunders coupling. These tripartite states are readily characterized experimentally by measuring only energies of the three emitted electrons, without requiring any entanglement witness or other such protocols.

  1. Monitoring of alcoholic fermentation using near infrared and mid infrared spectroscopies combined with electronic nose and electronic tongue

    Energy Technology Data Exchange (ETDEWEB)

    Buratti, S., E-mail: susanna.buratti@unimi.it [Department of Food Science and Technology, Universita degli Studi di Milano, Via Celoria 2, 20133 Milano (Italy); Ballabio, D. [Department of Environmental Sciences, University of Milano-Bicocca, Piazza della Scienza 1, 20126 Milano (Italy); Giovanelli, G. [Department of Food Science and Technology, Universita degli Studi di Milano, Via Celoria 2, 20133 Milano (Italy); Dominguez, C.M. Zuluanga [Instituto de Ciencia y Tecnologia de Alimentos, Universidad Nacional de Colombia, Ciudad Universitaria, Bogota (Colombia); Moles, A.; Benedetti, S.; Sinelli, N. [Department of Food Science and Technology, Universita degli Studi di Milano, Via Celoria 2, 20133 Milano (Italy)

    2011-07-04

    Graphical abstract: Application of non destructive methods for the monitoring of red wine fermentation in correlation with the evolution of chemical parameters. Highlights: > We monitored time-related changes in red wine fermentation process. > NIR and MIR spectroscopies, electronic nose and tongue were applied. > Data were kinetically modelled to identify critical points during fermentation. > NIR, MIR electronic nose and tongue were able to follow the fermentation process. > The models agreed with the evolution of chemical parameters. - Abstract: Effective fermentation monitoring is a growing need due to the rapid pace of change in the wine industry, which calls for fast methods providing real time information in order to assure the quality of the final product. The objective of this work is to investigate the potential of non-destructive techniques associated with chemometric data analysis, to monitor time-related changes that occur during red wine fermentation. Eight micro-fermentation trials conducted in the Valtellina region (Northern Italy) during the 2009 vintage, were monitored by a FT-NIR and a FT-IR spectrometer and by an electronic nose and tongue. The spectroscopic technique was used to investigate molecular changes, while electronic nose and electronic tongue evaluated the evolution of the aroma and taste profile during the must-wine fermentation. Must-wine samples were also analysed by traditional chemical methods in order to determine sugars (glucose and fructose) consumption and alcohol (ethanol and glycerol) production. Principal Component Analysis was applied to spectral, electronic nose and electronic tongue data, as an exploratory tool, to uncover molecular, aroma and taste modifications during the fermentation process. Furthermore, the chemical data and the PC1 scores from spectral, electronic nose and electronic tongue data were modelled as a function of time to identify critical points during fermentation. The results showed that NIR and MIR

  2. Spectroscopy

    CERN Document Server

    Walker, S

    1976-01-01

    The three volumes of Spectroscopy constitute the one comprehensive text available on the principles, practice and applications of spectroscopy. By giving full accounts of those spectroscopic techniques only recently introduced into student courses - such as Mössbauer spectroscopy and photoelectron spectroscopy - in addition to those techniques long recognised as being essential in chemistry teaching - sucha as e.s.r. and infrared spectroscopy - the book caters for the complete requirements of undergraduate students and at the same time provides a sound introduction to special topics for graduate students.

  3. First-Principles Vibrational Electron Energy Loss Spectroscopy of β -Guanine

    Science.gov (United States)

    Radtke, G.; Taverna, D.; Lazzeri, M.; Balan, E.

    2017-07-01

    A general approach to model vibrational electron energy loss spectra obtained using an electron beam positioned away from the specimen is presented. The energy-loss probability of the fast electron is evaluated using first-principles quantum mechanical calculations (density functional theory) of the dielectric response of the specimen. The validity of the method is assessed using recently measured anhydrous β -guanine, an important molecular solid used by animals to produce structural colors. The good agreement between theory and experiments lays the basis for a quantitative interpretation of this spectroscopy in complex systems.

  4. Optimization of Monochromated TEM for Ultimate Resolution Imaging and Ultrahigh Resolution Electron Energy Loss Spectroscopy

    KAUST Repository

    Lopatin, Sergei

    2017-09-01

    The performance of a monochromated transmission electron microscope with Wien type monochromator is optimized to achieve an extremely narrow energy spread of electron beam and an ultrahigh energy resolution with spectroscopy. The energy spread in the beam is improved by almost an order of magnitude as compared to specified values. The optimization involves both the monochromator and the electron energy loss detection system. We demonstrate boosted capability of optimized systems with respect to ultra-low loss EELS and sub-angstrom resolution imaging (in a combination with spherical aberration correction).

  5. Probing interfacial electron dynamics with time-resolved X-ray spectroscopy

    Science.gov (United States)

    Neppl, Stefan

    2015-05-01

    Time-resolved core-level spectroscopy techniques using laser pulses to initiate and short X-ray pulses to probe photo-induced processes have the potential to provide electronic state- and atomic site-specific insight into fundamental electron dynamics at complex interfaces. We describe the implementation of femto- and picosecond time-resolved photoelectron spectroscopy at the Linac Coherent Light Source (LCLS) and at the Advanced Light Source (ALS) in order to follow light-driven electron dynamics at dye-semiconductor interfaces on femto- to nanosecond timescales, and from the perspective of individual atomic sites. A distinct transient binding-energy shift of the Ru3d photoemission lines originating from the metal centers of N3 dye-molecules adsorbed on nanoporous ZnO is observed 500 fs after resonant HOMO-LUMO excitation with a visible laser pulse. This dynamical chemical shift is accompanied by a characteristic surface photo-voltage response of the semiconductor substrate. The two phenomena and their correlation will be discussed in the context of electronic bottlenecks for efficient interfacial charge-transfer and possible charge recombination and relaxation pathways leading to the neutralization of the transiently oxidized dye following ultrafast electron injection. First steps towards in operando time-resolved X-ray absorption spectroscopy techniques to monitor interfacial chemical dynamics will be presented.

  6. Electronic Spectroscopy of Phthalocyanine and Porphyrin Derivatives in Superfluid Helium Nanodroplets.

    Science.gov (United States)

    Slenczka, Alkwin

    2017-07-25

    Phthalocyanine and porphyrin were among the first organic compounds investigated by means of electronic spectroscopy in superfluid helium nanodroplets. Superfluid helium nanodroplets serve as a very gentle host system for preparing cold and isolated molecules. The uniqueness of helium nanodroplets is with respect to the superfluid phase which warrants the vanishing viscosity and, thus, minimal perturbation of the dopant species at a temperature as low as 0.37 K. These are ideal conditions for the study of molecular spectra in order to analyze structures as well as dynamic processes. Besides the investigation of the dopant species itself, molecular spectroscopy in helium droplets provides information on the helium droplet and in particular on microsolvation. This article, as part of a special issue on phthalocyanines and porphyrins, reviews electronic spectroscopy of phthalocyanine and porphyrin compounds in superfluid helium nanodroplets. In addition to the wide variety of medical as well as technical and synthetical aspects, this article discusses electronic spectroscopy of phthalocyanines and porphyrins in helium droplets in order to learn about both the dopant and the helium environment.

  7. Scanning electron microscopy and X-ray spectroscopy applied to mycelial phase of sporothrix schenckii

    Directory of Open Access Journals (Sweden)

    M. Thibaut

    1975-04-01

    Full Text Available Scanning electron microscopy applied to the mycelial phase of Sporothrix schenckii shows a matted mycelium with conidia of a regular pattern. X-Ray microanalysis applied in energy dispersive spectroscopy and also in wavelength dispersive spectroscopy reveals the presence of several elements of Mendeleef's classification.Sporothrix schenckii foi estudado em microscopia eletrônica. Foram observados caracteres das hífas e dos esporos, vários elementos da classificação periódica foram postos em evidência graças à micro-análise a raios X.

  8. Electronically tunable coherent Raman spectroscopy using acousto-optics tunable filter.

    Science.gov (United States)

    Petrov, Georgi I; Meng, Zhaokai; Yakovlev, Vladislav V

    2015-09-21

    Fast and sensitive Raman spectroscopy measurements are imperative for a large number of applications in biomedical imaging, remote sensing and material characterization. In this report, by introducing an electronically-tunable acousto-optical filter as a wavelength selector, we demonstrated a novel instrumentation to the broadband coherent Raman spectroscopy. System's tunability allows assessing Raman transitions ranging from <400 cm(-1) to 4500 cm(-1). We validated the use of the new instrumentation by collecting coherent anti-Stokes spectra and stimulated Raman spectra of various samples.

  9. Auger generation as an intrinsic limit to tunneling field-effect transistor performance

    Science.gov (United States)

    Teherani, James T.; Agarwal, Sapan; Chern, Winston; Solomon, Paul M.; Yablonovitch, Eli; Antoniadis, Dimitri A.

    2016-08-01

    Many in the microelectronics field view tunneling field-effect transistors (TFETs) as society's best hope for achieving a >10× power reduction for electronic devices; however, despite a decade of considerable worldwide research, experimental TFET results have significantly underperformed simulations and conventional MOSFETs. To explain the discrepancy between TFET experiments and simulations, we investigate the parasitic leakage current due to Auger generation, an intrinsic mechanism that cannot be mitigated with improved material quality or better device processing. We expose the intrinsic link between the Auger and band-to-band tunneling rates, highlighting the difficulty of increasing one without the other. From this link, we show that Auger generation imposes a fundamental limit on ultimate TFET performance.

  10. Auger generation as an intrinsic limit to tunneling field-effect transistor performance

    Energy Technology Data Exchange (ETDEWEB)

    Teherani, James T., E-mail: j.teherani@columbia.edu [Department of Electrical Engineering, Columbia University, New York, New York 10027 (United States); Agarwal, Sapan [Sandia National Laboratories, Albuquerque, New Mexico 87123 (United States); Chern, Winston; Antoniadis, Dimitri A. [Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Solomon, Paul M. [IBM T.J. Watson Research Center, Yorktown Heights, New York 10598 (United States); Yablonovitch, Eli [Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, California 94720 (United States)

    2016-08-28

    Many in the microelectronics field view tunneling field-effect transistors (TFETs) as society's best hope for achieving a >10× power reduction for electronic devices; however, despite a decade of considerable worldwide research, experimental TFET results have significantly underperformed simulations and conventional MOSFETs. To explain the discrepancy between TFET experiments and simulations, we investigate the parasitic leakage current due to Auger generation, an intrinsic mechanism that cannot be mitigated with improved material quality or better device processing. We expose the intrinsic link between the Auger and band-to-band tunneling rates, highlighting the difficulty of increasing one without the other. From this link, we show that Auger generation imposes a fundamental limit on ultimate TFET performance.

  11. Ultrafast Charge Transfer Processes Accompanying K L L Auger Decay in Aqueous KCl Solution

    Science.gov (United States)

    Céolin, D.; Kryzhevoi, N. V.; Nicolas, Ch.; Pokapanich, W.; Choksakulporn, S.; Songsiriritthigul, P.; Saisopa, T.; Rattanachai, Y.; Utsumi, Y.; Palaudoux, J.; Öhrwall, G.; Rueff, J.-P.

    2017-12-01

    X-ray photoelectron and K L L Auger spectra were measured for the K+ and Cl- ions in aqueous KCl solution. While the XPS spectra of these ions have similar structures, both exhibiting only weak satellites near the main line, the Auger spectra differ dramatically. Contrary to the chloride case, a very strong extra peak was found in the Auger spectrum of K+ at the low kinetic energy side of the D 1 state. Using the equivalent core model and ab initio calculations this spectral feature was assigned to electron transfer processes from solvent water molecules to the solvated cation. The observed charge transfer processes are suggested to play an important role in charge redistribution following single and multiple core-hole creation in atoms and molecules placed into environment.

  12. Development of broad bandwidth nonlinear spectroscopies for characterization of electronic states in materials systems

    Science.gov (United States)

    Mehlenbacher, Randy D.

    Carbon nanotubes are an interesting class of materials with many exceptional properties that make them appealing for optoelectronic devices. Their optical properties, particularly when cast in thin films, are not well understood. In this thesis, I describe the development of spectroscopic techniques for measuring energy and charge transport processes in thin films of semiconducting carbon nanotubes. Using transient absorption spectroscopy, I observe energy transport on two time scales in these films, with 20% of nanotubes transferring energy to smaller bandgap nanotubes within 300 fs. After 3 ps, 70% of the photoexcitation resides on small bandgap nanotubes. To study the complete landscape of energy transport in thin films of carbon nanotubes, I developed two dimensional white light spectroscopy (2D-WL). In 2D-WL spectroscopy, a broadband, white light supercontinuum is used to both excite and probe the sample. This technique has a bandwidth spanning > 500-1500 nm, a far broader bandwidth than previously reported in 2D electronic spectra. I take advantage of this large bandwidth to study the interactions and evolution of S1 and S2 excitons in a thin film of carbon nanotubes. I find that energy transfers between S1 excitons on a 2 ps time scale and occurs by a non-Forster energy transfer mechanism. In contrast, the energy in the S2 states redistributes on an ultrafast time scale, electrons and holes. I use 2D-WL spectroscopy to study the electronic states in thin films of bare, semiconducting carbon nanotubes. In these films, energy transfer occurs in electronic states. To facilitate data interpretation, the orientational response for isotropic two dimensional samples to polarized electric fields is developed. Using polarization control 2D-WL spectroscopy, I measure the coupling between nanotube S1 transitions and radial breathing modes. The doped tubes form trions with transition dipoles that are not parallel to the S1 transition and energy transfer from the S1

  13. A position-sensitive electron detector for use in electron spectroscopy

    CERN Document Server

    Hubin-Franskin, M J

    2002-01-01

    A home-made position-sensitive electron detection system has been mounted on an electron energy loss spectrometer. It makes use of advanced technology, is easy to handle with and not too expensive. The K-shell excitation spectrum of benzene is given as an example of the quality of the signal-to-noise ratio while keeping the resolution.

  14. High-energy-resolution monochromator for aberration-corrected scanning transmission electron microscopy/electron energy-loss spectroscopy.

    Science.gov (United States)

    Krivanek, Ondrej L; Ursin, Jonathan P; Bacon, Neil J; Corbin, George J; Dellby, Niklas; Hrncirik, Petr; Murfitt, Matthew F; Own, Christopher S; Szilagyi, Zoltan S

    2009-09-28

    An all-magnetic monochromator/spectrometer system for sub-30 meV energy-resolution electron energy-loss spectroscopy in the scanning transmission electron microscope is described. It will link the energy being selected by the monochromator to the energy being analysed by the spectrometer, without resorting to decelerating the electron beam. This will allow it to attain spectral energy stability comparable to systems using monochromators and spectrometers that are raised to near the high voltage of the instrument. It will also be able to correct the chromatic aberration of the probe-forming column. It should be able to provide variable energy resolution down to approximately 10 meV and spatial resolution less than 1 A.

  15. Applications of aberration corrected scanning transmission electron microscopy and electron energy loss spectroscopy to thin oxide films and interfaces.

    Energy Technology Data Exchange (ETDEWEB)

    Varela del Arco, Maria [ORNL; Gazquez Alabart, Jaume [ORNL; Lupini, Andrew R [ORNL; Luck, Julia T [ORNL; Torija, Maria [University of Minnesota; Sharma, M [University of Minnesota; Leighton, chris [University of Minnesota; Biegalski, Michael D [ORNL; Christen, Hans M [ORNL; Murfitt, Matt [Nion Co; Dellby, Niklas [ORNL; Krivanek, Ondrej [ORNL; Pennycook, Stephen J [ORNL

    2010-01-01

    Aberration correction in the scanning transmission electron microscope allows spatial resolutions of the order of one ngstr m to be routinely achieved. When combined with electron energy loss spectroscopy, it is possible to simultaneously map the structure, the chemistry and even the electronic properties of materials in one single experiment. Here we will apply these techniques to the characterization of thin films and interfaces based on complex oxides with the perovskite structure. The relatively large lattice parameter of these materials combined with the fact that most of them have absorption edges within the reach of the spectrometer optics makes these materials ideal for these experiments. We will show how it is possible to map the chemistry of interfaces atomic plane by atomic plane, including light element imaging such as O. Applications to cobaltite and titanate thin films will be described.

  16. Communication: Coherences observed in vivo in photosynthetic bacteria using two-dimensional electronic spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Dahlberg, Peter D. [Graduate Program in the Biophysical Sciences, Institute for Biophysical Dynamics, and The James Franck Institute, The University of Chicago, Chicago, Illinois 60637 (United States); Norris, Graham J.; Wang, Cheng; Viswanathan, Subha; Singh, Ved P.; Engel, Gregory S., E-mail: gsengel@uchicago.edu [Department of Chemistry, Institute for Biophysical Dynamics, and The James Franck Institute, The University of Chicago, Chicago, Illinois 60637 (United States)

    2015-09-14

    Energy transfer through large disordered antenna networks in photosynthetic organisms can occur with a quantum efficiency of nearly 100%. This energy transfer is facilitated by the electronic structure of the photosynthetic antennae as well as interactions between electronic states and the surrounding environment. Coherences in time-domain spectroscopy provide a fine probe of how a system interacts with its surroundings. In two-dimensional electronic spectroscopy, coherences can appear on both the ground and excited state surfaces revealing detailed information regarding electronic structure, system-bath coupling, energy transfer, and energetic coupling in complex chemical systems. Numerous studies have revealed coherences in isolated photosynthetic pigment-protein complexes, but these coherences have not been observed in vivo due to the small amplitude of these signals and the intense scatter from whole cells. Here, we present data acquired using ultrafast video-acquisition gradient-assisted photon echo spectroscopy to observe quantum beating signals from coherences in vivo. Experiments were conducted on isolated light harvesting complex II (LH2) from Rhodobacter sphaeroides, whole cells of R. sphaeroides, and whole cells of R. sphaeroides grown in 30% deuterated media. A vibronic coherence was observed following laser excitation at ambient temperature between the B850 and the B850{sup ∗} states of LH2 in each of the 3 samples with a lifetime of ∼40-60 fs.

  17. Nanoscale probing of bandgap states on oxide particles using electron energy-loss spectroscopy.

    Science.gov (United States)

    Liu, Qianlang; March, Katia; Crozier, Peter A

    2017-07-01

    Surface and near-surface electronic states were probed with nanometer spatial resolution in MgO and TiO2 anatase nanoparticles using ultra-high energy resolution electron energy-loss spectroscopy (EELS) coupled to a scanning transmission electron microscope (STEM). This combination allows the surface electronic structure determined with spectroscopy to be correlated with nanoparticle size, morphology, facet etc. By acquiring the spectra in aloof beam mode, radiation damage to the surface can be significantly reduced while maintaining the nanometer spatial resolution. MgO and TiO2 showed very different bandgap features associated with the surface/sub-surface layer of the nanoparticles. Spectral simulations based on dielectric theory and density of states models showed that a plateau feature found in the pre-bandgap region in the spectra from (100) surfaces of 60nm MgO nanocubes is consistent with a thin hydroxide surface layer. The spectroscopy shows that this hydroxide species gives rise to a broad filled surface state at 1.1eV above the MgO valence band. At the surfaces of TiO2 nanoparticles, pronounced peaks were observed in the bandgap region, which could not be well fitted to defect states. In this case, the high refractive index and large particle size may make Cherenkov or guided light modes the likely causes of the peaks. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. A Complete Overhaul of the Electron Energy-Loss Spectroscopy and X-Ray Absorption Spectroscopy Database: eelsdb.eu.

    Science.gov (United States)

    Ewels, Philip; Sikora, Thierry; Serin, Virginie; Ewels, Chris P; Lajaunie, Luc

    2016-06-01

    The electron energy-loss spectroscopy (EELS) and X-ray absorption spectroscopy (XAS) database has been completely rewritten, with an improved design, user interface, and a number of new tools. The database is accessible at https://eelsdb.eu/ and can now be used without registration. The submission process has been streamlined to encourage spectrum submissions and the new design gives greater emphasis on contributors' original work by highlighting their papers. With numerous new filters and a powerful search function, it is now simple to explore the database of several hundred EELS and XAS spectra. Interactive plots allow spectra to be overlaid, facilitating online comparison. An application-programming interface has been created, allowing external tools and software to easily access the information held within the database. In addition to the database itself, users can post and manage job adverts and read the latest news and events regarding the EELS and XAS communities. In accordance with the ongoing drive toward open access data increasingly demanded by funding bodies, the database will facilitate open access data sharing of EELS and XAS spectra.

  19. 30 CFR 77.1500 - Auger mining; planning.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Auger mining; planning. 77.1500 Section 77.1500 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR COAL MINE SAFETY AND HEALTH... § 77.1500 Auger mining; planning. Auger mining shall be planned and conducted by the operator to insure...

  20. Spectromicroscopy of Polymers: Comparison of Radiation Damage with Electron and Photon Core Excitation Spectroscopy Techniques

    Science.gov (United States)

    Ade, H.; Smith, A. P.; Rightor, E. G.; Hitchcock, A. P.; Urquhart, S.; Leapman, R.

    1997-03-01

    Core excitation microspectroscopy has become a powerful tool for the characterization of polymeric materials due to its sensitivity to chemical functionality. However, the excitations utilized in electron energy loss spectroscopy performed in a scanning transmission electron microscope (TEM-EELS) and near edge x-ray absorption fine structure (NEXAFS) spectroscopy can introduce radiation damage and chemically modify the sample. In order to understand the radiation damage associated with TEM-EELS and NEXAFS spectroscopy we have studied the radiation damage of the common polymer poly(ethylene terephthalate) (PET) as exhibited by changes in the acquired C K-edge excitation spectra. By fitting gaussian functions to the spectral intensity changes as a function of dose, we have determined the critical radiation dose of PET for both NEXAFS spectroscopy and TEM-EELS under typical operating conditions. This critical radiation dose for TEM-EELS is found to be 1.7 ± 0.2 x 10^8 grey (1.7 ± 0.2 x 10^4 Mrad) compared to a critical radiation dose for NEXAFS spectroscopy of 1.4 ± 0.7 x 10^9 grey (1.4 ± 0.7 x 10^5 Mrad). By considering the G factors of the two techniques and the critical radiation dose, a rule of thumb was derived that indicates that with typical present operating conditions, NEXAFS spectroscopy can analyze areas 500 times smaller than TEM-EELS given the same amount of radiation damage. Work supported by: NSF Young Investigator Award (DMR-9458060) and Dow Chemical

  1. High-resolution electron collision spectroscopy with multicharged ions in merged beams

    Energy Technology Data Exchange (ETDEWEB)

    Lestinsky, M.

    2007-04-18

    The Heidelberg ion storage ring Tsr is currently the only ring equipped with two independent devices for the collinear merging of a cold electron beam with stored ions. This greatly improves the potential of electron-ion collision experiments, as the ion beam can be cooled with one electron beam, while the other one is used as a dedicated target for energy-resolved electron collision processes, such as recombination. The work describes the implementation of this system for rst electron collision spectroscopy experiments. A detection system has been realized including an ion detector and specroscopic beam-control software and instrumentation. Moreover, in order to improve the spectroscopic resolution systematical studies of intrinsic relaxation processes in the electron beam have been carried out. These include the dependence on the electron beam density, the magnetic guiding eld strength, and the acceleration geometry. The recombination measurements on low-lying resonances in lithiumlike Sc{sup 18+} yield a high-precision measurement of the 2s-2p{sub 3/2} transition energy in this system. Operation of the two-electron-beam setup at high collision energy ({approx}1000 eV) is established using resonances of hydrogenlike Mg{sup 11+}, while the unique possibility of modifying the beam-merging geometry con rms its importance for the electron-ion recombination rate at lowest relative energy, as demonstrated on F{sup 6+}. (orig.)

  2. Thermodynamic basis of electron transfer in dihydroorotate dehydrogenase B from Lactococcus lactis: analysis by potentiometry, EPR spectroscopy, and ENDOR spectroscopy.

    Science.gov (United States)

    Mohsen, Al-Walid A; Rigby, Stephen E J; Jensen, Kaj Frank; Munro, Andrew W; Scrutton, Nigel S

    2004-06-01

    Dihydroorotate dehydrogenase B (DHODB) is a complex iron-sulfur flavoprotein that catalyzes the conversion of dihydroorotate to orotate and the reduction of NAD(+). The enzyme is a dimer of heterodimers containing an FMN, an FAD, and a 2Fe-2S center. UV-visible, EPR, and ENDOR spectroscopies have been used to determine the reduction potentials of the flavins and the 2Fe-2S center and to characterize radicals and their interactions. Reductive titration using dithionite indicates a five-electron capacity for DHODB. The midpoint reduction potential of the 2Fe-2S center (-212 +/- 3 mV) was determined from analysis of absorption data at 540 nm, where absorption contributions from the two flavins are small. The midpoint reduction potentials of the oxidized/semiquinone (E(1)) and semiquinone/hydroquinone (E(2)) couples for the FMN (E(1) = -301 +/- 6 mV; E(2) = -252 +/- 8 mV) and FAD (E(1) = -312 +/- 6 mV; E(2) = -297 +/- 5 mV) were determined from analysis of spectral changes at 630 nm. Corresponding values for the midpoint reduction potentials for FMN (E(1) = -298 +/- 4 mV; E(2) = -259 +/- 5 mV) in the isolated catalytic subunit (subunit D, which lacks the 2Fe-2S center and FAD) are consistent with the values determined for the FMN couples in DHODB. During reductive titration of DHODB, small amounts of the neutral blue semiquinone are observed at approximately 630 nm, consistent with the measured midpoint reduction potentials of the flavins. An ENDOR spectrum of substrate-reduced DHODB identifies hyperfine couplings to proton nuclei similar to those recorded for the blue semiquinone of free flavins in aqueous solution, thus confirming the presence of this species in DHODB. Spectral features observed during EPR spectroscopy of dithionite-reduced DHODB are consistent with the midpoint reduction potentials determined using UV-visible spectroscopy and further identify an unusual EPR signal with very small rhombic anisotropy and g values of 2.02, 1.99, and 1.96. This unusual

  3. Signatures of Herzberg-Teller coupling in three-dimensional electronic spectroscopy

    Science.gov (United States)

    Bizimana, Laurie A.; Carbery, William P.; Gellen, Tobias A.; Turner, Daniel B.

    2017-02-01

    The coupling between electronic and nuclear variables is a key consideration in molecular dynamics and spectroscopy. However, simulations that include detailed vibronic coupling terms are challenging to perform, and thus a variety of approximations can be used to model and interpret experimental results. Recent work shows that these simplified models can be inadequate. It is therefore important to understand spectroscopic signals that can identify failures of those approximations. Here we use an extended response-function method to simulate coherent three-dimensional electronic spectroscopy (3D ES) and study the sensitivity of this method to the breakdown of the Franck-Condon approximation. The simulations include a coordinate-dependent transition dipole operator that produces nodes, phase shifts, and peak patterns in 3D ES that can be used to identify Herzberg-Teller coupling. Guided by the simulation results, we interpret measurements on a molecular aggregate.

  4. Direct observation of multistep energy transfer in LHCII with fifth-order 3D electronic spectroscopy

    Science.gov (United States)

    Zhang, Zhengyang; Lambrev, Petar H.; Wells, Kym L.; Garab, Győző; Tan, Howe-Siang

    2015-07-01

    During photosynthesis, sunlight is efficiently captured by light-harvesting complexes, and the excitation energy is then funneled towards the reaction centre. These photosynthetic excitation energy transfer (EET) pathways are complex and proceed in a multistep fashion. Ultrafast two-dimensional electronic spectroscopy (2DES) is an important tool to study EET processes in photosynthetic complexes. However, the multistep EET processes can only be indirectly inferred by correlating different cross peaks from a series of 2DES spectra. Here we directly observe multistep EET processes in LHCII using ultrafast fifth-order three-dimensional electronic spectroscopy (3DES). We measure cross peaks in 3DES spectra of LHCII that directly indicate energy transfer from excitons in the chlorophyll b (Chl b) manifold to the low-energy level chlorophyll a (Chl a) via mid-level Chl a energy states. This new spectroscopic technique allows scientists to move a step towards mapping the complete complex EET processes in photosynthetic systems.

  5. Signatures of Herzberg-Teller coupling in three-dimensional electronic spectroscopy.

    Science.gov (United States)

    Bizimana, Laurie A; Carbery, William P; Gellen, Tobias A; Turner, Daniel B

    2017-02-28

    The coupling between electronic and nuclear variables is a key consideration in molecular dynamics and spectroscopy. However, simulations that include detailed vibronic coupling terms are challenging to perform, and thus a variety of approximations can be used to model and interpret experimental results. Recent work shows that these simplified models can be inadequate. It is therefore important to understand spectroscopic signals that can identify failures of those approximations. Here we use an extended response-function method to simulate coherent three-dimensional electronic spectroscopy (3D ES) and study the sensitivity of this method to the breakdown of the Franck-Condon approximation. The simulations include a coordinate-dependent transition dipole operator that produces nodes, phase shifts, and peak patterns in 3D ES that can be used to identify Herzberg-Teller coupling. Guided by the simulation results, we interpret measurements on a molecular aggregate.

  6. Principles of ESCA and applications to metal corrosion, coating and lubrication. [Electron Spectroscopy for Chemical Analysis

    Science.gov (United States)

    Wheeler, D. R.

    1978-01-01

    The principles of ESCA (electron spectroscopy for chemical analysis) are described by comparison with other spectroscopic techniques. The advantages and disadvantages of ESCA as compared to other surface sensitive analytical techniques are evaluated. The use of ESCA is illustrated by actual applications to oxidation of steel and Rene 41, the chemistry of lubricant additives on steel, and the composition of sputter deposited hard coatings. Finally, a bibliography of material that is useful for further study of ESCA is presented and commented upon.

  7. Vibrational Inelastic Electron Tunneling Spectroscopy of Surface Adsorbed Single Molecules at Sub-Kelvin Temperature

    OpenAIRE

    Jiang, Chi-Lun

    2015-01-01

    With a 600mk homebuilt UHV STM system, we studied molecular vibration at the solid surface with inelastic electron tunneling spectroscopy (IETS) of Acetylene single molecules adsorbed on Cu(100) surface and revealed five new vibrational modes that were previously inaccessible to STM-IETS at 8K temperature. The identification of vibrational IETS features with normalized conductance change (Δσ/σ) as low as 0.24% was demonstrated. Facilitated by the high energy resolution, we also revealed the a...

  8. Inductive-detection electron-spin resonance spectroscopy with 65 spins/ √{Hz } sensitivity

    Science.gov (United States)

    Probst, S.; Bienfait, A.; Campagne-Ibarcq, P.; Pla, J. J.; Albanese, B.; Da Silva Barbosa, J. F.; Schenkel, T.; Vion, D.; Esteve, D.; Mølmer, K.; Morton, J. J. L.; Heeres, R.; Bertet, P.

    2017-11-01

    We report electron spin resonance spectroscopy measurements performed at millikelvin temperatures in a custom-built spectrometer comprising a superconducting micro-resonator at 7 GHz and a Josephson parametric amplifier. Owing to the small ( ˜10-12λ3 ) magnetic resonator mode volume and to the low noise of the parametric amplifier, the spectrometer's single shot sensitivity reaches 260 ± 40 spins/echo translating into 65 ±10 spins/√{Hz } for repeated acquisition.

  9. Probing flexible conformations in molecular junctions by inelastic electron tunneling spectroscopy

    Directory of Open Access Journals (Sweden)

    Mingsen Deng

    2015-01-01

    Full Text Available The probe of flexible molecular conformation is crucial for the electric application of molecular systems. We have developed a theoretical procedure to analyze the couplings of molecular local vibrations with the electron transportation process, which enables us to evaluate the structural fingerprints of some vibrational modes in the inelastic electron tunneling spectroscopy (IETS. Based on a model molecule of Bis-(4-mercaptophenyl-ether with a flexible center angle, we have revealed and validated a simple mathematical relationship between IETS signals and molecular angles. Our results might open a route to quantitatively measure key geometrical parameters of molecular junctions, which helps to achieve precise control of molecular devices.

  10. Combined in-beam gamma-ray and conversion electron spectroscopy with radioactive ion beams

    Directory of Open Access Journals (Sweden)

    Konki J.

    2013-12-01

    Full Text Available In-beam gamma-ray and electron spectroscopy have been widely used as tools to study the broad variety of phenomena in nuclear structure. The SPEDE spectrometer is a new device to be used in conjunction with the MINIBALL germanium detector array to enable the detection of internal conversion electrons in coincidence with gamma rays from de-exciting nuclei in radioactive ion beam experiments at the upcoming HIE-ISOLDE facility at CERN, Switzerland. Geant4 simulations were carried out in order to optimise the design and segmentation of the silicon detector to achieve good energy resolution and performance.

  11. Intermolecular interaction effect on the inelastic electron tunneling spectroscopy of bi-octane-monothiol junctions

    Science.gov (United States)

    Leng, Jiancai; Zhao, Liyun; Zhang, Yujin; Ma, Hong

    2017-01-01

    The inelastic electron tunneling spectroscopy (IETS) of bi-octane-monothiol junctions is theoretically studied based on first-principles calculations. The results reveal that IETS is very sensitive to the vertical and lateral distance of the two molecules in the bimolecular junctions owing to the changes of interaction between the two molecules. It is further demonstrated that the transverse vibrational modes ν(C-H) around 0.38 V will be triggered when the two molecules are close to each other and open a new path for electron tunneling. Our theoretical results provide new insight into understanding the origin of the IETS peaks around 0.38 V.

  12. Electronic states of Myricetin. UV-Vis polarization spectroscopy and quantum chemical calculations.

    Science.gov (United States)

    Vojta, Danijela; Karlsen, Eva Marie; Spanget-Larsen, Jens

    2017-02-15

    Myricetin (3,3',4',5,5',7'-hexahydroxyflavone) was investigated by linear dichroism spectroscopy on molecular samples partially aligned in stretched poly(vinyl alcohol) (PVA). At least five electronic transitions in the range 40,000-20,000cm(-1) were characterized with respect to their wavenumbers, relative intensities, and transition moment directions. The observed bands were assigned to electronic transitions predicted with TD-B3LYP/6-31+G(d,p). Copyright © 2016 Elsevier B.V. All rights reserved.

  13. Employing NMR Spectroscopy To Evaluate Transmission of Electronic Effects in 4-Substituted Chalcones

    Science.gov (United States)

    Wachter-Jurcsak, Nanette; Zamani, Hossein

    1999-05-01

    Described is an organic synthesis experiment that demonstrates the electronic transmission by substituents. The effect of substitution at the para-position of the styryl ring of 1,3-diphenyl-2-propenones (chalcones) by typical electron-donating or -accepting groups can be observed by proton and carbon-13 NMR spectroscopy. A linear correlation is observed when the differences in chemical shift measurements for H are plotted against the corresponding Hammett substituent constant values. Good correlation between carbon-13 chemical shifts of the alpha carbon are also observed. The syntheses of the 4-substituted chalcones is presented as well as a brief discussion of the theory.

  14. In vivo imaging of a stable paramagnetic probe by pulsed-radiofrequency electron paramagnetic resonance spectroscopy

    DEFF Research Database (Denmark)

    Murugesan; Cook; Devasahayam

    1997-01-01

    Imaging of free radicals by electron paramagnetic resonance (EPR) spectroscopy using time domain acquisition as in nuclear magnetic resonance (NMR) has not been attempted because of the short spin-spin relaxation times, typically under 1 μs, of most biologically relevant paramagnetic species......, Recent advances in radiofrequency (RF) electronics have enabled the generation of pulses of the order of 10-50 ns. Such short pulses provide adequate spectral coverage for EPR studies at 300 MHz resonant frequency. Acquisition of free induction decays (FID) of paramagnetic species possessing...

  15. Determination of electronic properties of nanostructures using reflection electron energy loss spectroscopy: Nano-metalized polymer as case study

    Energy Technology Data Exchange (ETDEWEB)

    Deris, Jamileh [Department of Physics, Yasouj University, Yasouj 75918-74831 (Iran, Islamic Republic of); Hajati, Shaaker, E-mail: Hajati@mail.yu.ac.ir [Department of Physics, Yasouj University, Yasouj 75918-74831 (Iran, Islamic Republic of); Tougaard, Sven [Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, 5230 Odense M (Denmark); Zaporojtchenko, Vladimir [Lehrstuhl fur Materialverbunde, Technische Fakultat der CAU, Kaiserstr 2, D-24143 Kiel (Germany)

    2016-07-30

    Highlights: • Application of reflection electron energy loss spectroscopy. • Determination of electron inelastic cross section of Nano-metalized Polymer. • Determination of energy loss function of Nano-metalized Polymer. • Determination of electron inelastic mean free path of Nano-metalized Polymer. • Determination of surface excitation parameters of Nano-metalized Polymer. - Abstract: In this work, Au was deposited with nominal effective thickness of 0.8 nm on polystyrene (PS) at room temperature. According to previous study, using XPS peak shape analysis [S. Hajati, V. Zaporojtchenko, F. Faupel, S. Tougaard, Surf. Sci. 601 (2007) 3261–3267], Au nanoparticles (Au-NPs) of sizes 5.5 nm were formed corresponding to such effective thickness (0.8 nm). Then the sample was annealed to 200 °C, which is far above the glass transition of PS. At this temperature, the Au-NPs were diffused within the depth 0.5 nm–6.5 nm as found using nondestructive XPS peak shape analysis. Electrons with primary energy 500 eV were used because the electronic properties will then be probed in utmost surface (∼1 IMFP range of depths that is 1.8 nm for PS). By using QUEELS software, theoretical and experimental electron inelastic cross section, energy loss function, electron inelastic mean free path and surface excitation parameters were obtained for the sample. The information obtained here, does not rely on any previously known information on the sample. This means that the method, applied here, is suitable for the determination of the electronic properties of new and unknown composite nanostructures.

  16. Line shapes in inelastic electron tunneling spectroscopy of single-molecule junctions

    Science.gov (United States)

    Meierott, S.; Néel, N.; Kröger, J.

    2017-11-01

    Spectroscopic line-shape analyses for single-C60 vibrational modes are presented for two kinds of scanning tunneling microscope experiments. Inelastic electron tunneling spectroscopy is performed for C60 molecules with different adsorption geometries on Pb(111). Depending on the C60 adsorption site and rotational orientation, the lowest unoccupied molecular orbital exhibits varying degrees of overlap with C60 vibrational energies. Concomitantly, the line shapes of vibrational modes are affected according to expectations for on-resonance inelastic electron tunneling. Inelastic electron transport is further studied for decreasing tip-C60 distances covering tunneling and contact ranges. Line-shape changes signaling a conductance increase rather than the expected decrease upon exciting vibrational quanta are observed. A phenomenological approach is suggested to understand the dissimilar behavior of the junction conductance in the different electron transport ranges.

  17. Radiation damage to alkyl chain monolayers on semiconductor substrates investigated by electron spectroscopy.

    Science.gov (United States)

    Amy, Fabrice; Chan, Calvin K; Zhao, Wei; Hyung, Jaehyung; Ono, Masaki; Sueyoshi, Tomoki; Kera, Satoshi; Nesher, Guy; Salomon, Adi; Segev, Lior; Seitz, Oliver; Shpaisman, Hagay; Schöll, Achim; Haeming, Marc; Böcking, Till; Cahen, David; Kronik, Leeor; Ueno, Nobuo; Umbach, Eberhard; Kahn, Antoine

    2006-11-02

    Monolayers of alkyl chains, attached through direct Si-C bonds to Si(111), via phosphonates to GaAs(100) surfaces, or deposited as alkyl-silane monolayers on SiO2, are investigated by ultraviolet and inverse photoemission spectroscopy and X-ray absorption spectroscopy. Exposure to ultraviolet radiation from a He discharge lamp, or to a beam of energetic electrons, leads to significant damage, presumably associated with radiation- or electron-induced H-abstraction leading to carbon-carbon double-bond formation in the alkyl monolayer. The damage results in an overall distortion of the valence spectrum, in the appearance of (occupied) states above the highest occupied molecular orbital of the alkyl molecule, and in a characteristic (unoccupied state) pi resonance at the edge of the carbon absorption peak. These distortions present a serious challenge for the interpretation of the electronic structure of the monolayer system. We show that extrapolation to zero damage at short exposure times eliminates extrinsic features and allows a meaningful extraction of the density of state of the pristine monolayer from spectroscopy measurements.

  18. High-resolution electron spectroscopy of lanthanide (Ce, Pr, and Nd) complexes of cyclooctatetraene: the role of 4f electrons.

    Science.gov (United States)

    Kumari, Sudesh; Roudjane, Mourad; Hewage, Dilrukshi; Liu, Yang; Yang, Dong-Sheng

    2013-04-28

    Cerium, praseodymium, and neodymium complexes of 1,3,5,7-cyclooctatetraene (COT) complexes were produced in a laser-vaporization metal cluster source and studied by pulsed-field ionization zero electron kinetic energy spectroscopy and quantum chemical calculations. The computations included the second-order Møller-Plesset perturbation theory, the coupled cluster method with single, double, and perturbative triple excitations, and the state-average complete active space self-consistent field method. The spectrum of each complex exhibits multiple band systems and is assigned to ionization of several low-energy electronic states of the neutral complex. This observation is different from previous studies of M(COT) (M = Sc, Y, La, and Gd), for which a single band system was observed. The presence of the multiple low-energy electronic states is caused by the splitting of the partially filled lanthanide 4f orbitals in the ligand field, and the number of the low-energy states increases rapidly with increasing number of the metal 4f electrons. On the other hand, the 4f electrons have a small effect on the geometries and vibrational frequencies of these lanthanide complexes.

  19. Ultrafast XUV spectroscopy: Unveiling the nature of electronic couplings in molecular dynamics

    Science.gov (United States)

    Timmers, Henry Robert

    Molecules are traditionally treated quantum mechanically using the Born-Oppenheimer formalism. In this formalism, different electronic states of the molecule are treated independently. However, most photo-initiated phenomena occurring in nature are driven by the couplings between different electronic states in both isolated molecules and molecular aggregates, and therefore occur beyond the Born-Oppenheimer formalism. These couplings are relevant in reactions relating to the perception of vision in the human eye, the oxidative damage and repair of DNA, the harvesting of light in photosynthesis, and the transfer of charge across large chains of molecules. While these reaction dynamics have traditionally been studied with visible and ultraviolet spectroscopy, attosecond XUV pulses formed through the process of high harmonic generation form a perfect tool for probing coupled electronic dynamics in molecules. In this thesis, I will present our work in using ultrafast, XUV spectroscopy to study these dynamics in molecules of increasing complexity. We begin by probing the relaxation dynamics of superexcited states in diatomic O 2. These states can relax via two types of electronic couplings, either through autoionization or neutral dissociation. We find that our pump-probe scheme can disentangle the two relaxation mechanisms and independently measure their contributing lifetimes. Next, we present our work in observing a coherent electron hole wavepacket initiated by the ionization of polyatomic CO 2 near a conical intersection. The electron-nuclear couplings near the conical intersection drive the electron hole between different orbital configurations. We find that we can not only measure the lifetime of quantum coherence in the electron hole wavepacket, but also control its evolution with a strong, infrared probing field. Finally, we propose an experiment to observe the migration of an electron hole across iodobenzene on the few-femtosecond timescale. We present

  20. Instrumental development of a quasi-relativistic ultrashort electron beam source for electron diffractions and spectroscopies

    Science.gov (United States)

    Shin, Young-Min; Figora, Michael

    2017-10-01

    A stable femtosecond electron beam system has been configured for time-resolved pump-probe experiments. The ultrafast electron diffraction (UED) system is designed with a sub-MeV photoelectron beam source pulsed by a femtosecond UV laser and nondispersive beamline components, including a bunch compressor—a pulsed S-band klystron is installed and fully commissioned with 5.5 MW peak power in a 2.5 μs pulse length. A single-cell RF photo-gun is designed to produce 1.6-16 pC electron bunches in a photoemission mode with 150 fs pulse duration at 0.5-1 MeV. The measured RF system jitters are within 1% in magnitude and 0.2° in phase, which would induce 3.4 keV and 0.25 keV of ΔE, corresponding to 80 fs and 5 fs of Δt, respectively. Our particle-in-cell simulations indicate that the designed bunch compressor reduces the time-of-arrival jitter by about an order of magnitude. The transport and focusing optics of the designed beamline with the bunch compressor enables an energy spread within 10-4 and a bunch length (electron probe) within instrumental test results are presented along with the development of the quasi-relativistic UED system.

  1. Nanoscale probing of bandgap states on oxide particles using electron energy-loss spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Qianlang [School for the Engineering of Matter, Transport and Energy, Arizona State University, 85287 AZ (United States); March, Katia [Laboratoire de Physique des Solides, Bâtiment 510, Université Paris-Sud, 91405 Orsay Cedex (France); Crozier, Peter A., E-mail: CROZIER@asu.edu [School for the Engineering of Matter, Transport and Energy, Arizona State University, 85287 AZ (United States)

    2017-07-15

    Surface and near-surface electronic states were probed with nanometer spatial resolution in MgO and TiO{sub 2} anatase nanoparticles using ultra-high energy resolution electron energy-loss spectroscopy (EELS) coupled to a scanning transmission electron microscope (STEM). This combination allows the surface electronic structure determined with spectroscopy to be correlated with nanoparticle size, morphology, facet etc. By acquiring the spectra in aloof beam mode, radiation damage to the surface can be significantly reduced while maintaining the nanometer spatial resolution. MgO and TiO{sub 2} showed very different bandgap features associated with the surface/sub-surface layer of the nanoparticles. Spectral simulations based on dielectric theory and density of states models showed that a plateau feature found in the pre-bandgap region in the spectra from (100) surfaces of 60 nm MgO nanocubes is consistent with a thin hydroxide surface layer. The spectroscopy shows that this hydroxide species gives rise to a broad filled surface state at 1.1 eV above the MgO valence band. At the surfaces of TiO{sub 2} nanoparticles, pronounced peaks were observed in the bandgap region, which could not be well fitted to defect states. In this case, the high refractive index and large particle size may make Cherenkov or guided light modes the likely causes of the peaks. - Highlights: • Bandgap states detected with aloof beam monochromated EELS on oxide nanoparticle surfaces. • Dielectric theory applied to simulate the spectra and interpret surface structure. • Density of states models also be employed to understand the surface electronic structure. • In MgO, one states associate with water species was found close to the valence band edge. • In anatase, two mid-gap states associated with point defects were found.

  2. Monitoring of alcoholic fermentation using near infrared and mid infrared spectroscopies combined with electronic nose and electronic tongue.

    Science.gov (United States)

    Buratti, S; Ballabio, D; Giovanelli, G; Dominguez, C M Zuluanga; Moles, A; Benedetti, S; Sinelli, N

    2011-07-04

    Effective fermentation monitoring is a growing need due to the rapid pace of change in the wine industry, which calls for fast methods providing real time information in order to assure the quality of the final product. The objective of this work is to investigate the potential of non-destructive techniques associated with chemometric data analysis, to monitor time-related changes that occur during red wine fermentation. Eight micro-fermentation trials conducted in the Valtellina region (Northern Italy) during the 2009 vintage, were monitored by a FT-NIR and a FT-IR spectrometer and by an electronic nose and tongue. The spectroscopic technique was used to investigate molecular changes, while electronic nose and electronic tongue evaluated the evolution of the aroma and taste profile during the must-wine fermentation. Must-wine samples were also analysed by traditional chemical methods in order to determine sugars (glucose and fructose) consumption and alcohol (ethanol and glycerol) production. Principal Component Analysis was applied to spectral, electronic nose and electronic tongue data, as an exploratory tool, to uncover molecular, aroma and taste modifications during the fermentation process. Furthermore, the chemical data and the PC1 scores from spectral, electronic nose and electronic tongue data were modelled as a function of time to identify critical points during fermentation. The results showed that NIR and MIR spectroscopies are useful to investigate molecular changes involved in wine fermentation while electronic nose and electronic tongue can be applied to detect the evolution of taste and aroma profile. Moreover, as demonstrated through the modeling of NIR, MIR, electronic nose and electronic tongue data, these non destructive methods are suitable for the monitoring of must-wine fermentation giving crucial information about the quality of the final product in agreement with chemical parameters. Although in this study the measurements were carried out

  3. Spectroscopy

    DEFF Research Database (Denmark)

    Berg, Rolf W.

    This introductory booklet covers the basics of molecular spectroscopy, infrared and Raman methods, instrumental considerations, symmetry analysis of molecules, group theory and selection rules, as well as assignments of fundamental vibrational modes in molecules.......This introductory booklet covers the basics of molecular spectroscopy, infrared and Raman methods, instrumental considerations, symmetry analysis of molecules, group theory and selection rules, as well as assignments of fundamental vibrational modes in molecules....

  4. Determining binding energies of valence-band electrons in insulators and semiconductors via lanthanide spectroscopy

    Science.gov (United States)

    Dorenbos, Pieter

    2013-01-01

    Models and methods to determine the absolute binding energy of 4f-shell electrons in lanthanide dopants will be combined with data on the energy of electron transfer from the valence band to a lanthanide dopant. This work will show that it provides a powerful tool to determine the absolute binding energy of valence band electrons throughout the entire family of insulator and semiconductor compounds. The tool will be applied to 28 fluoride, oxide, and nitride compounds providing the work function and electron affinity together with the location of the energy levels of all divalent and all trivalent lanthanide dopants with an accuracy that surpasses that of traditional methods like photoelectron spectroscopy. The 28 compounds were selected to demonstrate how work function and electron affinity change with composition and structure, and how electronic structure affects the optical properties of the lanthanide dopants. Data covering more than 1000 different halide (F, Cl, Br, I), chalcogenide (O, S, Se), and nitride compounds are available in the archival literature enabling us to routinely establish work function and electron affinity for this much wider collection of compounds.

  5. Interest in broadband dielectric spectroscopy to study the electronic transport in materials for lithium batteries

    Energy Technology Data Exchange (ETDEWEB)

    Badot, Jean-Claude, E-mail: jc.badot@chimie-paristech.fr [Institut de Recherche de Chimie Paris, UMR CNRS 8247, Réseau sur le Stockage Electrochimique de l' Energie (RS2E), Chimie Paris Tech, PSL*, 11 rue P. et M. Curie, 75231 Cedex 05 Paris (France); Lestriez, Bernard [Institut des Matériaux Jean Rouxel, UMR CNRS 6502, Université de Nantes, 2 rue de la Houssinière, BP32229, 44322 Nantes (France); Dubrunfaut, Olivier [GeePs | Group of electrical engineering – Paris, UMR CNRS 8507, CentraleSupélec, Univ. Paris-Sud, Université Paris-Saclay, Sorbonne Universités, UPMC Univ Paris 06, 3 & 11 rue Joliot-Curie, Plateau de Moulon, 91192 Gif-sur-Yvette CEDEX, Paris (France)

    2016-11-15

    Highlights: • Broadband dielectric spectroscopy measures the multiscale electronic conductivity from macroscopic to interatomic sizes. • There is an influence of the surface states on the electronic transfer of powdered materials (e.g. thin insulating layer of Li{sub 2}CO{sub 3} on LiNiO{sub 2} and carbon coating on LiFePO{sub 4}). • Electrical relaxations resulting from the interfacial polarizations at the different scales of the carbon black network are evidenced. - Abstract: Broadband dielectric spectroscopy (BDS) is used to measure complex permittivity and conductivity of conducting materials for lithium batteries at frequencies from a few Hz to several GHz with network and impedance analysers. Under the influence of an electric field, there will be charge density fluctuations in the conductor mainly due to electronic transfer. These fluctuations result in dielectric relaxations for frequencies below 100 GHz. The materials are compacted powders in which each element (particles, agglomerates of particles) can have different sizes and morphologies. In the present review, studies are reported on the influence of surface states in LiNiO{sub 2} (ageing and degradation in air) and LiFePO{sub 4} (carbon coating thin layer), and on a composite electrode based on the lithium trivanadate (Li{sub 1.1}V{sub 3}O{sub 8}) active material. The results have shown that the BDS technique is very sensitive to the different scales of materials architectures involved in electronic transport, from interatomic distances to macroscopic sizes.

  6. Communication: Vibrational and vibronic coherences in the two dimensional spectroscopy of coupled electron-nuclear motion

    Energy Technology Data Exchange (ETDEWEB)

    Albert, Julian; Falge, Mirjam; Hildenbrand, Heiko; Engel, Volker [Universität Würzburg, Institut für Physikalische und Theoretische Chemie, Emil-Fischer-Str. 42, Campus Nord, Am Hubland, 97074 Würzburg (Germany); Gomez, Sandra; Sola, Ignacio R. [Departamento de Quimica Fisica, Universidad Complutense, 28040 Madrid (Spain)

    2015-07-28

    We theoretically investigate the photon-echo spectroscopy of coupled electron-nuclear quantum dynamics. Two situations are treated. In the first case, the Born-Oppenheimer (adiabatic) approximation holds. It is then possible to interpret the two-dimensional (2D) spectra in terms of vibrational motion taking place in different electronic states. In particular, pure vibrational coherences which are related to oscillations in the time-dependent third-order polarization can be identified. This concept fails in the second case, where strong non-adiabatic coupling leads to the breakdown of the Born-Oppenheimer-approximation. Then, the 2D-spectra reveal a complicated vibronic structure and vibrational coherences cannot be disentangled from the electronic motion.

  7. Some thoughts on source monochromation and the implications for electron energy loss spectroscopy

    CERN Document Server

    Brydson, R; Brown, A

    2003-01-01

    We briefly outline the factors determining the intrinsic widths of features in electron energy loss near edge structure (ELNES) measured by electron energy loss spectroscopy (EELS) in the transmission electron microscope (TEM). We have made estimates of the differing contributions of both the initial and final state lifetime effects in the ELNES ionisation processes and also show how these may be combined with the instrumental energy resolution. We discuss the potential benefits of source monochromation for ELNES measurements via a comparison of these theoretical estimates with experimental spectra from the literature. We show that for certain core level excitations, solid state broadening mechanisms may be the fundamental limiting factor for resolving fine detail in ELNES. (orig.)

  8. High resolution EUV spectroscopy of xenon ions with a compact electron beam ion trap

    Science.gov (United States)

    Ali, Safdar; Nakamura, Nobuyuki

    2017-09-01

    We performed high resolution extreme ultraviolet (EUV) spectroscopy measurements of highly charged xenon ions with a compact electron beam ion trap. The spectra were recorded with a flat-field grazing incidence spectrometer while varying the electron beam energy between 200 and 890 eV. We measured the wavelengths for several lines of Rh-like Xe9+ - Cd-like Xe6+ and Cu-like Xe25+- Se-like Xe20+ in the range of 150-200 Å with an uncertainty of 0.05 Å. Previously, most of these lines have been reported from EBITs with a wavelength uncertainty of 0.2 Å. Additionally, based on the electron beam energy dependence of the observed spectra we tentatively identified three new lines, which were reported as unidentified lines in the previous studies.

  9. Electron momentum spectroscopy of dimethyl ether taking account of nuclear dynamics in the electronic ground state

    Science.gov (United States)

    Morini, Filippo; Watanabe, Noboru; Kojima, Masataka; Deleuze, Michael Simon; Takahashi, Masahiko

    2015-10-01

    The influence of nuclear dynamics in the electronic ground state on the (e,2e) momentum profiles of dimethyl ether has been analyzed using the harmonic analytical quantum mechanical and Born-Oppenheimer molecular dynamics approaches. In spite of fundamental methodological differences, results obtained with both approaches consistently demonstrate that molecular vibrations in the electronic ground state have a most appreciable influence on the momentum profiles associated to the 2b1, 6a1, 4b2, and 1a2 orbitals. Taking this influence into account considerably improves the agreement between theoretical and newly obtained experimental momentum profiles, with improved statistical accuracy. Both approaches point out in particular the most appreciable role which is played by a few specific molecular vibrations of A1, B1, and B2 symmetries, which correspond to C-H stretching and H-C-H bending modes. In line with the Herzberg-Teller principle, the influence of these molecular vibrations on the computed momentum profiles can be unraveled from considerations on the symmetry characteristics of orbitals and their energy spacing.

  10. Probing new spin-independent interactions through precision spectroscopy in atoms with few electrons

    Science.gov (United States)

    Delaunay, Cédric; Frugiuele, Claudia; Fuchs, Elina; Soreq, Yotam

    2017-12-01

    The very high precision of current measurements and theory predictions of spectral lines in few-electron atoms allows us to efficiently probe the existence of exotic forces between electrons, neutrons and protons. We investigate the sensitivity to new spin-independent interactions in transition frequencies (and their isotopic shifts) of hydrogen, helium and some heliumlike ions. We find that present data probe new regions of the force-carrier couplings to electrons and neutrons around the MeV mass range. We also find that, below few keV, the sensitivity to the electron coupling in precision spectroscopy of helium and positronium is comparable to that of the anomalous magnetic moment of the electron. Finally, we interpret our results in the dark-photon model where a new gauge boson is kinetically mixed with the photon. There, we show that helium transitions, combined with the anomalous magnetic moment of the electron, provide the strongest indirect bound from laboratory experiments above 100 keV.

  11. Silicon drift detectors with on-chip electronics for x-ray spectroscopy.

    Science.gov (United States)

    Fiorini, C; Longoni, A; Hartmann, R; Lechner, P; Strüder, L

    1997-01-01

    The silicon drift detector (SDD) is a semiconductor device based on high resistivity silicon fully depleted through junctions implanted on both sides of the semiconductor wafer. The electrons generated by the ionizing radiation are driven by means of a suitable electric field from the point of interaction toward a collecting anode of small capacitance, independent of the active area of the detector. A suitably designed front-end JFET has been directly integrated on the detector chip close to the anode region, in order to obtain a nearly ideal capacitive matching between detector and transistor and to minimize the stray capacitances of the connections. This feature allows it to reach high energy resolution also at high count rates and near room temperature. The present work describes the structure and the performance of SDDs specially designed for high resolution spectroscopy with soft x rays at high detection rate. Experimental results of SDDs used in spectroscopy applications are also reported.

  12. Magnetic dynamics studied by high-resolution electron spectroscopy and time-resolved electron microscopy

    Science.gov (United States)

    Jayaraman, Rajeswari

    Future information technology requires an increased magnetically encoded data density and novel electromagnetic modes of data transfer. While to date magnetic properties are observed and characterized mostly statically, the need emerges to monitor and capture their fast dynamics. In this talk, I will focus on the spin dynamics i.e. spin wave excitations and the dynamics of a new topological distribution of spins termed ``skyrmions''. Wave packets of spin waves offer the unique capability to transport a quantum bit, the spin, without the transport of charge or mass. Here, large wave-vector spin waves are of particular interest as they admit spin localization within a few nanometers. By using our recently developed electron energy loss spectrometer, we could study such spin waves in ultrathin films with an unprecedented energy resolution of 4 meV. By virtue of the finite penetration depth of low energy electrons, spin waves localized at interfaces between a substrate and a thin capping layer can be been studied yielding information about the exchange coupling between atoms at the interface. The quantization of spin waves with wave vectors perpendicular to the film gives rise to standing modes to which EELS has likewise access. Such studies when carried out as function of the film thickness again yield information on the layer dependence of the exchange coupling. Magnetic skyrmions are promising candidates as information carriers in logic or storage devices. Currently, little is known about the influence of disorder, defects, or external stimuli on the spatial distribution and temporal evolution of the skyrmion lattice. In this talk, I will describe the dynamical role of disorder in a large and flat thin film of Cu2OSeO3, exhibiting a skyrmion phase in an insulating material. We image up to 70,000 skyrmions by means of cryo-Lorentz Transmission Electron Microscopy as a function of the applied magnetic field. In the skyrmion phase, dislocations are shown to cause the

  13. Investigation of Deuterium Implantation into Beryllium Sample by Electron Energy Loss Spectroscopy

    Science.gov (United States)

    Afanas’ev, V. P.; Gryazev, A. S.; Kaplya, P. S.; Köppen, M.; Ridzel, O. Yu; Subbotin, N. Yu; Hansen, P.

    2017-11-01

    Quantitative analysis of hydrogen isotopes in first wall as well as in construction materials of future fusion devices plays a crucial role to understand the evolution of those materials under operation conditions. A quantitative understanding of hydrogen in materials is also an important issue for storing energy as well as for fuel cells. A combination of Electron Energy Loss Spectroscopy (EELS) and Elastic Peak Electron Spectroscopy (EPES) is presented in this study to tackle these problems of modern material research for energy production and storage. Accurate inelastic scattering background subtraction is a key part of the presented quantitative measurement of the Be/D ratio. The differential inelastic scattering cross-section is determined by the fitting procedure. The fitting procedure is based on the iterative solution of the direct problem and minimization of the residual between computed and measured spectra. This study also takes into account the difference in electron energy loss laws for surface and bulk. The inelastic scattering cross-sections for different doses of deuterium ions in beryllium substrate (5.5·1021 m‑2 and 2.01·1022 m‑2) were defined in a two-layered model. The analysis is carried out for the EELS spectra. Relative concentration of D atoms is defined.

  14. Electronic states in vertically ordered Ge/Si quantum dots detected by photocurrent spectroscopy

    Science.gov (United States)

    Yakimov, A. I.; Kirienko, V. V.; Armbrister, V. A.; Bloshkin, A. A.; Dvurechenskii, A. V.

    2014-07-01

    We report on intraband photocurrent spectroscopy of sixfold stacked Ge/Si quantum dots embedded in a Si matrix and aligned along the growth direction. The dots are formed in a shape of pyramids with the average lateral size of 18 nm. The n-type heterostructures show broad spectral response ranging from 5 to 20 μm, depending on the polarization of the incoming infrared light. The normal incidence photocurrent peak centered around 12-15 μm is attributed to the transitions from the electron states localized in the Si region adjacent to the dots to continuum states of the Si matrix. The electron confinement is caused by a modification of the conduction band alignment induced by inhomogeneous tensile strain in Si around the buried Ge/Si quantum dots. Using the Ge content and dot shape determined by Raman and scanning tunneling microscopy analysis as input parameters for three-dimensional band structure simulations, a good agreement between measured and calculated electron binding energy is obtained. Photoluminescence spectroscopy and measurements of temperature dependence of dark conductance are used to correlate photocurrent results.

  15. High-Resolution Two-Dimensional Optical Spectroscopy of Electron Spins

    Directory of Open Access Journals (Sweden)

    M. Salewski

    2017-08-01

    Full Text Available Multidimensional coherent optical spectroscopy is one of the most powerful tools for investigating complex quantum mechanical systems. While it was conceived decades ago in magnetic resonance spectroscopy using microwaves and radio waves, it has recently been extended into the visible and UV spectral range. However, resolving MHz energy splittings with ultrashort laser pulses still remains a challenge. Here, we analyze two-dimensional Fourier spectra for resonant optical excitation of resident electrons to localized trions or donor-bound excitons in semiconductor nanostructures subject to a transverse magnetic field. Particular attention is devoted to Raman coherence spectra, which allow one to accurately evaluate tiny splittings of the electron ground state and to determine the relaxation times in the electron spin ensemble. A stimulated steplike Raman process induced by a sequence of two laser pulses creates a coherent superposition of the ground-state doublet which can be retrieved only optically because of selective excitation of the same subensemble with a third pulse. This provides the unique opportunity to distinguish between different complexes that are closely spaced in energy in an ensemble. The related experimental demonstration is based on photon-echo measurements in an n-type CdTe/(Cd,MgTe quantum-well structure detected by a heterodyne technique. The difference in the sub-μeV range between the Zeeman splittings of donor-bound electrons and electrons localized at potential fluctuations can be resolved even though the homogeneous linewidth of the optical transitions is larger by 2 orders of magnitude.

  16. REVIEW ARTICLE: On correlation effects in electron spectroscopies and the GW approximation

    Science.gov (United States)

    Hedin, Lars

    1999-10-01

    The GW approximation (GWA) extends the well-known Hartree-Fock approximation (HFA) for the self-energy (exchange potential), by replacing the bare Coulomb potential v by the dynamically screened potential W, e.g. Vex = iGv is replaced by icons/Journals/Common/Sigma" ALT="Sigma" ALIGN="TOP"/>GW = iGW. Here G is the one-electron Green's function. The GWA like the HFA is self-consistent, which allows for solutions beyond perturbation theory, like say spin-density waves. In a first approximation, iGW is a sum of a statically screened exchange potential plus a Coulomb hole (equal to the electrostatic energy associated with the charge pushed away around a given electron). The Coulomb hole part is larger in magnitude, but the two parts give comparable contributions to the dispersion of the quasi-particle energy. The GWA can be said to describe an electronic polaron (an electron surrounded by an electronic polarization cloud), which has great similarities to the ordinary polaron (an electron surrounded by a cloud of phonons). The dynamical screening adds new crucial features beyond the HFA. With the GWA not only bandstructures but also spectral functions can be calculated, as well as charge densities, momentum distributions, and total energies. We will discuss the ideas behind the GWA, and generalizations which are necessary to improve on the rather poor GWA satellite structures in the spectral functions. We will further extend the GWA approach to fully describe spectroscopies like photoemission, x-ray absorption, and electron scattering. Finally we will comment on the relation between the GWA and theories for strongly correlated electronic systems. In collecting the material for this review, a number of new results and perspectives became apparent, which have not been published elsewhere.

  17. Recent Developments of an Opto-Electronic THz Spectrometer for High-Resolution Spectroscopy

    Directory of Open Access Journals (Sweden)

    Guillaume Ducournau

    2009-11-01

    Full Text Available A review is provided of sources and detectors that can be employed in the THz range before the description of an opto-electronic source of monochromatic THz radiation. The realized spectrometer has been applied to gas phase spectroscopy. Air-broadening coefficients of HCN are determined and the insensitivity of this technique to aerosols is demonstrated by the analysis of cigarette smoke. A multiple pass sample cell has been used to obtain a sensitivity improvement allowing transitions of the volatile organic compounds to be observed. A solution to the frequency metrology is presented and promises to yield accurate molecular line center measurements.

  18. Development of 32-channel silicon drift detectors and digital electronics for X-ray spectroscopy.

    Science.gov (United States)

    Gauthier, C; Goujon, G; Goulon, J; Moguiline, E; Dressler, P; Henck, R; Lampert, M O

    1998-05-01

    The performance of silicon-drift-detector (SDD) arrays and digital electronics designed for X-ray absorption spectroscopy in the fluorescence excitation mode is reported. Different detectors have been manufactured and tested: two single-channel SDDs with different active areas (10 mm(2) and 1 cm(2)) and a monolithic 2 cm(2) SDD with eight readout anodes. The energy resolution varies between 160 and 170 eV FWHM. A new digital multichannel shaping amplifier has been produced. Its performance is presented in comparison with that of a standard commercial shaper.

  19. Femtosecond X-ray Absorption Spectroscopy at a Hard X-ray Free Electron Laser

    DEFF Research Database (Denmark)

    Lemke, Henrik T.; Bressler, Christian; Chen, Lin X.

    2013-01-01

    X-ray free electron lasers (XFELs) deliver short (hard X-rays, making them excellent sources for time-resolved studies. Here we show that, despite the inherent instabilities of current (SASE based) XFELs, they can be used for measuring high......-quality X-ray absorption data and we report femtosecond time-resolved X-ray absorption near-edge spectroscopy (XANES) measurements of a spin-crossover system, iron(II) tris(2,2'-bipyridine) in water. The data indicate that the low-spin to high-spin transition can be modeled by single-exponential kinetics...

  20. Gamma-irradiated ExtraVit M nutritive supplement studied by electron paramagnetic resonance spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Petrisor, Dina [Faculty of Physics, Babes-Bolyai University, 1A Kogalniceanu Street, 400084 Cluj-Napoca (Romania)], E-mail: dinapetrisor@yahoo.co.uk; Damian, Grigore; Simon, Simion [Faculty of Physics, Babes-Bolyai University, 1A Kogalniceanu Street, 400084 Cluj-Napoca (Romania)

    2008-04-15

    An unirradiated and {gamma}-irradiated nutritive supplement named ExtraVit M was studied by electron paramagnetic resonance (EPR) spectroscopy in order to detect stable paramagnetic species following improvement of hygienic quality by {gamma}-radiation. Free radicals were induced by {gamma}-radiation in the studied samples from low absorbed doses, showing a certain sensibility of these samples to the radiation treatment. The EPR spectrum of irradiated ExtraVit M is typical for drugs or nutritive supplements containing high levels of sugars, vitamin C and cellulose.

  1. Transient absorption spectroscopy of ultra-low band gap polymers for organic electronic applications

    Science.gov (United States)

    Fallon, Kealan J.; Dimitrov, Stoichko; Durrant, James; Bronstein, Hugo; Clarke, Tracey M.

    2016-09-01

    In this paper two extremely narrow band-gap polymers, based on naturally occurring indigo with high thin film crystallinity, have been examined using transient absorption spectroscopy. This was done in order to assess their charge photogeneration and recombination characteristics in blends with PC71BM. Two charge photogeneration mechanisms are found to be operating, depending on which component of the blend is photoexcited. Despite virtually isoenergetic LUMO levels, photoexcitation of the polymer causes standard electron transfer, albeit with a relatively low efficiency of 17 %. Photoexcitation of the fullerene, however, produces an exceptionally slow nanosecond timescale hole transfer.

  2. Measurement of electron paramagnetic resonance using terahertz time-domain spectroscopy.

    Science.gov (United States)

    Kozuki, Kohei; Nagashima, Takeshi; Hangyo, Masanori

    2011-12-05

    We present a frequency-domain electron spin resonance (ESR) measurement system using terahertz time-domain spectroscopy. A crossed polarizer technique is utilized to increase the sensitivity in detecting weak ESR signals of paramagnets caused by magnetic dipole transitions between magnetic sublevels. We demonstrate the measurements of ESR signal of paramagnetic copper(II) sulfate pentahydrate with uniaxial anisotropy of the g-factor under magnetic fields up to 10 T. The lineshape of the obtained ESR signals agrees well with the theoretical predictions for a powder sample with the uniaxial anisotropy.

  3. Phase-resolved optical emission spectroscopy for an electron cyclotron resonance etcher

    Energy Technology Data Exchange (ETDEWEB)

    Milosavljevic, Vladimir [BioPlasma Research Group, Dublin Institute of Technology, Sackville Place, Dublin 1 (Ireland); Biosystems Engineering, University College Dublin, Dublin 4, Ireland and Faculty of Physics, University of Belgrade, Belgrade (Serbia); MacGearailt, Niall; Daniels, Stephen; Turner, Miles M. [NCPST, Dublin City University, Dublin (Ireland); Cullen, P. J. [BioPlasma Research Group, Dublin Institute of Technology, Sackville Place, Dublin 1 (Ireland)

    2013-04-28

    Phase-resolved optical emission spectroscopy (PROES) is used for the measurement of plasma products in a typical industrial electron cyclotron resonance (ECR) plasma etcher. In this paper, the PROES of oxygen and argon atoms spectral lines are investigated over a wide range of process parameters. The PROES shows a discrimination between the plasma species from gas phase and those which come from the solid phase due to surface etching. The relationship between the micro-wave and radio-frequency generators for plasma creation in the ECR can be better understood by the use of PROES.

  4. Electroreflectance spectroscopy as a probe of the electronic structure at the metal-electronic interface

    Energy Technology Data Exchange (ETDEWEB)

    Ho, K.M.; Liu, S.H.

    1984-01-01

    The electromagnetic response of a surface is influenced by the surface electronic structure. In particular, the existence of surface states in band gaps can lead to optical absorption below the bulk interband threshold. However, such effects are usually too small to be observed because while surface states are localized within several atomic layers near the surface, light waves can penetrate at least hundreds of layers into the metal. One way to enhance the surface effect for a metallic surface is to make use of electromodulation techniques. When a metal is placed in an electrolyte, an intense electric field (approx. 10/sup 7/ volts/cm) can be induced at the metal-electrolyte boundary with the application of a bias voltage of less than a volt. Electroreflectance (ER) experiments modulate the bias voltage and measure the resultant modulations in the optical reflectivity. Since the static electric field is highly localized at the interface (the Fermi-Thomas screening length for typical metals is of the order of Angstroms) we expect the ER effect to be highly surface sensitive. Sensitivities in ..delta..R/R up to 10/sup -6/ can be achieved in such experiments. 12 references.

  5. The Pierre Auger Cosmic Ray Observatory

    Czech Academy of Sciences Publication Activity Database

    Aab, A.; Abreu, P.; Aglietta, M.; Boháčová, Martina; Chudoba, Jiří; Ebr, Jan; Grygar, Jiří; Mandát, Dušan; Nečesal, Petr; Palatka, Miroslav; Pech, Miroslav; Prouza, Michael; Řídký, Jan; Schovánek, Petr; Trávníček, Petr; Vícha, Jakub

    2015-01-01

    Roč. 798, Oct (2015), s. 172-213 ISSN 0168-9002 R&D Projects: GA MŠk(CZ) LG13007; GA MŠk(CZ) 7AMB14AR005; GA ČR(CZ) GA14-17501S Institutional support: RVO:68378271 Keywords : Pierre Auger Observatory * high energy cosmic rays * hybrid observatory * water Cherenkov detectors * air fluorescence detectors Subject RIV: BF - Elementary Particles and High Energy Physics Impact factor: 1.200, year: 2015

  6. Postcollision interactions in the Auger decay of the Ar L-shell

    Energy Technology Data Exchange (ETDEWEB)

    Samson, J.A.R.; Stolte, W.C.; He, Z.X. [Univ. of Nebraska, Lincoln, NE (United States)] [and others

    1997-04-01

    The photoionization cross sections for Ar{sup +} through Ar{sup 4+}, produced by the Auger decay of an inner shell 2p hole, have been measured between 242 eV and 253 eV on beamline 9.0.1 and 6.3.2. In this study the authors are interested in near threshold phenomenon involving postcollision interactions (PCI), which are related to the Auger decay of a vacancy in the Ar L-shell. During an Auger decay a postcollision interaction can occur causing the out-going photoelectron to be retarded thus losing a certain amount of energy. If the retardation is sufficiently large the photoelectron will not escape. This result produces a singly charged ion, which normally would not be present. Such evidence of electron capture by the PCI effect was first shown clearly by Eberhardt et al. and, with higher resolution, in the present work. However, capture of the photoelectron is expected to be 100% exactly at the L{sub 2,3} thresholds. Thus, from the authors results they would have expected the Ar{sup 2+} signal to be zero at threshold, but it was not? The authors can explain this anomoly on the basis that during the Auger decay the photoelectrons are captured into high lying excited states of Ar{sup +}, which subsequently decay through autoionization yielding Ar{sup 2+}. Future work in this area will seek experimental evidence to verify this prediction.

  7. Time-of-flight electron energy loss spectroscopy using TM110 deflection cavities

    Directory of Open Access Journals (Sweden)

    W. Verhoeven

    2016-09-01

    Full Text Available We demonstrate the use of two TM110 resonant cavities to generate ultrashort electron pulses and subsequently measure electron energy losses in a time-of-flight type of setup. The method utilizes two synchronized microwave cavities separated by a drift space of 1.45 m. The setup has an energy resolution of 12 ± 2 eV FWHM at 30 keV, with an upper limit for the temporal resolution of 2.7 ± 0.4 ps. Both the time and energy resolution are currently limited by the brightness of the tungsten filament electron gun used. Through simulations, it is shown that an energy resolution of 0.95 eV and a temporal resolution of 110 fs can be achieved using an electron gun with a higher brightness. With this, a new method is provided for time-resolved electron spectroscopy without the need for elaborate laser setups or expensive magnetic spectrometers.

  8. Non-equilibrium electron energy distribution in oxygen plasma: observation with optical emission spectroscopy

    Science.gov (United States)

    Boffard, John; Ly, Nathaniel; Wang, Shicong; Swee, Colin; Lin, Chun C.; Wendt, Amy

    2017-10-01

    Partially ionized inductively-coupled RF oxygen plasmas are in widespread use for materials processing, and non-invasive diagnostics are of interest for the optimization and control of the degrees of ionization and dissociation. Our initial study involves a 2-5% admixture of argon for optical emission spectroscopy (OES) of the oxygen plasma glow. The Ar 420.1/419.8 nm line intensity ratio, previously used in other mixtures to compute electron temperature, when 35 eV) electrons; the latter is observed under conditions of low power and high pressure in the oxygen plasma. We tentatively attribute the increase in energetic electrons to a transition to capacitive coupling, leading to electron acceleration to high energy in the sheaths adjacent to the powered electrode, which in this system is a spiral flat antenna separated from the plasma by a dielectric window. Investigations of OES methods involving additional species, including other trace rare gases, O, and O2+,to determine oxygen plasma properties such as non-Maxwellian electron energy distributions will also be described. Supported by NSF Grants PHY-1617602 and PHY-1068670.

  9. New Strategies for Atomic Scale Measurements at Interfaces using Electron Energy Loss Spectroscopy

    Science.gov (United States)

    Muller, David A.

    1997-03-01

    The local electronic structure of a material can be measured directly from the energy loss spectrum of a swift electron scattered through it. When the electron beam is focussed down to the width of an atomic column, the electronic density of states at an interface, grain boundary or impurity site can be decomposed by site, chemical species and angular momentum. Here, we discuss the use of electron energy loss spectroscopy (EELS) fine structure to provide insight into the origin of grain boundary and interfacial properties. EELS can reveal the physics underlying why a particular local bonding arrangement develops. Even a qualitative understanding of local bonding can help indentify possible sites for chemical reactions and potentially weak points at a grain boundary. More can be done however: an EELS sum rule allows quantitative estimates of grain boundary energies. This is particularly useful at general, large angle grain boundaries where no other atomic scale information can be obtained. As an example, we show how atomic-scale EELS measurements of grain boundaries in Ni_3Al (D.A. Muller, S. Subramanian, P.E. Batson, S.L. Sass, J. Silcox, Phys. Rev. Lett.) 75 4744 (1995). lead not only to rules-of-thumb for segregation and bond strength, but also to quantitative estimates of the boundary cohesion. Application to magnetic multilayers and Al:Cu interconnects will also be touched on. (Work at Cornell supported by DOE grant DE-FG02-87ER45322 and NSF grant DMR-9121654.)

  10. Distributed Computing for the Pierre Auger Observatory

    Science.gov (United States)

    Chudoba, J.

    2015-12-01

    Pierre Auger Observatory operates the largest system of detectors for ultra-high energy cosmic ray measurements. Comparison of theoretical models of interactions with recorded data requires thousands of computing cores for Monte Carlo simulations. Since 2007 distributed resources connected via EGI grid are successfully used. The first and the second versions of production system based on bash scripts and MySQL database were able to submit jobs to all reliable sites supporting Virtual Organization auger. For many years VO auger belongs to top ten of EGI users based on the total used computing time. Migration of the production system to DIRAC interware started in 2014. Pilot jobs improve efficiency of computing jobs and eliminate problems with small and less reliable sites used for the bulk production. The new system has also possibility to use available resources in clouds. Dirac File Catalog replaced LFC for new files, which are organized in datasets defined via metadata. CVMFS is used for software distribution since 2014. In the presentation we give a comparison of the old and the new production system and report the experience on migrating to the new system.

  11. Inelastic electron tunneling spectroscopy of difurylethene-based photochromic single-molecule junctions.

    Science.gov (United States)

    Kim, Youngsang; Bahoosh, Safa G; Sysoiev, Dmytro; Huhn, Thomas; Pauly, Fabian; Scheer, Elke

    2017-01-01

    Diarylethene-derived molecules alter their electronic structure upon transformation between the open and closed forms of the diarylethene core, when exposed to ultraviolet (UV) or visible light. This transformation results in a significant variation of electrical conductance and vibrational properties of corresponding molecular junctions. We report here a combined experimental and theoretical analysis of charge transport through diarylethene-derived single-molecule devices, which are created using the mechanically controlled break-junction technique. Inelastic electron tunneling (IET) spectroscopy measurements performed at 4.2 K are compared with first-principles calculations in the two distinct forms of diarylethenes connected to gold electrodes. The combined approach clearly demonstrates that the IET spectra of single-molecule junctions show specific vibrational features that can be used to identify different isomeric molecular states by transport experiments.

  12. Electron Temperature Measurement of Buried Layer Targets Using Time Resolved K-shell Spectroscopy

    Science.gov (United States)

    Marley, Edward; Foord, M. E.; Shepherd, R.; Beiersdorfer, P.; Brown, G.; Chen, H.; Emig, J.; Schneider, M.; Widmann, K.; Scott, H.; London, R.; Martin, M.; Wilson, B.; Iglesias, C.; Mauche, C.; Whitley, H.; Nilsen, J.; Hoarty, D.; James, S.; Brown, C. R. D.; Hill, M.; Allan, P.; Hobbs, L.

    2016-10-01

    Short pulse laser-heated buried layer experiments have been performed with the goal of creating plasmas with mass densities >= 1 g/cm3 and electron temperatures >= 500 eV. The buried layer geometry has the advantage of rapid energy deposition before significant hydrodynamic expansion occurs. For brief periods (< 40 ps) this provides a low gradient, high density platform for studying emission characteristics under extreme plasma conditions. A study of plasma conditions achievable using the Orion laser facility has been performed. Time resolved K-shell spectroscopy was used to determine the temperature evolution of buried layer aluminum foil targets. The measured evolution is compared to a 2-D PIC simulation done using LSP, which shows late time heating from the non-thermal electron population. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  13. Electron energy loss spectroscopy of excitons in two-dimensional-semiconductors as a function of temperature

    KAUST Repository

    Tizei, Luiz H. G.

    2016-04-21

    We have explored the benefits of performing monochromated Electron Energy Loss Spectroscopy(EELS) in samples at cryogenic temperatures. As an example, we have observed the excitonic absorption peaks in single layer Transition Metal Dichalcogenides. These peaks appear separated by small energies due to spin orbit coupling. We have been able to distinguish the split for MoS2 below 300 K and for MoSe2 below 220 K. However, the distinction between peaks is only clear at 150 K. We have measured the change in absorption threshold between 150 K and 770 K for MoS2 and MoSe2. We discuss the effect of carbon and ice contamination in EELSspectra. The increased spectral resolution available made possible with modern monochromators in electron microscopes will require the development of stable sample holders which reaches temperatures far below that of liquid nitrogen.

  14. Characterization of humic acids from tundra soils of northern Western Siberia by electron paramagnetic resonance spectroscopy

    Science.gov (United States)

    Chukov, S. N.; Ejarque, E.; Abakumov, E. V.

    2017-01-01

    Humic acids from polar soils—cryozems (Cryosols), gleyezems (Gleysols), and peat soils (Histosols)—have been studied by electron paramagnetic resonance spectroscopy. First information was acquired on the content of free radicals in humic acids from polar soils for the northern regions of Western Siberia (Gydan Peninsula, Belyi Island). It was found that polar soils are characterized by higher contents of free radicals than other zonal soils. This is related to the lower degree of humification of organic matter and the enhanced hydromorphism under continuous permafrost conditions. The low degree of organic matter humification in the cryolithozone was confirmed by the increased content of free radicals as determined by electron paramagnetic resonance, which indicates a low biothermodynamic stability of organic matter.

  15. Reduced electron exposure for energy-dispersive spectroscopy using dynamic sampling

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yan; Godaliyadda, G. M. Dilshan; Ferrier, Nicola; Gulsoy, Emine B.; Bouman, Charles A.; Phatak, Charudatta

    2018-01-01

    Analytical electron microscopy and spectroscopy of biological specimens, polymers, and other beam sensitive materials has been a challenging area due to irradiation damage. There is a pressing need to develop novel imaging and spectroscopic imaging methods that will minimize such sample damage as well as reduce the data acquisition time. The latter is useful for high-throughput analysis of materials structure and chemistry. In this work, we present a novel machine learning based method for dynamic sparse sampling of EDS data using a scanning electron microscope. Our method, based on the supervised learning approach for dynamic sampling algorithm and neural networks based classification of EDS data, allows a dramatic reduction in the total sampling of up to 90%, while maintaining the fidelity of the reconstructed elemental maps and spectroscopic data. We believe this approach will enable imaging and elemental mapping of materials that would otherwise be inaccessible to these analysis techniques.

  16. Lightning Detection at the Pierre-Auger-Observatory

    OpenAIRE

    Niemietz, Lukas

    2017-01-01

    The Pierre Auger Observatory in Argentina is the world largest detector for cosmic rays at the highest energies. It is realized as a hybrid detector, combining the detection of secondary particles at ground level with an array of 1660 water-Cherenkov detectors deployed over an area of about 3000 km² and the detection of emitted florescence light with 27 florescence telescopes at four sites around the array. For the Auger Engineering Radio Array, an extension of the Pierre Auger Observator...

  17. The SPEDE Spectrometer: Combined In-Beam γ-ray and Conversion Electron Spectroscopy with Radioactive Ion Beams

    Science.gov (United States)

    Papadakis, Philippos; Pakarinen, Janne; Butler, Peter A.; Cox, Daniel M.; Davies, Paul; Greenlees, Paul; Herzberg, Rolf-Dietmar; Huyse, Mark; Jenkins, David G.; Konki, Joonas; O'Neill, George G.; Rahkila, Panu; Ranttila, Kimmo; Saarela, Ville-Peka; Thornhill, Jim; Van Duppen, Piet; Wells, David

    The SPEDE conversion electron spectrometer will be combined with the Miniball germanium detector array for combined in-beam electron and γ-ray spectroscopy with radioactive ion beams. SPEDE will be primarily employed in Coulomb excitation experiments at HIE-ISOLDE, CERN.

  18. Two-photon laser spectroscopy of antiprotonic helium and the antiproton-to-electron mass ratio

    CERN Document Server

    Hori, Masaki; Barna, Daniel; Andreas Dax,; Hayano, Ryugo; Friedreich, Susanne; Juhász, Bertalan; Pask, Thomas; Widmann, Eberhard; Horváth, Dezső; Venturelli, Luca; Zurlo, Nicola; 10.1038/nature10260

    2013-01-01

    Physical laws are believed to be invariant under the combined transformations of charge, parity and time reversal (CPT symmetry). This implies that an antimatter particle has exactly the same mass and absolute value of charge as its particle counterpart. Metastable antiprotonic helium ($\\bar{p}He^+$) is a three-body atom2 consisting of a normal helium nucleus, an electron in its ground state and an antiproton ($\\bar{p}$) occupying a Rydberg state with high principal and angular momentum quantum numbers, respectively n and l, such that n ≈ l + 1 ≈ 38. These atoms are amenable to precision laser spectroscopy, the results of which can in principle be used to determine the antiproton-to-electron mass ratio and to constrain the equality between the antiproton and proton charges and masses. Here we report two-photon spectroscopy of antiprotonic helium, in which $\\bar{p}^{3}He^{+}$ and $\\bar{p}^{4}He^{+}$ isotopes are irradiated by two counter-propagating laser beams. This excites nonlinear, two-phot...

  19. Reflection electron energy loss spectroscopy of nanometric oxide layers and of their interfaces with a substrate

    Energy Technology Data Exchange (ETDEWEB)

    Paumier, Fabien [Service de Physique de Chimie des Surfaces et des Interfaces, DSM/DRECAM/SPCSI, CEA Saclay, 91191 Gif sur Yvette Cedex (France) and Laboratoire de Metallurgie Physique-UMR 6630 CNRS, Department of Materials Sciences, University of Poitiers (France)]. E-mail: fabien.paumier@univ-poitiers.fr; Fouquet, Valerie [Service de Physique de Chimie des Surfaces et des Interfaces, DSM/DRECAM/SPCSI, CEA Saclay, 91191 Gif sur Yvette Cedex (France); Guittet, Marie-Jo [Service de Physique de Chimie des Surfaces et des Interfaces, DSM/DRECAM/SPCSI, CEA Saclay, 91191 Gif sur Yvette Cedex (France); Gautier-Soyer, Martine [Service de Physique de Chimie des Surfaces et des Interfaces, DSM/DRECAM/SPCSI, CEA Saclay, 91191 Gif sur Yvette Cedex (France); French, Roger H. [Department of Materials Science and Engineering, University of Pennsylvania, 3231 Walnut Street, Philadelphia, PA 19104 (United States); DuPont Central Research, E356-384 Experimental Station, Wilmington, DE 19880 (United States); Tan Guolong [Department of Materials Science and Engineering, University of Pennsylvania, 3231 Walnut Street, Philadelphia, PA 19104 (United States); Chiang, Yet Ming [Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA (United States); Tang Ming [Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA (United States); Ramos, Ana [Service de Physique de Chimie des Surfaces et des Interfaces, DSM/DRECAM/SPCSI, CEA Saclay, 91191 Gif sur Yvette Cedex (France); Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA (United States); Chung, Sung-Yoon [Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA (United States)

    2006-04-25

    The aim of the present work was to evaluate the ability of reflection electron energy loss spectroscopy (REELS) as a non-destructive method to obtain depth profiles of dielectric constants, in a complementary way to transmission electron energy loss spectroscopy (TEELS). Two prototypical samples were used: a SrTiO{sub 3} single crystal and a 2 nm thick SiO{sub 2} layer on a Si single crystal. The single scattering cross-sections were decomposed into bulk, surface and interface contributions, with Drude-Lorentz parameters of the dielectric function fitted on available optical or TEELS data. We show that the evolution of the shape of the REELS single scattering cross-section with primary energy is qualitatively well reproduced by our model. In the case of the 2 nm SiO{sub 2} layer on Si, introducing the Si/SiO{sub 2} interface energy loss function contribution proved necessary to account for the interface plasmon peak observed, in very good agreement with reported TEELS measurements. REELS is well suited to studying dielectric properties of interfaces between a substrate and a nanometric layer.

  20. A microwave resonator for limiting depth sensitivity for electron paramagnetic resonance spectroscopy of surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Sidabras, Jason W.; Varanasi, Shiv K.; Hyde, James S. [Department of Biophysics, Medical College of Wisconsin, Milwaukee, Wisconsin 53211 (United States); Mett, Richard R. [Department of Biophysics, Medical College of Wisconsin, Milwaukee, Wisconsin 53211 (United States); Department of Physics and Chemistry, Milwaukee School of Engineering, Milwaukee, Wisconsin 53202 (United States); Swarts, Steven G. [Department of Radiation Oncology, University of Florida, Gainesville, Florida, 32610 (United States); Swartz, Harold M. [Department of Radiology, Geisel Medical School at Dartmouth, Hanover, New Hampshire 03755 (United States)

    2014-10-15

    A microwave Surface Resonator Array (SRA) structure is described for use in Electron Paramagnetic Resonance (EPR) spectroscopy. The SRA has a series of anti-parallel transmission line modes that provides a region of sensitivity equal to the cross-sectional area times its depth sensitivity, which is approximately half the distance between the transmission line centers. It is shown that the quarter-wave twin-lead transmission line can be a useful element for design of microwave resonators at frequencies as high as 10 GHz. The SRA geometry is presented as a novel resonator for use in surface spectroscopy where the region of interest is either surrounded by lossy material, or the spectroscopist wishes to minimize signal from surrounding materials. One such application is in vivo spectroscopy of human finger-nails at X-band (9.5 GHz) to measure ionizing radiation dosages. In order to reduce losses associated with tissues beneath the nail that yield no EPR signal, the SRA structure is designed to limit depth sensitivity to the thickness of the fingernail. Another application, due to the resonator geometry and limited depth penetration, is surface spectroscopy in coating or material science. To test this application, a spectrum of 1.44 μM of Mg{sup 2+} doped polystyrene 1.1 mm thick on an aluminum surface is obtained. Modeling, design, and simulations were performed using Wolfram Mathematica (Champaign, IL; v. 9.0) and Ansys High Frequency Structure Simulator (HFSS; Canonsburg, PA; v. 15.0). A micro-strip coupling circuit is designed to suppress unwanted modes and provide a balanced impedance transformation to a 50 Ω coaxial input. Agreement between simulated and experimental results is shown.

  1. A microwave resonator for limiting depth sensitivity for electron paramagnetic resonance spectroscopy of surfaces.

    Science.gov (United States)

    Sidabras, Jason W; Varanasi, Shiv K; Mett, Richard R; Swarts, Steven G; Swartz, Harold M; Hyde, James S

    2014-10-01

    A microwave Surface Resonator Array (SRA) structure is described for use in Electron Paramagnetic Resonance (EPR) spectroscopy. The SRA has a series of anti-parallel transmission line modes that provides a region of sensitivity equal to the cross-sectional area times its depth sensitivity, which is approximately half the distance between the transmission line centers. It is shown that the quarter-wave twin-lead transmission line can be a useful element for design of microwave resonators at frequencies as high as 10 GHz. The SRA geometry is presented as a novel resonator for use in surface spectroscopy where the region of interest is either surrounded by lossy material, or the spectroscopist wishes to minimize signal from surrounding materials. One such application is in vivo spectroscopy of human finger-nails at X-band (9.5 GHz) to measure ionizing radiation dosages. In order to reduce losses associated with tissues beneath the nail that yield no EPR signal, the SRA structure is designed to limit depth sensitivity to the thickness of the fingernail. Another application, due to the resonator geometry and limited depth penetration, is surface spectroscopy in coating or material science. To test this application, a spectrum of 1.44 μM of Mg(2+) doped polystyrene 1.1 mm thick on an aluminum surface is obtained. Modeling, design, and simulations were performed using Wolfram Mathematica (Champaign, IL; v. 9.0) and Ansys High Frequency Structure Simulator (HFSS; Canonsburg, PA; v. 15.0). A micro-strip coupling circuit is designed to suppress unwanted modes and provide a balanced impedance transformation to a 50 Ω coaxial input. Agreement between simulated and experimental results is shown.

  2. Dosimetry assessment of DNA damage by Auger-emitting radionuclides: Experimental and Monte Carlo studies

    Science.gov (United States)

    Di Maria, S.; Belchior, A.; Pereira, E.; Quental, L.; Oliveira, M. C.; Mendes, F.; Lavrado, J.; Paulo, A.; Vaz, P.

    2017-11-01

    Recently there has been considerable effort to investigate the potential use and efficacy of Auger-electron emitters in targeted radiotherapy. Auger electrons travel a short distance within human tissues (at nano-scale level) and, therefore, if an Auger-emitting radionuclide is transported to the cell nucleus it will cause enhanced DNA damage. Among the Auger-emitting radionuclides, 125I is of particular interest, as it emits about 25 electrons per decay. 99mTc only emits 5 electrons per decay, but presents some attractive characteristics such as a short half-life, easy procurement and availability and ideal imaging properties for therapy monitoring. In order to study the dosimetric behavior of these two radionuclides (125I and 99mTc) at nano-scale sizes and given the DNA-intercalation properties of Acridine Orange (AO), we have designed 99mTc (I)-tricarbonyl complexes and 125I-heteroaromatic compounds that contain AO derivatives, in order to promote a closer proximity between the radionuclides and the DNA structure. With the aim to have an insight on the relevance of these radiolabelled compounds for DNA-targeted Auger therapy, different aspects were investigated: i) their ability to cause DNA strand breaks; ii) the influence of the two different radionuclides in DNA damage; iii) the effect of the distance between the AO intercalating unit and the radioactive atom (99mTc or 125I). To address these issues several studies were carried out encompassing the evaluation of plasmid DNA damage, molecular docking and nanodosimetric Monte Carlo modelling and calculations. Results show that the two classes of compounds are able to induce DNA double strand breaks (dsb), but the number of DNA damages (e.g. dsb yield) is strongly dependent on the linker used to attach the Auger emitting radionuclide (125I or 99mTc) to the AO moiety. In addition, nanodosimetric calculations confirm a strong gradient of the absorbed energy with the DNA-radionuclide distance for the two

  3. Electronic structure of advanced materials studied by x-ray emission spectroscopy

    Science.gov (United States)

    Kurmaev, E. Z.; Galakhov, V. R.; Yarmoshenko, Yu. M.; Trofimova, V. A.; Shamin, S. N.; Cherkashenko, V. M.; Poteryaev, A. I.; Anisimov, V. I.

    1997-01-01

    High resolution soft x-ray emission spectroscopy with high spatial resolution is used to study of the electronic structure and characterize advanced materials: high-Tc superconductors, transition metal compounds, porous silicon, solid-solid buried interfaces and hard materials. In high-Tc, the main attention is focused on the analysis of oxygen-cation interactions and the determination of the location of impurity atoms. In transition metal compounds the participation of different electronic states of constitute atoms in the valence band is analyzed and correctness of LDA band structure calculations is estimated. For CuFeO2 an unusual mutual position of the Cu3d and Fe3d bands was found which is attributed to strong electron-electron correlations. In porous silicon the local structure of silicon atoms is found to depend on the type of doping of the initial Si wafer. Solid-solid buried interfaces in thin semiconducting films irradiated by eximer laser are investigated. For the hard materials boron-carbonitride a structure consisting of hexagonal lattice planes of carbon and boron nitride is proposed.

  4. Use of nonlocal helium microplasma for gas impurities detection by the collisional electron spectroscopy method

    Energy Technology Data Exchange (ETDEWEB)

    Kudryavtsev, Anatoly A., E-mail: akud@ak2138.spb.edu [St. Petersburg State University, 7-9 Universitetskaya nab., 199034 St. Petersburg (Russian Federation); Stefanova, Margarita S.; Pramatarov, Petko M. [Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussee blvd., 1784 Sofia (Bulgaria)

    2015-10-15

    The collisional electron spectroscopy (CES) method, which lays the ground for a new field for analytical detection of gas impurities at high pressures, has been verified. The CES method enables the identification of gas impurities in the collisional mode of electron movement, where the advantages of nonlocal formation of the electron energy distribution function (EEDF) are fulfilled. Important features of dc negative glow microplasma and probe method for plasma diagnostics are applied. A new microplasma gas analyzer design is proposed. Admixtures of 0.2% Ar, 0.6% Kr, 0.1% N{sub 2}, and 0.05% CO{sub 2} are used as examples of atomic and molecular impurities to prove the possibility for detecting and identifying their presence in high pressure He plasma (50–250 Torr). The identification of the particles under analysis is made from the measurements of the high energy part of the EEDF, where maxima appear, resulting from the characteristic electrons released in Penning reactions of He metastable atoms with impurity particles. Considerable progress in the development of a novel miniature gas analyzer for chemical sensing in gas phase environments has been made.

  5. Electron spectroscopy, molecular structures, and binding energies of Al- and Cu-imidazole.

    Science.gov (United States)

    Wang, Xu; Lee, Jung Sup; Yang, Dong-Sheng

    2006-11-30

    Al- and Cu-imidazole are produced in laser-vaporization supersonic molecular beams and studied with pulsed field ionization-zero electron kinetic energy (ZEKE) spectroscopy and second-order Møller-Plesset (MP2) theory. The sigma and pi structures of these complexes are predicted by MP2 calculations, but only the sigma structures are identified by the experimental measurements. For these sigma structures, adiabatic ionization energies and several vibrational frequencies are measured from the ZEKE spectra, the ground electronic states of the neutral and ionized complexes are determined by comparing the observed and calculated spectra, and the metal-ligand bond dissociation energies of the neutral states are derived by using a thermochemical relation. The measured vibrational modes include the metal-ligand stretch and bend and ligand ring distortions. The metal-ligand stretch frequencies of these transient complexes are compared with those of coordinately saturated, stable metal compounds, and the ligand-based distortion frequencies are compared with those of the free ligand. Al-imidazole has a larger bond dissociation energy than Cu-imidazole, although the opposite order was previously found for the corresponding ions. The weaker bonding of the Cu complex is attributed to the antibonding interaction and the electron repulsion between the Cu 4s and N lone-pair electrons.

  6. Analyzing Xanthine Dehydrogenase Iron-Sulfur Clusters Using Electron Paramagnetic Resonance Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Hodson, R.

    2004-02-05

    Xanthine dehydrogenase is a metalloenzyme that is present in a variety of eukaryotic and prokaryotic organisms. The oxidation of the xanthine occurs at the molybdenum site, and the catalytic cycle is completed by electron transfer to the iron-sulfur (Fe/S) clusters and finally the flavin, where they are accepted by nicotinamide adenine dinucleotide (NAD). Since the site giving rise to the Fe/S I electron paramagnetic resonance (EPR) signal is thought to be the initial recipient of the electrons from the Mo, we wish to understand which EPR signal is associated with which Fe/S cluster in the structure in order to develop an understanding of the electron flow within the molecule. Samples of xanthine dehydrogenase wild-type and mutant forms were analyzed with EPR spectroscopy techniques at low and high temperatures. The results showed an altered Fe/S I signal along with an unaltered Fe/S II signal. The converted Cysteine, in the mutant, did affect the Fe/S cluster immediately adjacent to it. Therefore, the Fe/S I signal arises from the Fe/S cluster closest to the Mo and immediately adjacent to the mutated amino acid, and the Fe/S II signal must arise from the more distant Fe/S cluster.

  7. High-Resolution Electron Energy-Loss Spectroscopy (HREELS) Using a Monochromated TEM/STEM

    Science.gov (United States)

    Sai, Z. R.; Bradley, J. P.; Erni, R.; Browning, N.

    2005-01-01

    A 200 keV FEI TF20 XT monochromated (scanning) transmission electron microscope funded by NASA's SRLIDAP program is undergoing installation at Lawrence Livermore National Laboratory. Instrument specifications in STEM mode are Cs =1.0 mm, Cc =1.2 mm, image resolution =0.18 nm, and in TEM mode Cs =1.3 mm, Cc =1.3 mm, information limit =0.14 nm. Key features of the instrument are a voltage-stabilized high tension (HT) supply, a monochromator, a high-resolution electron energy-loss spectrometer/energy filter, a high-resolution annular darkfield detector, and a solid-state x-ray energy-dispersive spectrometer. The high-tension tank contains additional sections for 60Hz and high frequency filtering, resulting in an operating voltage of 200 kV plus or minus 0.005V, a greater than 10-fold improvement over earlier systems. The monochromator is a single Wien filter design. The energy filter is a Gatan model 866 Tridiem-ERS high resolution GIF spec d for less than or equal to 0.15 eV energy resolution with 29 pA of current in a 2 nm diameter probe. 0.13 eV has already been achieved during early installation. The x-ray detector (EDAX/Genesis 4000) has a take-off angle of 20 degrees, an active area of 30 square millimeters, and a solid angle of 0.3 steradians. The higher solid angle is possible because the objective pole-piece allows the detector to be positioned as close as 9.47 mm from the specimen. The voltage-stabilized HT supply, monochromator and GIF enable high-resolution electron energy-loss spectroscopy (HREELS) with energy resolution comparable to synchrotron XANES, but with approximately 100X better spatial resolution. The region between 0 and 100 eV is called the low-loss or valence electron energy-loss spectroscopy (VEELS) region where features due to collective plasma oscillations and single electron transitions of valence electrons are observed. Most of the low-loss VEELS features we are detecting are being observed for the first time in IDPs. A major focus of

  8. Suppressed blinking and auger recombination in near-infrared type-II InP/CdS nanocrystal quantum dots.

    Science.gov (United States)

    Dennis, Allison M; Mangum, Benjamin D; Piryatinski, Andrei; Park, Young-Shin; Hannah, Daniel C; Casson, Joanna L; Williams, Darrick J; Schaller, Richard D; Htoon, Han; Hollingsworth, Jennifer A

    2012-11-14

    Nonblinking excitonic emission from near-infrared and type-II nanocrystal quantum dots (NQDs) is reported for the first time. To realize this unusual degree of stability at the single-dot level, novel InP/CdS core/shell NQDs were synthesized for a range of shell thicknesses (~1-11 monolayers of CdS). Ensemble spectroscopy measurements (photoluminescence peak position and radiative lifetimes) and electronic structure calculations established the transition from type-I to type-II band alignment in these heterostructured NQDs. More significantly, single-NQD studies revealed clear evidence for blinking suppression that was not strongly shell-thickness dependent, while photobleaching and biexciton lifetimes trended explicitly with extent of shelling. Specifically, very long biexciton lifetimes-up to >7 ns-were obtained for the thickest-shell structures, indicating dramatic suppression of nonradiative Auger recombination. This new system demonstrates that electronic structure and shell thickness can be employed together to effect control over key single-dot and ensemble NQD photophysical properties.

  9. A method for the direct measurement of electronic site populations in a molecular aggregate using two-dimensional electronic-vibrational spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Lewis, Nicholas H. C. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Dong, Hui [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Oliver, Thomas A. A. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Fleming, Graham R. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2015-09-28

    Two dimensional electronic spectroscopy has proven to be a valuable experimental technique to reveal electronic excitation dynamics in photosynthetic pigment-protein complexes, nanoscale semiconductors, organic photovoltaic materials, and many other types of systems. It does not, however, provide direct information concerning the spatial structure and dynamics of excitons. 2D infrared spectroscopy has become a widely used tool for studying structural dynamics but is incapable of directly providing information concerning electronic excited states. 2D electronic-vibrational (2DEV) spectroscopy provides a link between these domains, directly connecting the electronic excitation with the vibrational structure of the system under study. In this work, we derive response functions for the 2DEV spectrum of a molecular dimer and propose a method by which 2DEV spectra could be used to directly measure the electronic site populations as a function of time following the initial electronic excitation. We present results from the response function simulations which show that our proposed approach is substantially valid. This method provides, to our knowledge, the first direct experimental method for measuring the electronic excited state dynamics in the spatial domain, on the molecular scale.

  10. A method for the direct measurement of electronic site populations in a molecular aggregate using two-dimensional electronic-vibrational spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Lewis, Nicholas H. C.; Dong, Hui; Oliver, Thomas A. A.; Fleming, Graham R., E-mail: grfleming@lbl.gov [Department of Chemistry, University of California, Berkeley, California 94720 (United States); Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Kavli Energy Nanosciences Institute at Berkeley, Berkeley, California 94720 (United States)

    2015-09-28

    Two dimensional electronic spectroscopy has proved to be a valuable experimental technique to reveal electronic excitation dynamics in photosynthetic pigment-protein complexes, nanoscale semiconductors, organic photovoltaic materials, and many other types of systems. It does not, however, provide direct information concerning the spatial structure and dynamics of excitons. 2D infrared spectroscopy has become a widely used tool for studying structural dynamics but is incapable of directly providing information concerning electronic excited states. 2D electronic-vibrational (2DEV) spectroscopy provides a link between these domains, directly connecting the electronic excitation with the vibrational structure of the system under study. In this work, we derive response functions for the 2DEV spectrum of a molecular dimer and propose a method by which 2DEV spectra could be used to directly measure the electronic site populations as a function of time following the initial electronic excitation. We present results from the response function simulations which show that our proposed approach is substantially valid. This method provides, to our knowledge, the first direct experimental method for measuring the electronic excited state dynamics in the spatial domain, on the molecular scale.

  11. Resonant core spectroscopies of the charge transfer interactions between C60 and the surfaces of Au(111), Ag(111), Cu(111) and Pt(111)

    Science.gov (United States)

    Gibson, Andrew J.; Temperton, Robert H.; Handrup, Karsten; O'Shea, James N.

    2017-03-01

    Charge transfer interactions between C60 and the metal surfaces of Ag(111), Cu(111), Au(111) and Pt(111) have been studied using synchrotron-based photoemission, resonant photoemission and X-ray absorption spectroscopies. By placing the X-ray absorption and valence band spectra on a common binding energy scale, the energetic overlap of the unoccupied molecular orbitals with the density of states of the underlying metal surface have been assessed in the context of possible charge transfer pathways. Resonant photoemission and resonant Auger data, measuring the valence region as a function of photon energy for C60 adsorbed on Au(111) reveals three constant high kinetic energy features associated with Auger-like core-hole decay involving an electron transferred from the surface to the LUMO of the molecule and electrons from the three highest occupied molecular orbitals, respectively and in the presence of ultra-fast charge transfer of the originally photoexcited molecule to the surface. Data for the C60/Ag(111) surface reveals an additional Auger-like feature arising from a core-hole decay process involving more than one electron transferred from the surface into the LUMO. An analysis of the relative abundance of these core-hole decay channels estimates that on average 2.4 ± 0.3 electrons are transferred from the Ag(111) surface into the LUMO. A core-hole clock analysis has also been applied to assess the charge transfer coupling in the other direction, from the molecule to the Au(111) and Ag(111) surfaces. Resonant photoemission and resonant Auger data for C60 molecules adsorbed on the Pt(111) and Cu(111) surfaces are shown to exhibit no super-Auger features, which is attributed to the strong modification of the unoccupied molecular orbitals arising from stronger chemical coupling of the molecule to the surface.

  12. Auger ACCESS—Remote Controlling and Monitoring the Pierre Auger Observatory

    Science.gov (United States)

    Jejkal, Thomas

    2013-10-01

    Ultra high energy cosmic rays are the most energetic particles in the universe. They are measured to have energies of up to 1020 eV and occur at a rate of about once per square kilometer per century. To increase the probability of detecting one of these events, a huge detector covering a large area is needed. The Pierre Auger Collaboration build up an observatory covering 3000 square kilometers of the Pampa Amarilla close to Malargüe for this purpose. Until now, the Auger Observatory has been controlled exclusively via the local network for security and performance reasons. As local operation is associated with high travel costs, the Auger ACCESS project, started in 2005, has constructed a secure, operable and sustainable solution for remote control and monitoring. The implemented solution includes Grid technologies for secured access and infrastructure virtualization for building up a fully featured testing environment for the Auger Observatory. Measurements showed only a negligible delay for communicating with the observatory in Argentina, which allows the establishment of remote control rooms in the near future for full remote operation and remarkable cost reduction.

  13. Measurement of cosmic ray air showers using MHz radio-detection techniques at the Pierre Auger Observatory

    Science.gov (United States)

    Kleifges, M.

    2013-08-01

    The measurement of radio signals from air showers is studied in detail with the Auger Engineering Radio Array (AERA) at the site of the Pierre Auger Observatory in Argentina. The first stage of AERA is in operation since March 2011 and consists of 24 autonomous radio detector stations. The design of the stations including the radio antennas, the electronics system and the communications system is presented. In the next 12 months AERA will grow to a size of 125 stations covering an area of about 16 km2. First results and improvements for this next stage of AERA will be discussed.

  14. Electron Paramagnetic Resonance Spectroscopy of Photosynthetic Systems and Inorganic Model Complexes.

    Science.gov (United States)

    Dexheimer, Susan Lynne

    1990-01-01

    This thesis discusses the application of parallel polarization electron paramagnetic resonance (EPR) spectroscopy, a technique sensitive to formally forbidden transitions in high spin states, to the study of the electronic structure of photosynthetic electron transfer centers and related inorganic model complexes. The theoretical basis for the origin of the parallel polarization transitions and the interpretation of the resulting spectra is presented, and experimental aspects of the detection of parallel polarization transitions are discussed. Parallel polarization EPR was used to study inorganic complexes of trivalent manganese that serve as models for the spectroscopic properties of biological electron transfer centers. X-band EPR spectra were detected from non-Kramers spin states of these complexes. EPR spectra of the S = 2 ground states of the mononuclear complexes Mn(III) tris -acetylacetonate and Mn(III) tris-picolinate and a low-lying excited state of the weakly antiferromagnetically coupled binuclear complex Mn_2(III,III) O(O_2CCH_3) _2 (HB(pz)_3) _2 (HB(pz)_3 = hydrotris(1-pyrazolyl)borate) are discussed. The spectra are interpreted using numerical simulations. Application of parallel polarization EPR to photosyntheic systems led to the detection of a new paramagnetic intermediate associated with photosynthetic water oxidation. The parallel polarization EPR signal is assigned to an S = 1 spin state of an exchange-coupled manganese center in the resting (S_1) state of the photosynthetic oxygen-evolving complex. The properties of the S _1 state parallel polarization EPR signal indicate that it corresponds to the reduced form of the species that gives rise to the previously established multiline conventional EPR signal in the light-induced S _2 state, and the behavior of the signal upon advancement to the S_2 state demonstrates the presence of two separate redox-active centers in the oxygen-evolving complex. The implications for the electronic structure of

  15. Electron energy loss spectroscopy on semiconductor heterostructures for optoelectronics and photonics applications.

    Science.gov (United States)

    Eljarrat, A; López-Conesa, L; Estradé, S; Peiró, F

    2016-05-01

    In this work, we present characterization methods for the analysis of nanometer-sized devices, based on silicon and III-V nitride semiconductor materials. These methods are devised in order to take advantage of the aberration corrected scanning transmission electron microscope, equipped with a monochromator. This set-up ensures the necessary high spatial and energy resolution for the characterization of the smallest structures. As with these experiments, we aim to obtain chemical and structural information, we use electron energy loss spectroscopy (EELS). The low-loss region of EELS is exploited, which features fundamental electronic properties of semiconductor materials and facilitates a high data throughput. We show how the detailed analysis of these spectra, using theoretical models and computational tools, can enhance the analytical power of EELS. In this sense, initially, results from the model-based fit of the plasmon peak are presented. Moreover, the application of multivariate analysis algorithms to low-loss EELS is explored. Finally, some physical limitations of the technique, such as spatial delocalization, are mentioned. © 2015 The Authors Journal of Microscopy © 2015 Royal Microscopical Society.

  16. Electron-beam-induced carbon contamination on silicon: characterization using Raman spectroscopy and atomic force microscopy.

    Science.gov (United States)

    Lau, Deborah; Hughes, Anthony E; Muster, Tim H; Davis, Timothy J; Glenn, A Matthew

    2010-02-01

    Electron-beam-induced carbon film deposition has long been recognized as a side effect of scanning electron microscopy. To characterize the nature of this type of contamination, silicon wafers were subjected to prolonged exposure to 15 kV electron beam energy with a probe current of 300 pA. Using Raman spectroscopy, the deposited coating was identified as an amorphous carbon film with an estimated crystallite size of 125 A. Using atomic force microscopy, the cross-sectional profile of the coating was found to be raised and textured, indicative of the beam raster pattern. A map of the Raman intensity across the coating showed increased intensity along the edges and at the corner of the film. The intensity profile was in excess of that which could be explained by thickness alone. The enhancement was found to correspond with a modeled local field enhancement induced by the coating boundary and showed that the deposited carbon coating generated a localized disturbance in the opto-electrical properties of the substrate, which is compared and contrasted with Raman edge enhancement that is produced by surface structure in silicon.

  17. Electronic and vibrational spectroscopy and vibrationally mediated photodissociation of V+(OCO).

    Science.gov (United States)

    Citir, Murat; Altinay, Gokhan; Metz, Ricardo B

    2006-04-20

    Electronic spectra of gas-phase V+(OCO) are measured in the near-infrared from 6050 to 7420 cm(-1) and in the visible from 15,500 to 16,560 cm(-1), using photofragment spectroscopy. The near-IR band is complex, with a 107 cm(-1) progression in the metal-ligand stretch. The visible band shows clearly resolved vibrational progressions in the metal-ligand stretch and rock, and in the OCO bend, as observed by Brucat and co-workers. A vibrational hot band gives the metal-ligand stretch frequency in the ground electronic state nu3'' = 210 cm(-1). The OCO antisymmetric stretch frequency in the ground electronic state (nu1'') is measured by using vibrationally mediated photodissociation. An IR laser vibrationally excites ions to nu1'' = 1. Vibrationally excited ions selectively dissociate following absorption of a second, visible photon at the nu1' = 1 CO2, due to interaction with the metal. Larger blue shifts observed for complexes with fewer ligands agree with trends seen for larger V+(OCO)n clusters.

  18. Electronic properties of graphene nano-flakes: Energy gap, permanent dipole, termination effect, and Raman spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Sandeep Kumar, E-mail: SandeepKumar.Singh@uantwerpen.be; Peeters, F. M., E-mail: Francois.Peeters@uantwerpen.be [Department of Physics, University of Antwerpen, Groenenborgerlaan 171, B-2020 Antwerpen (Belgium); Neek-Amal, M., E-mail: neekamal@srttu.edu [Department of Physics, University of Antwerpen, Groenenborgerlaan 171, B-2020 Antwerpen (Belgium); Department of Physics, Shahid Rajaee Teacher Training University, Lavizan, Tehran 16788 (Iran, Islamic Republic of)

    2014-02-21

    The electronic properties of graphene nano-flakes (GNFs) with different edge passivation are investigated by using density functional theory. Passivation with F and H atoms is considered: C{sub N{sub c}} X{sub N{sub x}} (X = F or H). We studied GNFs with 10 < N{sub c} < 56 and limit ourselves to the lowest energy configurations. We found that: (i) the energy difference Δ between the highest occupied molecular orbital and the lowest unoccupied molecular orbital decreases with N{sub c}, (ii) topological defects (pentagon and heptagon) break the symmetry of the GNFs and enhance the electric polarization, (iii) the mutual interaction of bilayer GNFs can be understood by dipole-dipole interaction which were found sensitive to the relative orientation of the GNFs, (iv) the permanent dipoles depend on the edge terminated atom, while the energy gap is independent of it, and (v) the presence of heptagon and pentagon defects in the GNFs results in the largest difference between the energy of the spin-up and spin-down electrons which is larger for the H-passivated GNFs as compared to F-passivated GNFs. Our study shows clearly the effect of geometry, size, termination, and bilayer on the electronic properties of small GNFs. This study reveals important features of graphene nano-flakes which can be detected using Raman spectroscopy.

  19. Electronic properties of graphene nano-flakes: Energy gap, permanent dipole, termination effect, and Raman spectroscopy

    Science.gov (United States)

    Singh, Sandeep Kumar; Neek-Amal, M.; Peeters, F. M.

    2014-02-01

    The electronic properties of graphene nano-flakes (GNFs) with different edge passivation are investigated by using density functional theory. Passivation with F and H atoms is considered: C_{N_c} X_{N_x} (X = F or H). We studied GNFs with 10 interaction of bilayer GNFs can be understood by dipole-dipole interaction which were found sensitive to the relative orientation of the GNFs, (iv) the permanent dipoles depend on the edge terminated atom, while the energy gap is independent of it, and (v) the presence of heptagon and pentagon defects in the GNFs results in the largest difference between the energy of the spin-up and spin-down electrons which is larger for the H-passivated GNFs as compared to F-passivated GNFs. Our study shows clearly the effect of geometry, size, termination, and bilayer on the electronic properties of small GNFs. This study reveals important features of graphene nano-flakes which can be detected using Raman spectroscopy.

  20. The Cherenkov Surface Detector of the Pierre Auger Observatory

    Energy Technology Data Exchange (ETDEWEB)

    Billoir, Pierre, E-mail: billoir@lpnhe.in2p3.fr [LPNHE, CNRS/IN2P3 and Univ. P. and M. Curie and Univ. D. Diderot, 4 place Jussieu 75272 Paris Cedex 05 (France); Observatorio Pierre Auger, av. San Martín Norte, 304 5613, Malargüe (Argentina)

    2014-12-01

    The Pierre Auger Observatory detects the atmospheric showers induced by cosmic rays of ultra-high energy (UHE). It is the first one to use the hybrid technique. A set of telescopes observes the fluorescence of the nitrogen molecules on clear moonless nights, giving access to the longitudinal profile of the shower. These telescopes surround a giant array of 1600 water Cherenkov tanks (covering more than 3000 km{sup 2}), which works continuously and samples the particles reaching the ground (mainly muons, photons and electrons/positrons); the light produced within the water is recorded into FADC (Fast Analog to Digital Convertes) traces. A subsample of hybrid events provides a cross calibration of the two components. We describe the structure of the Cherenkov detectors, their sensitivity to different particles and the information they can give on the direction of origin, the energy and the nature of the primary UHE object; we discuss also their discrimination power for rare events (UHE photons or neutrinos). To cope with the variability of weather conditions and the limitations of the communication system, the procedures for trigger and real time calibration have been shared between local processors and a central acquisition system. The overall system has been working almost continuously for 10 years, while being progressively completed and increased by the creation of a dense “infill” subarray. - Highlights: • The water Cherenkov technique is used in the Surface Detector of the Pierre Auger Observatory. • Cross-calibrated with the Fluorescence Detector, it provides a measurement of the primary energy. • The spectrum of the UHE cosmic rays exhibits clearly an “ankle” and a cutoff. • The muon observed muon content of the atmospheric showers is larger than expected from the models. • Stringent limits on the flux of UHE neutrinos and photons are obtained.

  1. K-shell auger decay of atomic oxygen

    Energy Technology Data Exchange (ETDEWEB)

    Stolte, W.C.; Lu, Y.; Samson, J.A.R. [Univ. of Nebraska, Lincoln, NE (United States)] [and others

    1997-04-01

    The aim of the present research is to understand the interaction between the ejected photoelectron and Auger electron produced by the Auger decay of a 1s hole in atomic oxygen, and to understand the influence this interaction has on the shape of the ionization cross sections. To accomplish this the authors have measured the relative ion yields (ion/photon) in the vicinity of the oxygen K-shell (525 - 533 eV) for O{sup +} and O{sup 2+}. The measurements were performed at the ALS on beamline, 6.3.2. The atomic oxygen was produced by passing molecular oxygen through a microwave-driven discharge. A Rydberg analysis of the two series leading to the [1s]2s{sup 2}2p{sup 4}({sup 4}P) and [1s]2s{sup 2}2p{sup 4}({sup 2}P) limits were obtained. This analysis shows some differences to the recently published results by Menzel et al. The energy position of the main 1s{sup 1}2s{sup 2}2p{sup 5}({sup 3}P) resonance differs by approximately 1 eV from the authors value, all members of the ({sup 2}P)np series differ by 0.3 eV, but the members of the ({sup 4}P)np series agree. The molecular resonance at 530.5 eV and those between 539 eV and 543 eV, measured with the microwave discharge off show identical results in both experiments.

  2. Electronic structure of four-coordinate C3v nickel(II) scorpionate complexes: investigation by high-frequency and -field electron paramagnetic resonance and electronic absorption spectroscopies.

    Science.gov (United States)

    Desrochers, Patrick J; Telser, Joshua; Zvyagin, S A; Ozarowski, Andrew; Krzystek, J; Vicic, David A

    2006-10-30

    A series of complexes of formula TpNiX, where Tp*- = hydrotris(3,5-dimethylpyrazole)borate and X = Cl, Br, I, has been characterized by electronic absorption spectroscopy in the visible and near-infrared (NIR) region and by high-frequency and -field electron paramagnetic resonance (HFEPR) spectroscopy. The crystal structure of TpNiCl has been previously reported; that for TpNiBr is given here: space group = Pmc2(1), a = 13.209(2) A, b = 8.082(2) A, c = 17.639(4) A, alpha = beta = gamma = 90 degrees , Z = 4. TpNiX contains a four-coordinate nickel(II) ion (3d8) with approximate C3v point group symmetry about the metal and a resulting S = 1 high-spin ground state. As a consequence of sizable zero-field splitting (zfs), TpNiX complexes are "EPR silent" with use of conventional EPR; however, HFEPR allows observation of multiple transitions. Analysis of the resonance field versus the frequency dependence of these transitions allows extraction of the full set of spin Hamiltonian parameters. The axial zfs parameter for TpNiX displays pronounced halogen contributions down the series: D = +3.93(2), -11.43(3), -22.81(1) cm(-1), for X = Cl, Br, I, respectively. The magnitude and change in sign of D observed for TpNiX reflects the increasing bromine and iodine spin-orbit contributions facilitated by strong covalent interactions with nickel(II). These spin Hamiltonian parameters are combined with estimates of 3d energy levels based on the visible-NIR spectra to yield ligand-field parameters for these complexes following the angular overlap model (AOM). This description of electronic structure and bonding in a pseudotetrahedral nickel(II) complex can enhance the understanding of similar sites in metalloproteins, both native nickel enzymes and nickel-substituted zinc enzymes.

  3. Investigation of radiosterilization of Benzydamine Hydrochloride by electron spin resonance spectroscopy

    Science.gov (United States)

    Çolak, Şeyda

    2016-10-01

    The use of ionizing radiation for sterilization of pharmaceuticals is an attractive and growing technology. In the present work, the spectroscopic and kinetic features of the radicals induced in gamma irradiated solid Benzydamine Hydrochloride (BH) sample is investigated in the dose range of 3-34 kGy at different temperatures using Electron Spin Resonance (ESR) spectroscopy. Gamma irradiated BH indicated eight resonance peaks centered at g=2.0029 originating from two different radical species. Decay activation energy of the radical mostly responsible from central intense resonance line was calculated to be 25.6±1.5 kJ/mol by using the signal intensity decay data derived from annealing studies performed at high temperatures. A linear function of the applied dose was found to describe best the experimental dose-response data. However, the discrimination of irradiated BH from unirradiated one was possible even 3 months after storage at normal conditions. Basing on these findings it was concluded that BH and BH containing drugs could be safely sterilized by gamma radiation and that ESR spectroscopy could be successfully used as a potential technique for monitoring their radiosterilizations.

  4. Characterization of the nanomorphology of polymer-silica colloidal nanocomposites using electron spectroscopy imaging.

    Science.gov (United States)

    Amalvy, J I; Percy, M J; Armes, S P; Leite, C A P; Galembeck, F

    2005-02-15

    The internal nanomorphologies of two types of vinyl polymer-silica colloidal nanocomposites were assessed using electron spectroscopy imaging (ESI). This technique enables the spatial location and concentration of the ultrafine silica sol within the nanocomposite particles to be determined. The ESI data confirmed that the ultrafine silica sol was distributed uniformly throughout the poly(4-vinylpyridine)/silica nanocomposite particles, which is consistent with the "currant bun" morphology previously used to describe this system. In contrast, the polystyrene/silica particles had a pronounced "core-shell" morphology, with the silica sol forming a well-defined monolayer surrounding the nanocomposite cores. Thus these ESI results provide direct verification of the two types of nanocomposite morphologies that were previously only inferred on the basis of X-ray photoelectron spectroscopy and aqueous electrophoresis studies. Moreover, ESI also allows the unambiguous identification of a minor population of polystyrene/silica nanocomposite particles that are not encapsulated by silica shells. The existence of this second morphology was hitherto unsuspected, but it is understandable given the conditions employed to synthesize these nanocomposites. It appears that ESI is a powerful technique for the characterization of colloidal nanocomposite particles.

  5. Addressing the electronic properties of III-V nanowires by photoluminescence excitation spectroscopy

    Science.gov (United States)

    De Luca, M.

    2017-02-01

    Semiconductor nanowires (NWs) have been attracting an increasing interest in the scientific community. This is due to their peculiar filamentary shape and nanoscale diameter, which renders them versatile and cost-effective components of novel technological devices and also makes them an ideal platform for the investigation of a variety of fascinating physical effects. Absorption spectroscopy is a powerful and non-destructive technique able to provide information on the physical properties of the NWs. However, standard absorption spectroscopy is hard to perform in NWs, because of their small volume and the presence of opaque substrates. Here, we demonstrate that absorption can be successfully replaced by photoluminescence excitation (PLE). First, the use of polarization-resolved PLE to address the complex and highly-debated electronic band structure of wurtzite GaAs and InP NWs is shown. Then, PLE is used as a statistically-relevant method to localize the presence of separate wurtzite and zincblende NWs in the same InP sample. Finally, a variety of resonant exotic effects in the density of states of In x Ga1-x As/GaAs core/shell NWs are highlighted by high-resolution PLE. , which features invited work from the best early-career researchers working within the scope of J. Phys. D. This project is part of the Journal of Physics’ series 50th anniversary celebrations in 2017. Marta De Luca was selected by the Editorial Board of J. Phys. D as a Leader.

  6. [Combination of near infrared spectroscopy and electronic nose for alcohol quantification during the red wine fermentation].

    Science.gov (United States)

    Zhang, Shu-Ming; Yang, Yang; Ni, Yuan-Ying

    2012-11-01

    The red wine fermentation needs fast and nondestructive techniques, which can help to control the fermentation process and assure the quality of wine. In the present study, near infrared spectroscopy (NIR) and electronic nose (EN) were used to predict the alcohol content during the red wine alcoholic fermentation. Calibration models were developed between instru- mental data and chemical analysis using principal component regression (PCR) and partial least squares regression (PLSR) with cross validation. Good correlations (R > 0.99) were acquired for both the models developed by the NIR and EN data. However, RMSEC and RMSEP were a little larger. Combining NIR and EN can optimize the model and improve the prediction accuracy. The PLSR model based on combined data shows the best correlation (R = 0.999 2), with RMSEC and RMSEP being 0. 206 and 0.205% (v/v), respectively. Both NIR spectroscopy and EN can predict the alcohol concentration during the alcoholic fermentation of red wine, and the combination of two instruments can improve the analysis precision. Although the measurements were carried out in off-line mode, this study demonstrates that NIR and EN can be used as on line, fast, nondestructive and in time techniques to provide in-time information about the fermentation process and to assure the quality of final products.

  7. Application of a voltammetric electronic tongue and near infrared spectroscopy for a rapid umami taste assessment.

    Science.gov (United States)

    Bagnasco, Lucia; Cosulich, M Elisabetta; Speranza, Giovanna; Medini, Luca; Oliveri, Paolo; Lanteri, Silvia

    2014-08-15

    The relationships between sensory attribute and analytical measurements, performed by electronic tongue (ET) and near-infrared spectroscopy (NIRS), were investigated in order to develop a rapid method for the assessment of umami taste. Commercially available umami products and some aminoacids were submitted to sensory analysis. Results were analysed in comparison with the outcomes of analytical measurements. Multivariate exploratory analysis was performed by principal component analysis (PCA). Calibration models for prediction of the umami taste on the basis of ET and NIR signals were obtained using partial least squares (PLS) regression. Different approaches for merging data from the two different analytical instruments were considered. Both of the techniques demonstrated to provide information related with umami taste. In particular, ET signals showed the higher correlation with umami attribute. Data fusion was found to be slightly beneficial - not so significantly as to justify the coupled use of the two analytical techniques. Copyright © 2014 Elsevier Ltd. All rights reserved.

  8. Vibrational Inelastic Electron Tunneling Spectroscopy of Single Acetylene Molecules Adsorbed on Copper (100) Surface

    OpenAIRE

    Jiang, Chi-Lun

    2015-01-01

    With a 600mk homebuilt UHV STM system, we studied molecular vibration at the solid surface with inelastic electron tunneling spectroscopy (IETS) of Acetylene single molecules adsorbed on Cu(100) surface. The identification of vibrational IETS features with normalized conductance change (Δσ/σ) as low as 0.24% in dI2/d2V spectra was demonstrated. Five vibrational modes with energy level at 117.70meV (Δσ/σ =0.42%), 84.07meV (Δσ/σ =0.24%), 58.46meV (Δσ/σ =1.18%), 34.80meV (Δσ/σ =0.65% ) and 22.1...

  9. Probing the local environment of a single OPE3 molecule using inelastic tunneling electron spectroscopy

    Directory of Open Access Journals (Sweden)

    Riccardo Frisenda

    2015-12-01

    Full Text Available We study single-molecule oligo(phenylene ethynylenedithiol junctions by means of inelastic electron tunneling spectroscopy (IETS. The molecule is contacted with gold nano-electrodes formed with the mechanically controllable break junction technique. We record the IETS spectrum of the molecule from direct current measurements, both as a function of time and electrode separation. We find that for fixed electrode separation the molecule switches between various configurations, which are characterized by different IETS spectra. Similar variations in the IETS signal are observed during atomic rearrangements upon stretching of the molecular junction. Using quantum chemistry calculations, we identity some of the vibrational modes which constitute a chemical fingerprint of the molecule. In addition, changes can be attributed to rearrangements of the local molecular environment, in particular at the molecule–electrode interface. This study shows the importance of taking into account the interaction with the electrodes when describing inelastic contributions to transport through single-molecule junctions.

  10. Probing the local environment of a single OPE3 molecule using inelastic tunneling electron spectroscopy.

    Science.gov (United States)

    Frisenda, Riccardo; Perrin, Mickael L; van der Zant, Herre S J

    2015-01-01

    We study single-molecule oligo(phenylene ethynylene)dithiol junctions by means of inelastic electron tunneling spectroscopy (IETS). The molecule is contacted with gold nano-electrodes formed with the mechanically controllable break junction technique. We record the IETS spectrum of the molecule from direct current measurements, both as a function of time and electrode separation. We find that for fixed electrode separation the molecule switches between various configurations, which are characterized by different IETS spectra. Similar variations in the IETS signal are observed during atomic rearrangements upon stretching of the molecular junction. Using quantum chemistry calculations, we identity some of the vibrational modes which constitute a chemical fingerprint of the molecule. In addition, changes can be attributed to rearrangements of the local molecular environment, in particular at the molecule-electrode interface. This study shows the importance of taking into account the interaction with the electrodes when describing inelastic contributions to transport through single-molecule junctions.

  11. Electronic and vibrational spectroscopy of intermediates in methane-to-methanol conversion by CoO+

    Science.gov (United States)

    Altinay, Gokhan; Kocak, Abdulkadir; Silva Daluz, Jennifer; Metz, Ricardo B.

    2011-08-01

    At room temperature, cobalt oxide cations directly convert methane to methanol with high selectivity but very low efficiency. Two potential intermediates of this reaction, the [HO-Co-CH3]+ insertion intermediate and [H2O-Co=CH2]+ aquo-carbene complex are produced in a laser ablation source and characterized by electronic and vibrational spectroscopy. Reaction of laser-ablated cobalt cations with different organic precursors seeded in a carrier gas produces the intermediates, which subsequently expand into vacuum and cool. Ions are extracted into a time-of-flight mass spectrometer and spectra are measured via photofragment spectroscopy. Photodissociation of [HO-Co-CH3]+ in the visible and via infrared multiple photon dissociation (IRMPD) makes only Co+ + CH3OH, while photodissociation of [H2O-Co=CH2]+ produces CoCH2+ + H2O. The electronic spectrum of [HO-Co-CH3]+ shows progressions in the excited state Co-C stretch (335 cm-1) and O-Co-C bend (90 cm-1); the IRMPD spectrum gives νOH = 3630 cm-1. The [HO-Co-CH3]+(Ar) complex has been synthesized and its vibrational spectrum measured in the O-H stretching region. The resulting spectrum is sharper than that obtained via IRMPD and gives νOH = 3642 cm-1. Also, an improved potential energy surface for the reaction of CoO+ with methane has been developed using single point energies calculated by the CBS-QB3 method for reactants, intermediates, transition states and products.

  12. Studies of the structure of insulin fibrils by Fourier transform infrared (FTIR) spectroscopy and electron microscopy.

    Science.gov (United States)

    Nielsen, L; Frokjaer, S; Carpenter, J F; Brange, J

    2001-01-01

    Fibril formation (aggregation) of insulin was investigated in acid media by visual inspection, transmission electron microscopy (TEM), and Fourier transform infrared (FTIR) spectroscopy. Insulin fibrillated faster in hydrochloric acid than in acetic acid at elevated temperatures, whereas the fibrillation tendencies were reversed at ambient temperatures. Electron micrographs showed that bovine insulin fibrils consisted of long fibers with a diameter of 5 to 10 nm and lengths of several microns. The fibrils appeared either as helical filaments (in hydrochloric acid) or arranged laterally in bundles (in acetic acid, NaCl). Freeze-thawing cycles broke the fibrils into shorter segments. FTIR spectroscopy showed that the native secondary structure of insulin was identical in hydrochloric acid and acetic acid, whereas the secondary structure of fibrils formed in hydrochloric acid was different from that formed in acetic acid. Fibrils of bovine insulin prepared by heating or agitating an acid solution of insulin showed an increased content of beta-sheet (mostly intermolecular) and a decrease in the intensity of the alpha-helix band. In hydrochloric acid, the frequencies of the beta-sheet bands depended on whether the fibrillation was induced by heating or agitation. This difference was not seen in acetic acid. Freeze-thawing cycles of the fibrils in hydrochloric acid caused an increase in the intensity of the band at 1635 cm(-1) concomitant with reduction of the band at 1622 cm(-1). The results showed that the structure of insulin fibrils is highly dependent on the composition of the acid media and on the treatment. Copyright 2001 Wiley-Liss Inc. and the American Pharmaceutical Association J Pharm Sci 90: 29-37, 2001

  13. Ultra-Broadband Two-Dimensional Electronic Spectroscopy and Pump-Probe Microscopy of Molecular Systems

    Science.gov (United States)

    Spokoyny, Boris M.

    Ultrafast spectroscopy offers an unprecedented view on the dynamic nature of chemical reactions. From charge transfer in semiconductors to folding and isomerization of proteins, these all important processes can now be monitored and in some instances even controlled on real, physical timescales. One of the biggest challenges of ultrafast science is the incredible energetic complexity of most systems. It is not uncommon to encounter macromolecules or materials with absorption spectra spanning significant portions of the visible spectrum. Monitoring a multitude of electronic and vibrational transitions, all dynamically interacting with each other on femtosecond timescales poses a truly daunting experimental task. The first part of this thesis deals with the development of a novel Two-Dimensional Electronic Spectroscopy (2DES) and its associated, advanced detection methodologies. Owing to its ultra-broadband implementation, this technique enables us to monitor femtosecond chemical dynamics that span the energetic landscape of the entire visible spectrum. In order to demonstrate the utility of our method, we apply it to two laser dye molecules, IR-144 and Cresyl Violet. Variation of photophysical properties on a microscopic scale in either man-made or naturally occurring systems can have profound implications on how we understand their macroscopic properties. Recently, inorganic hybrid perovskites have been tapped as the next generation solar energy harvesting materials. Their remarkable properties include low exciton binding energy, low exciton recombination rates and long carrier diffusion lengths. Nevertheless, considerable variability in device properties made with nearly identical preparation methods has puzzled the community. In the second part of this thesis we use non-linear pump probe microscopy to study the heterogeneous nature of femtosecond carrier dynamics in thin film perovskites. We show that the local morphology of the perovskite thin films has a

  14. Characterization of Inx Ga1-x As-GaAs heterostructures via electron beam techniques

    Science.gov (United States)

    Gomez-Barojas, Estela; Silva-Gonzalez, Rutilo; Serrano-Rojas, Rosa Maria; Vidal-Borbolla, Miguel Angel

    2005-03-01

    In the case of strained superlattices abrupt heterointerfaces are required because compositional fluctuations at heterointerfaces results in uncertainty in both composition and lattice constant. The aim of this work is to study exsitu the surface morphology, the periodicity and elemental composition of a set of 3 InGaAs-GaAs heterostructures grown on GaAs (100) substrates by a molecular beam epitaxy system. The heterostructures are formed by 10 periods of InGaAs-GaAs epitaxially grown on GaAs substrates with nominal thickness of 500 and 1000 å, respectively. The techniques used for this purpose are the scanning electron microscopy (SEM) and Auger electron spectroscopy (AES). The In content in the heterostructures is determined from corresponding Auger depth profiles. This work has been supported by VIEP-BUAP, Project No. II53G02.

  15. Enrichment of boron at grain boundaries of platinum-based alloys determined by electron energy loss spectroscopy in a transmission electron microscope

    Energy Technology Data Exchange (ETDEWEB)

    Preussner, Johannes [Fraunhofer Institute for Mechanics of Materials (IWM), Freiburg (Germany); Karlsruhe Institue of Technology, Karlsruhe (DE). Inst. for Reliability of Components and Systems (izbs); Fleischmann, Ernst; Voelkl, Rainer; Glatzel, Uwe [Bayreuth Univ. (Germany). Metals and Alloys

    2010-05-15

    Polycrystalline platinum-based alloys show very good creep properties at high temperatures. Small amounts of boron (less than 1 at.%) considerably increase the creep strength. Transmission electron microscopy measurements were conducted to localize the element boron in the samples. With image electron energy loss spectroscopy spectra were extracted revealing an enrichment of B at grain boundaries. The boron distribution was plotted with the three window method. (orig.)

  16. Biophysical Characterisation of Globins and Multi-Heme Cytochromes Using Electron Paramagnetic Resonance and Optical Spectroscopy

    Science.gov (United States)

    Desmet, Filip

    Heme proteins of different families were investigated in this work, using a combination of pulsed and continuous-wave electron paramagnetic resonance (EPR) spectroscopy, optical absorption spectroscopy, resonance Raman spectroscopy and laser flash photolysis. The first class of proteins that were investigated, were the globins. The globin-domain of the globin-coupled sensor of the bacterium Geobacter sulfurreducens was studied in detail using different pulsed EPR techniques (HYSCORE and Mims ENDOR). The results of this pulsed EPR study are compared with the results of the optical investigation and the crystal structure of the protein. The second globin, which was studied, is the Protoglobin of Methanosarcina acetivorans, various mutants of this protein were studied using laser flash photolysis and Raman spectroscopy to unravel the link between this protein's unusual structure and its ligand-binding kinetics. In addition to this, the CN -bound form of this protein was investigated using EPR and the influence of the strong deformation of the heme on the unusual low gz values is discussed. Finally, the neuroglobins of three species of fishes, Danio rerio, Dissostichus mawsoni and Chaenocephalus aceratus are studied. The influence of the presence or absence of two cysteine residues in the C-D and D-region of the protein on the EPR spectrum, and the possible formation of a disulfide bond is studied. The second group of proteins that were studied in this thesis belong to the family of the cytochromes. First the Mouse tumor suppressor cytochrome b561 was studied, the results of a Raman and EPR investigation are compared to the Human orthologue of the protein. Secondly, the tonoplast cytochrome b561 of Arabidopsis was investigated in its natural form and in two double-mutant forms, in which the heme at the extravesicular side was removed. The results of this investigation are then compared with two models in literature that predict the localisation of the hemes in this

  17. Limitations of superfluid helium droplets as host system revealed by electronic spectroscopy of embedded molecules

    Energy Technology Data Exchange (ETDEWEB)

    Premke, Tobias

    2016-02-19

    Superfluid helium nanodroplets serve a unique cryogenic host system ideal to prepare cold molecules and clusters. Structures as well as dynamic processes can be examined by means of high resolution spectroscopy. Dopant spectra are accompanied by helium-induced spectroscopic features which reveal information on the dopant to helium interaction. For this reason the experimental research focuses on the investigation of such helium-induced effects in order to provide new information on the microsolvation inside the droplets. Since the quantitative understanding of helium-induced spectral features is essential to interpret molecular spectra recorded in helium droplets, this study contributes further experimental details on microsolvation in superfluid helium droplets. For this purpose two contrary systems were examined by means of high resolution electronic spectroscopy. The first one, phthalocyanine (Pc), is a planar organic molecule offering a huge and planar surface to the helium atoms and thus, the non-superfluid helium solvation layer can form different structures. The second system is iodine and in contrast to Pc it is of simple molecular shape. That means that in this case different complex structures of the non-superfluid helium solvation layer and the dopant can be expected to be avoided. Thus, both molecules should show clear differences in their microsolvation behavior. In this work a detailed examination of different spectroscopic properties of phthalocyanine is given by means of fluorescence excitation and dispersed emission spectroscopy. It raises legitimate doubts about the assignment of experimentally observed signals to features predicted by the model of the microsolvation. Even though there are no experimental observations which disprove the empirical model for the solvation in helium droplets, an unambiguous assignment of the helium-induced spectroscopic structures is often not possible. In the second part of this work, the investigation of the

  18. Spin noise spectroscopy in GaAs (110) quantum wells: access to intrinsic spin lifetimes and equilibrium electron dynamics.

    Science.gov (United States)

    Müller, Georg M; Römer, Michael; Schuh, Dieter; Wegscheider, Werner; Hübner, Jens; Oestreich, Michael

    2008-11-14

    In this Letter, the first spin noise spectroscopy measurements in semiconductor systems of reduced effective dimensionality are reported. The nondemolition measurement technique gives access to the otherwise concealed intrinsic, low temperature electron spin relaxation time of n-doped GaAs (110) quantum wells and to the corresponding low temperature anisotropic spin relaxation. The Brownian motion of the electrons within the spin noise probe laser spot becomes manifest in a modification of the spin noise line width. Thereby, the spatially resolved observation of the stochastic spin polarization uniquely allows to study electron dynamics at equilibrium conditions with a vanishing total momentum of the electron system.

  19. Numerical evaluation of Auger recombination coefficients in relaxed and strained germanium

    Energy Technology Data Exchange (ETDEWEB)

    Dominici, Stefano [Dipartimento di Elettronica e Telecomunicazioni, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino (Italy); Department of Electrical and Computer Engineering, Boston University, 8 Saint Mary' s Street, Boston, Massachusetts 02215 (United States); Wen, Hanqing; Bellotti, Enrico [Department of Electrical and Computer Engineering, Boston University, 8 Saint Mary' s Street, Boston, Massachusetts 02215 (United States); Bertazzi, Francesco; Goano, Michele [Dipartimento di Elettronica e Telecomunicazioni, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino (Italy); IEIIT-CNR, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino (Italy)

    2016-05-23

    The potential applications of germanium and its alloys in infrared silicon-based photonics have led to a renewed interest in their optical properties. In this letter, we report on the numerical determination of Auger coefficients at T = 300 K for relaxed and biaxially strained germanium. We use a Green's function based model that takes into account all relevant direct and phonon-assisted processes and perform calculations up to a strain level corresponding to the transition from indirect to direct energy gap. We have considered excess carrier concentrations ranging from 10{sup 16} cm{sup −3} to 5 × 10{sup 19} cm{sup −3}. For use in device level simulations, we also provide fitting formulas for the calculated electron and hole Auger coefficients as functions of carrier density.

  20. Numerical evaluation of Auger recombination coefficients in relaxed and strained germanium

    Science.gov (United States)

    Dominici, Stefano; Wen, Hanqing; Bertazzi, Francesco; Goano, Michele; Bellotti, Enrico

    2016-05-01

    The potential applications of germanium and its alloys in infrared silicon-based photonics have led to a renewed interest in their optical properties. In this letter, we report on the numerical determination of Auger coefficients at T = 300 K for relaxed and biaxially strained germanium. We use a Green's function based model that takes into account all relevant direct and phonon-assisted processes and perform calculations up to a strain level corresponding to the transition from indirect to direct energy gap. We have considered excess carrier concentrations ranging from 1016 cm-3 to 5 × 1019 cm-3. For use in device level simulations, we also provide fitting formulas for the calculated electron and hole Auger coefficients as functions of carrier density.

  1. Electronic properties of novel topological quantum materials studied by angle-resolved photoemission spectroscopy (ARPES)

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Yun [Iowa State Univ., Ames, IA (United States)

    2016-12-17

    The discovery of quantum Hall e ect has motivated the use of topology instead of broken symmetry to classify the states of matter. Quantum spin Hall e ect has been proposed to have a separation of spin currents as an analogue of the charge currents separation in quantum Hall e ect, leading us to the era of topological insulators. Three-dimensional analogue of the Dirac state in graphene has brought us the three-dimensional Dirac states. Materials with three-dimensional Dirac states could potentially be the parent compounds for Weyl semimetals and topological insulators when time-reversal or space inversion symmetry is broken. In addition to the single Dirac point linking the two dispersion cones in the Dirac/Weyl semimetals, Dirac points can form a line in the momentum space, resulting in a topological node line semimetal. These fascinating novel topological quantum materials could provide us platforms for studying the relativistic physics in condensed matter systems and potentially lead to design of new electronic devices that run faster and consume less power than traditional, silicon based transistors. In this thesis, we present the electronic properties of novel topological quantum materials studied by angle-resolved photoemission spectroscopy (ARPES).

  2. Mapping bright and dark modes in gold nanoparticle chains using electron energy loss spectroscopy.

    Science.gov (United States)

    Barrow, Steven J; Rossouw, David; Funston, Alison M; Botton, Gianluigi A; Mulvaney, Paul

    2014-07-09

    We present a scanning transmission electron microscopy-electron energy loss spectroscopy (STEM-EELS) investigation of gold nanosphere chains with lengths varying from 1 to 5 particles. We show localized EELS signals from the chains and identify energy-loss peaks arising due to l = 1, 2, 3, 4, and 5 plasmon modes through the use of EELS mapping. We also show the evolution of the energy of these modes as the length of a given chain increases, and we find that a chain containing N particles can accommodate at least N experimentally observable modes, in addition to the transverse mode. As the chain length is increased by the addition of one more gold particle to the chain, the new N + 1 mode becomes the highest energy mode, while the existing modes lower their energy and eventually asymptote as they delocalize along the chain. We also show that modes become increasingly difficult to detect with the EELS technique as l approaches N. The data are compared to numerical simulations.

  3. Electron spin resonance spectroscopy of high purity crystals at millikelvin temperatures

    Science.gov (United States)

    Farr, Warrick G.; Creedon, Daniel L.; Goryachev, Maxim; Benmessai, Karim; Tobar, Michael E.

    2013-12-01

    Progress in the emerging field of engineered quantum systems requires the development of devices that can act as quantum memories. The realisation of such devices by doping solid state cavities with paramagnetic ions imposes a trade-off between ion concentration and cavity coherence time. Here, we investigate an alternative approach involving interactions between photons and naturally occurring impurity ions in ultra-pure crystalline microwave cavities exhibiting exceptionally high quality factors. We implement a hybrid Whispering Gallery/Electron Spin Resonance method to perform rigorous spectroscopy of an undoped single-crystal sapphire resonator over the frequency range 8{19 GHz, and at external applied DC magnetic fields up to 0.9 T. Measurements of a high purity sapphire cooled close to 100 mK reveal the presence of Fe3+, Cr3+, and V2+ impurities. A host of electron transitions are measured and identified, including the two-photon classically forbidden quadrupole transition (Δms = 2) for Fe3+, as well as hyperfine transitions of V2+.

  4. Multidimensional electron-nuclear wavepacket dynamics via Time-, Energy- and Angle-resolved Photoelectron Spectroscopy

    Science.gov (United States)

    Veyrinas, K.; Makhija, V.; Boguslavskiy, A. E.; Forbes, R.; Wilkinson, I.; Moffatt, D.; Lausten, R.; Stolow, A.

    2017-04-01

    Generating and probing a coherent superposition of coupled vibrational-electronic (vibronic) states - a multidimensional wavepacket - remains a challenging problem in molecular dynamics. Here, we present recent results using time-resolved photoelectron velocity map imaging (VMI) of complex vibronic wavepacket dynamics in the NO molecule following femtosecond single photon excitation in the vacuum ultraviolet (VUV) range (λpump = 160 nm, 80 fs). The induced ultrafast dynamics, involving highly excited valence and Rydberg states, is probed by single photon ionization (λprobe = 400 nm, 40 fs). Varying the pump-probe time delay, the emitted photoelectrons are detected in a VMI spectrometer for time-, energy- and angle-resolved photoelectron spectroscopy. We observe that the different final vibrational states of the NO+ (X 1Σ+) cation, onto which this evolving vibronic wavepacket is projected, reveal different time dependences for the kinetic energy distribution and the laboratory frame photoelectron angular distribution (LFPAD). In particular, we observe unusually strong oscillations in the β4 asymmetry parameter, indicating sensitivity to the higher angular momentum components of the electronic aspect of this complex vibronic wavepacket.

  5. Adsorption on metal oxides Studies with the metastable impact electron spectroscopy

    CERN Document Server

    Krischok, S; Kempter, V

    2002-01-01

    An overview is given on the application of metastable impact electron spectroscopy, in combination with UPS, to the study of clean magnesia and titania surfaces and their interaction with metal atoms and small molecules. The mechanisms for metal adsorption on reducible (titania) and non-reducible (magnesia) substrates are different: while on titania the metal atom often bonds by electron transfer to Ti3d states, it is hybridization of the adsorbate and anion wavefunctions which accounts for the bonding on MgO. In the case of H sub 2 O, molecular adsorption takes place both on MgO and TiO sub 2; on the other hand, water-alkali coadsorption leads to hydroxide formation. In the case of CO sub 2 , chemisorption takes place in form of carbonate (CO sub 3) species. These originate from the CO sub 2 interaction with O sup 2 sup - surface anions. While for CaO chemisorption takes place at regular oxygen sites, for MgO this occurs at low-coordinated oxygen ions only; for TiO sub 2 chemisorption requires alkali coadsor...

  6. Probing Homogeneous Line Broadening in CdSe Nanocrystals Using Multidimensional Electronic Spectroscopy.

    Science.gov (United States)

    Gellen, Tobias A; Lem, Jet; Turner, Daniel B

    2017-05-10

    The finite spectral line width of an ensemble of CdSe nanocrystals arises from size and shape inhomogeneity and the single-nanocrystal spectrum itself. This line width directly limits the performance of nanocrystal-based devices, yet most optical measurements cannot resolve the underlying contributions. We use two-dimensional electronic spectroscopy (2D ES) to measure the line width of the band-edge exciton of CdSe nanocrystals as a function of radii and surface chemistry. We find that the homogeneous width decreases for increasing nanocrystal radius and that surface chemistry plays a critical role in controlling this line width. To explore the hypothesis that unpassivated trap states serve to broaden the homogeneous line width and to explain its size-dependence, we use 3D ES to identify the spectral signatures of exciton-phonon coupling to optical and acoustic phonons. We find enhanced coupling to optical phonon modes for nanocrystals that lack electron-passivating ligands, suggesting that localized surface charges enhance exciton-phonon coupling via the Fröhlich interaction. Lastly, the data reveal that spectral diffusion contributes negligibly to the homogeneous line width on subnanosecond time scales.

  7. Time-resolved X-ray Absorption Spectroscopy for Electron Transport Study in Warm Dense Gold

    Science.gov (United States)

    Lee, Jong-Won; Bae, Leejin; Engelhorn, Kyle; Heimann, Philip; Ping, Yuan; Barbrel, Ben; Fernandez, Amalia; Beckwith, Martha Anne; Cho, Byoung-Ick; GIST Team; IBS Team; LBNL Collaboration; SLAC Collaboration; LLNL Collaboration

    2015-11-01

    The warm dense Matter represents states of which the temperature is comparable to Fermi energy and ions are strongly coupled. One of the experimental techniques to create such state in the laboratory condition is the isochoric heating of thin metal foil with femtosecond laser pulses. This concept largely relies on the ballistic transport of electrons near the Fermi-level, which were mainly studied for the metals in ambient conditions. However, they were barely investigated in warm dense conditions. We present a time-resolved x-ray absorption spectroscopy measured for the Au/Cu dual layered sample. The front Au layer was isochorically heated with a femtosecond laser pulse, and the x-ray absorption changes around L-edge of Cu, which was attached on the backside of Au, was measured with a picosecond resolution. Time delays between the heating of the `front surface' of Au layer and the alternation of x-ray spectrum of Cu attached on the `rear surface' of Au indicate the energetic electron transport mechanism through Au in the warm dense conditions. IBS (IBS-R012-D1) and the NRF (No. 2013R1A1A1007084) of Korea.

  8. High-resolution electron spectroscopy and structures of lithium-nucleobase (adenine, uracil, and thymine) complexes.

    Science.gov (United States)

    Krasnokutski, Serge A; Lee, Jung Sup; Yang, Dong-Sheng

    2010-01-28

    Li complexes of adenine, uracil, and thymine were produced by laser vaporization of rods made of Li and nucleobase powders in a metal-cluster beam source and studied by pulsed-field-ionization zero-electron-kinetic-energy (ZEKE) spectroscopy and density functional theory calculations. The ZEKE measurements determined the adiabatic ionization energies of the three neutral complexes and frequencies of several vibrational modes for the metal-adenine and -uracil ions. The measured spectra were compared with spectral simulations to determine the preferred metal binding sites. For adenine, the most stable structure is formed by Li/Li(+) bidentately binding to both the N7 atom of the imidazole ring and the NH(2) group of the pyrimidine ring. For uracil and thymine, the ideal site for Li/Li(+) coordination is the O4 atom. Although it has only a small effect on the geometries of uracil and thymine, lithium coordination forces the rotation of the NH(2) group out of the adenine plane. The adiabatic ionization energies of the three complexes follow the trend of uracil (33910+/-5 cm(-1))>thymine (33386+/-5 cm(-1))>adenine (32240+/-5 cm(-1)), whereas their metal-ligand bond dissociation energies are about the same, (92-97) +/-6 kJ mol(-1). For all three complexes, the neutral bond energies are smaller than those of the corresponding ions due to a weaker electrostatic interaction and stronger electron repulsion.

  9. X-ray absorption spectroscopy using a self-seeded soft X-ray free-electron laser

    OpenAIRE

    Kroll, Thomas; Kern, Jan; Kubin, Markus; Ratner, Daniel; Gul, Sheraz; Fuller, Franklin D.; Löchel, Heike; Krzywinski, Jacek; Lutman, Alberto; Ding, Yuantao; Dakovski, Georgi L.; Moeller, Stefan; Turner, Joshua J.; Alonso-Mori, Roberto; Nordlund, Dennis L.

    2016-01-01

    X-ray free electron lasers (XFELs) enable unprecedented new ways to study the electronic structure and dynamics of transition metal systems. L-edge absorption spectroscopy is a powerful technique for such studies and the feasibility of this method at XFELs for solutions and solids has been demonstrated. However, the required x-ray bandwidth is an order of magnitude narrower than that of self-amplified spontaneous emission (SASE), and additional monochromatization is needed. Here we compare L-...

  10. X-ray absorption spectroscopy using a self-seeded soft X-ray free-electron laser

    OpenAIRE

    Kroll, T.; J. Kern; Kubin, M; Ratner, D.; Gul, S.; Fuller, FD; Löchel, H.; Krzywinski, J.; A. Lutman; Ding, Y.; Dakovski, GL; Moeller, S.; Turner, JJ; Alonso-Mori, R.; Nordlund, DL

    2016-01-01

    © 2016 Optical Society of America. X-ray free electron lasers (XFELs) enable unprecedented new ways to study the electronic structure and dynamics of transition metal systems. L-edge absorption spectroscopy is a powerful technique for such studies and the feasibility of this method at XFELs for solutions and solids has been demonstrated. However, the required x-ray bandwidth is an order of magnitude narrower than that of self-amplified spontaneous emission (SASE), and additional monochromatiz...

  11. Time-resolved photoemission spectroscopy of electronic cooling and localization in CH3NH3PbI3 crystals

    Science.gov (United States)

    Chen, Zhesheng; Lee, Min-i.; Zhang, Zailan; Diab, Hiba; Garrot, Damien; Lédée, Ferdinand; Fertey, Pierre; Papalazarou, Evangelos; Marsi, Marino; Ponseca, Carlito; Deleporte, Emmanuelle; Tejeda, Antonio; Perfetti, Luca

    2017-09-01

    We measure the surface of CH3NH3PbI3 single crystals by making use of two-photon photoemission spectroscopy. Our method monitors the electronic distribution of photoexcited electrons, explicitly discriminating the initial thermalization from slower dynamical processes. The reported results disclose the fast-dissipation channels of hot carriers (0.25 ps), set an upper bound to the surface-induced recombination velocity (solar cells to the theoretical limit.

  12. Ultrabroadband 2D electronic spectroscopy with high-speed, shot-to-shot detection.

    Science.gov (United States)

    Son, Minjung; Mosquera-Vázquez, Sandra; Schlau-Cohen, Gabriela S

    2017-08-07

    Two-dimensional electronic spectroscopy (2DES) is an incisive tool for disentangling excited state energies and dynamics in the condensed phase by directly mapping out the correlation between excitation and emission frequencies as a function of time. Despite its enhanced frequency resolution, the spectral window of detection is limited to the laser bandwidth, which has often hindered the visualization of full electronic energy relaxation pathways spread over the entire visible region. Here, we describe a high-sensitivity, ultrabroadband 2DES apparatus. We report a new combination of a simple and robust setup for increased spectral bandwidth and shot-to-shot detection. We utilize 8-fs supercontinuum pulses generated by gas filamentation spanning the entire visible region (450 - 800 nm), which allows for a simultaneous interrogation of electronic transitions over a 200-nm bandwidth, and an all-reflective interferometric delay system with angled nanopositioner stages achieves interferometric precision in coherence time control without introducing wavelength-dependent dispersion to the ultrabroadband spectrum. To address deterioration of detection sensitivity due to the inherent instability of ultrabroadband sources, we introduce a 5-kHz shot-to-shot, dual chopping acquisition scheme by combining a high-speed line-scan camera and two optical choppers to remove scatter contributions from the signal. Comparison of 2D spectra acquired by shot-to-shot detection and averaged detection shows a 15-fold improvement in the signal-to-noise ratio. This is the first direct quantification of detection sensitivity on a filamentation-based ultrabroadband 2DES apparatus.

  13. Pulsed field ionization electron spectroscopy and molecular structure of aluminum uracil.

    Science.gov (United States)

    Krasnokutski, Serge A; Yang, Dong-Sheng

    2007-10-25

    Al-uracil (Al-C4H4N2O2) was synthesized in a laser-vaporization supersonic molecular beam source and studied with pulsed field ionization-zero electron kinetic energy (ZEKE) photoelectron spectroscopy and density functional theory (DFT). The DFT calculations predicted several low-energy Al-uracil isomers with Al binding to the diketo, keto-enol, and dienol tautomers of uracil. The ZEKE spectroscopic measurements of Al-uracil determined the ionization energy of 43 064(5) cm-1 [or 5.340(6) eV] and a vibrational mode of 51 cm-1 for the neutral complex and several vibrational modes of 51, 303, 614, and 739 cm-1 for the ionized species. Combination of the ZEEK spectrum with the DFT and Franck-Condon factor calculations determined the preferred isomeric structure and electronic states of the Al-uracil complex. This isomer is formed by Al binding to the O4 atom of the diketo tautomer of uracil and has a planar Cs symmetry. The ground electronic states of the neutral and ionized species are 2A' ' and 1A', respectively. The 2A' ' neutral state has a slightly shorter Al-O4 distance than the 1A' ion state. However, the 1A' ion state has stronger metal-ligand binding compared to the 2A' ' state. The increased Al-O4 distance from the 2A' ' state to the 1A' state is attributed to the loss of the pi binding interaction between Al and O4 in the singlet ion state, whereas the increased metal-ligand binding strength is due to the additional charge-dipole interaction in the ion that surpasses the loss of the pi orbital interaction.

  14. Utilizing electron microscopy and spectroscopy methods to understand water structure and water doping

    Science.gov (United States)

    Miller, Lior

    Water is the second most common element in the universe and the most studied material on earth. Most of the studies concerning water are from the fields of chemistry and biology. Hence, the structure of water molecules and short range order and interactions are well characterized and understood. However, the collective arrangement of water molecules and the long range order are still missing. Understanding of this long range order in water is needed, as it is the key to many water activities. To fill this gap, this study utilizes a new direct method for characterization of water in the vapor phase. Water samples from different water types were characterized using electron energy loss spectroscopy (EELS) within a transmission electron microscope (TEM). Prior to characterizing water vapor, the measurement method for in-situ gas analysis was developed using pure gases. Water samples were also characterized using more conventional techniques, including: using cryogenic scanning electron microscopy (Cryo-SEM) in the solid state, after rapid freezing; and using high resolution TEM (HRTEM) and scanning TEM (STEM) after drying. Many other characterization techniques were evaluated but most of them were found to be not suitable, mainly due to detection limits. EELS characterization showed that samples from different water types have different electronic configurations, and they all have structures that are large enough in order to scatter electrons. From cryo SEM characterization it was found that water has nanoparticles inside with a size range of 10-100 nm, and these particles are ~500 nm apart. HRTEM/STEM characterization showed that particles from different water types have different shapes. The presence of particles provide surfaces to support water structures and the difference between the particles can explain the different properties of different water types Using tools and methods that are conventional in materials science for characterization of bulk materials and

  15. Electronic structure of Fe2P(10 1 bar 0) studied by soft X-ray photoelectron spectroscopy and X-ray absorption spectroscopy

    Science.gov (United States)

    Sugizaki, Y.; Motoyama, H.; Edamoto, K.; Ozawa, K.

    2017-10-01

    The electronic structure of Fe2P(10 1 bar 0) has been investigated by photoelectron spectroscopy (PES) and X-ray absorption spectroscopy (XAS). The surface prepared by cycles of Ar+ ion sputtering and annealing at 500-800 °C showed a c(2 × 2) low-energy electron diffraction (LEED) pattern. An Fe 3d-P 3p hybrid band (main band) and a satellite were observed at 0-4 eV and 5-8 eV, respectively, in PES spectra of c(2 × 2) Fe2P(10 1 bar 0). The main band showed a clear cut-off at the Fermi edge, indicating the metallic nature of Fe2P. The satellite intensity showed a resonant maximum around the Fe 3p threshold, suggesting that the satellite is caused through a shake-up process. Three types of surface-shifted components were found in P 2p PES spectra. All the P 2p peaks have symmetric line shapes, while the Fe 2p PES and Fe L-edge XAS spectra have asymmetric line shapes, suggesting that the electronic states around the Fermi level are mostly composed of Fe 3d components. These results suggest that the stabilization of the electronic structure at metal sites through the bonding with P atoms is ineffective on Fe2P(10 1 bar 0), as in the case of Fe2P(0001).

  16. Calibrating the Auger Engineering Radio Array at the Pierre Auger Observatory using an Octocopter

    Energy Technology Data Exchange (ETDEWEB)

    Briechle, Florian; Erdmann, Martin; Krause, Raphael [III. Physikalisches Institut A, RWTH Aachen University (Germany)

    2016-07-01

    With the Auger Engineering Radio Array (AERA) at the Pierre Auger Observatory radio emission of extensive air showers induced by ultra high energy cosmic rays is observed. Characteristics of the primary cosmic ray, e.g., arrival direction, mass or energy, can be measured this way. To produce high quality data, the detector needs to be well understood and calibrated. A useful tool for calibration campaigns is an octocopter. With it, a calibration source can be placed above the array, which makes this a very flexible method useful for different types of calibrations. Special focus is put on the position reconstruction and the position accuracy of the octocopter during the calibration flights. A new optical method using two cameras for these position reconstructions is presented. Results of a measurement campaign in spring 2015 are presented. In this campaign, the sensitivity of the AERA stations as well as timing characteristics were measured. The results of the sensitivity measurement are compared to simulations.

  17. Quasiclassical treatment of the Auger effect in slow ion-atom collisions

    Science.gov (United States)

    Frémont, F.

    2017-09-01

    A quasiclassical model based on the resolution of Hamilton equations of motion is used to get evidence for Auger electron emission following double-electron capture in 150-keV N e10 ++He collisions. Electron-electron interaction is taken into account during the collision by using pure Coulombic potential. To make sure that the helium target is stable before the collision, phenomenological potentials for the electron-nucleus interactions that simulate the Heisenberg principle are included in addition to the Coulombic potential. First, single- and double-electron captures are determined and compared with previous experiments and theories. Then, integration time evolution is calculated for autoionizing and nonautoionizing double capture. In contrast with single capture, the number of electrons originating from autoionization slowly increases with integration time. A fit of the calculated cross sections by means of an exponential function indicates that the average lifetime is 4.4 ×10-3a .u . , in very good agreement with the average lifetime deduced from experiments and a classical model introduced to calculate individual angular momentum distributions. The present calculation demonstrates the ability of classical models to treat the Auger effect, which is a pure quantum effect.

  18. Antiproton–to–electron mass ratio determined by two-photon laser spectroscopy of antiprotonic helium atoms

    Directory of Open Access Journals (Sweden)

    Sótér A.

    2014-03-01

    Full Text Available The ASACUSA collaboration of CERN has recently carried out two-photon laser spectroscopy of antiprotonic helium atoms. Three transition frequencies were determined with fractional precisions of 2.3–5 parts in 109. By comparing the results with three-body QED calculations, the antiproton-to-electron mass ratio was determined as 1836.1526736(23.

  19. Use of spin labels to study membrane proteins by high-frequency electron nuclear double resonance spectroscopy

    NARCIS (Netherlands)

    Orlinkskii, S.B.; Borovykh, I.V.; Zielke, V.; Steinhoff, H.J.

    2007-01-01

    The applicability of spin labels to study membrane proteins by high-frequency electron nuclear double resonance spectroscopy is demonstrated. With the use of bacteriorhodopsin embedded in a lipid membrane as an example, the spectra of protons of neighboring amino acids are recorded, electric field

  20. Characterization of Al2O3-Supported Manganese Oxides by Electron Spin Resonance and Diffuse Reflectance Spectroscopy

    NARCIS (Netherlands)

    Kijlstra, W.S.; Poels, E.K.; Bliek, A.; Weckhuysen, B.M.; Schoonheydt, R.A.

    1996-01-01

    Alumina-supported manganese oxides, used as catalysts for the selective catalytic reduction of NO, were characterized by combined electron spin resonance and diffuse reflectance spectroscopies. Upon impregnation of the acetate precursor solution, the [Mn(H2O)6]^2+ complex interacts strongly with

  1. Charge deep-level transient spectroscopy study of high-energy-electron-beam-irradiated hydrogenated amorphous silicon

    NARCIS (Netherlands)

    Klaver, A.; Nádaždy, V.; Zeman, M.; Swaaiij, R.A.C.M.M.

    2006-01-01

    We present a study of changes in the defect density of states in hydrogenated amorphous silicon (a-Si:H) due to high-energy electron irradiation using charged deep-level transient spectroscopy. It was found that defect states near the conduction band were removed, while in other band gap regions the

  2. Comparing the photophysics of the two forms of the Orange Carotenoid Protein using 2D electronic spectroscopy

    Directory of Open Access Journals (Sweden)

    Mathies R.A.

    2013-03-01

    Full Text Available Broadband two-dimensional electronic spectroscopy is applied to investigate the photophysics of the photoactive orange carotenoid protein, which is involved in nonphotochemical quenching in cyanobacteria. Differences in dynamics between the light and dark forms arise from the different structure of the carotenoid in the protein pocket, with consequences for the biological role of the two forms.

  3. 30 CFR 819.21 - Auger mining: Protection of underground mining.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 3 2010-07-01 2010-07-01 false Auger mining: Protection of underground mining. 819.21 Section 819.21 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT... STANDARDS-AUGER MINING § 819.21 Auger mining: Protection of underground mining. Auger holes shall not extend...

  4. Soft X-ray Spectroscopy Study of the Electronic Structure of Oxidized and Partially Oxidized Magnetite Nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Gilbert, Benjamin; Katz, Jordan E.; Denlinger, Jonathan D.; Yin, Yadong; Falcone, Roger; Waychunas, Glenn A.

    2010-10-24

    The crystal structure of magnetite nanoparticles may be transformed to maghemite by complete oxidation, but under many relevant conditions the oxidation is partial, creating a mixed-valence material with structural and electronic properties that are poorly characterized. We used X-ray diffraction, Fe K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy, and soft X-ray absorption and emission spectroscopy to characterize the products of oxidizing uncoated and oleic acid-coated magnetite nanoparticles in air. The oxidization of uncoated magnetite nanoparticles creates a material that is structurally and electronically indistinguishable from maghemite. By contrast, while oxidized oleic acid-coated nanoparticles are also structurally indistinguishable from maghemite, Fe L-edge spectroscopy revealed the presence of interior reduced iron sites even after a 2-year period. We used X-ray emission spectroscopy at the O K-edge to study the valence bands (VB) of the iron oxide nanoparticles, using resonant excitation to remove the contributions from oxygen atoms in the ligands and from low-energy excitations that obscured the VB edge. The bonding in all nanoparticles was typical of maghemite, with no detectable VB states introduced by the long-lived, reduced-iron sites in the oleic acid-coated sample. However, O K-edge absorption spectroscopy observed a 0.2 eV shift in the position of the lowest unoccupied states in the coated sample, indicating an increase in the semiconductor band gap relative to bulk stoichiometric maghemite that was also observed by optical absorption spectroscopy. The results show that the ferrous iron sites within ferric iron oxide nanoparticles coated by an organic ligand can persist under ambient conditions with no evidence of a distinct interior phase and can exert an effect on the global electronic and optical properties of the material. This phenomenon resembles the band gap enlargement caused by electron accumulation in the

  5. Spectroscopie du Furanne et du Thiophene Par Diffusion Inelastique D'electrons

    Science.gov (United States)

    Lotfi, Said

    Nous avons etudie les molecules de furanne ( rm C_4H_4O) et de thiophene (rm C_4H_4O) au moyen de la spectroscopie de diffusion inelastique d'electrons. Pour (rm C_4H_4O), les spectres realises dans differentes conditions d'energie d'impact et d'angle de diffusion contiennent des singularites ou des families de pics correspondant a: (1) des vibrations de l'etat fondamental dans le domaine 0-0.5 eV, (2) des etats triplets ^3 B_1 et ^3 A_1 qui dominent la region 3-5.5 eV, (3) des etats de valences, entre 5 et 10 eV, dont certains son accompagnes de progressions vibrationnelles, soit ~ A _1B_2, ~ B ^1A_1 et ~ C ^1A_1, (4) toujours entre 5 et 10 eV, deux series de Ryhdberg (rm 1a_2to nda_2 et rm 1a_2to npb_2) qui convergent vers la premiere limite d'ionisation de la molecule, avec une progression vibrationnelle associee au mdoe nu_4 pour la seconde, et une troisieme serie (rm 2b_1to nsa_1 ) convergent vers la seconde limite d'ionisation accompagnee de la progression de mode nu _1. Pour rm C_4H_4S, nos spectres presentent les memes etats de vibration et les memes etats triplets que pour rm C_4H _4O. Nous avons releve egalement, dans la region de 5 a 10 eV, des etats de valence ~ A ^1A_1 (ou ~ A ^1B_2), ~ B ^1A_1 (ou ~ B ^1B _2) et ~ C ^1A_1 (ou ~ C ^1B_2). Pour la premiere fois, par la spectroscopie de diffusion inelastique d'electrons, de nombreux pics ont ete identifies et attribues, dans le cadre de ce travail. Il s'agit, notamment, des etats de vibration de l'etat electronique fondamental de ces molecules et egalement de certains etats de Rydberg dans le cas du furanne.

  6. Dependence of the electron work function change of the rhodium (100) face on the order of oxygen and hydrogen adsorption

    Energy Technology Data Exchange (ETDEWEB)

    Kalish, T.V.; Belyaeva, M.E.

    1988-03-01

    It has been shown that the order of hydrogen and oxygen adsorption on rhodium determines the course of the adsorbates interaction. Changes in electron work function of the rhodium (100) face which occur as a function of time during hydrogen adsorption on a surface with preadsorbed oxygen was studied along with changes in the electron work function during adsorption of hydrogen and oxygen. The electron work function was determined by photoelectric emission. Gas adsorption occurred at room temperature, the gas phase composition was determined with an omegatron, and Auger spectroscopy was used to check the cleanliness of the original surface.

  7. Discretization of electronic states in large InAsP/InP multilevel quantum dots probed by scanning tunneling spectroscopy.

    Science.gov (United States)

    Fain, B; Robert-Philip, I; Beveratos, A; David, C; Wang, Z Z; Sagnes, I; Girard, J C

    2012-03-23

    The topography and the electronic structure of InAsP/InP quantum dots are probed by cross-sectional scanning tunneling microscopy and spectroscopy. The study of the local density of states in such large quantum dots confirms the discrete nature of the electronic levels whose wave functions are measured by differential conductivity mapping. Because of their large dimensions, the energy separation between the discrete electronic levels is low, allowing for quantization in both the lateral and growth directions as well as the observation of the harmonicity of the dot lateral potential.

  8. The adsorption of fluor-carbon complexes on GaAs(110) studied by electron energy loss spectroscopy

    Science.gov (United States)

    Förster, A.; Spitzer, A.; Lüth, H.

    1986-06-01

    The room temperature adsorption of CF 3COOH, CH 3COOH and CO on cleaved GaAs(110) surfaces has been studied by vibrational electron energy loss spectroscopy (HRELS), second derivative electron energy spectroscopy (ELS) and electron diffraction (LEED). CO does not adsorb on the GaAs surfaces in measurable quantities. Acetic acid CH 3COOH is dissociatively adsorbed as an acetate bonded to Ga surface atoms with the split-off hydrogen on As surface atoms. The fluorated acid CF 3COOH decomposes via an acetate intermediate CF 3COO into active CF 3 groups which adsorb on Ga surface atoms. The split-off hydrogen sticks to surface As atoms while the generated CO 2 desorbs. The adsorption models are consistent with the LEED c(2×2) superstructure observed after saturated adsorption of both acids.

  9. Hyperfine interaction of Er3+ ions in Y2SiO5 : An electron paramagnetic resonance spectroscopy study

    Science.gov (United States)

    Guillot-Noël, O.; Goldner, Ph.; Du, Y. Le; Baldit, E.; Monnier, P.; Bencheikh, K.

    2006-12-01

    Electron paramagnetic resonance (EPR) spectroscopy of rare earth ions in crystals is a powerful tool to analyze the hyperfine structure of the rare earth ground state. This can be useful for coherent spectroscopy and quantum information applications where the hyperfine structure of the electronic levels is used. In this work, we give a detailed analysis of the hyperfine structure of the ground state [I15/24(0)] of Er3+ ions in Y2SiO5 . The electronic Zeeman, hyperfine, and quadrupole matrices are obtained from angular variations of the magnetic field in three orthogonal crystal planes. An excellent agreement is obtained between experimental and simulated magnetic field positions and relative intensities of EPR lines.

  10. The substrate effect in electron energy-loss spectroscopy of localized surface plasmons in gold and silver nanoparticles

    DEFF Research Database (Denmark)

    Kadkhodazadeh, Shima; Christensen, Thomas; Beleggia, Marco

    2017-01-01

    Electron energy-loss spectroscopy (EELS) has become increasingly popular for detailed characterization of plasmonic nanostructures, owing to the unparalleled spatial resolution of this technique. The typical setup in EELS requires nanoparticles to be supported on thin substrates. However, as in o......Electron energy-loss spectroscopy (EELS) has become increasingly popular for detailed characterization of plasmonic nanostructures, owing to the unparalleled spatial resolution of this technique. The typical setup in EELS requires nanoparticles to be supported on thin substrates. However......, as in optical measurements, the substrate material can modify the acquired signal. Here, we have investigated how the EELS signal recorded from supported silver and gold spheroidal nanoparticles at different electron beam impact parameter positions is affected by the choice of a dielectric substrate material...

  11. Discrimination of Apple Liqueurs (Nalewka) Using a Voltammetric Electronic Tongue, UV-Vis and Raman Spectroscopy.

    Science.gov (United States)

    Śliwińska, Magdalena; Garcia-Hernandez, Celia; Kościński, Mikołaj; Dymerski, Tomasz; Wardencki, Waldemar; Namieśnik, Jacek; Śliwińska-Bartkowiak, Małgorzata; Jurga, Stefan; Garcia-Cabezon, Cristina; Rodriguez-Mendez, Maria Luz

    2016-10-09

    The capability of a phthalocyanine-based voltammetric electronic tongue to analyze strong alcoholic beverages has been evaluated and compared with the performance of spectroscopic techniques coupled to chemometrics. Nalewka Polish liqueurs prepared from five apple varieties have been used as a model of strong liqueurs. Principal Component Analysis has demonstrated that the best discrimination between liqueurs prepared from different apple varieties is achieved using the e-tongue and UV-Vis spectroscopy. Raman spectra coupled to chemometrics have not been efficient in discriminating liqueurs. The calculated Euclidean distances and the k-Nearest Neighbors algorithm (kNN) confirmed these results. The main advantage of the e-tongue is that, using PLS-1, good correlations have been found simultaneously with the phenolic content measured by the Folin-Ciocalteu method (R² of 0.97 in calibration and R² of 0.93 in validation) and also with the density, a marker of the alcoholic content method (R² of 0.93 in calibration and R² of 0.88 in validation). UV-Vis coupled with chemometrics has shown good correlations only with the phenolic content (R² of 0.99 in calibration and R² of 0.99 in validation) but correlations with the alcoholic content were low. Raman coupled with chemometrics has shown good correlations only with density (R² of 0.96 in calibration and R² of 0.85 in validation). In summary, from the three holistic methods evaluated to analyze strong alcoholic liqueurs, the voltammetric electronic tongue using phthalocyanines as sensing elements is superior to Raman or UV-Vis techniques because it shows an excellent discrimination capability and remarkable correlations with both antioxidant capacity and alcoholic content-the most important parameters to be measured in this type of liqueurs.

  12. Discrimination of Apple Liqueurs (Nalewka Using a Voltammetric Electronic Tongue, UV-Vis and Raman Spectroscopy

    Directory of Open Access Journals (Sweden)

    Magdalena Śliwińska

    2016-10-01

    Full Text Available The capability of a phthalocyanine-based voltammetric electronic tongue to analyze strong alcoholic beverages has been evaluated and compared with the performance of spectroscopic techniques coupled to chemometrics. Nalewka Polish liqueurs prepared from five apple varieties have been used as a model of strong liqueurs. Principal Component Analysis has demonstrated that the best discrimination between liqueurs prepared from different apple varieties is achieved using the e-tongue and UV-Vis spectroscopy. Raman spectra coupled to chemometrics have not been efficient in discriminating liqueurs. The calculated Euclidean distances and the k-Nearest Neighbors algorithm (kNN confirmed these results. The main advantage of the e-tongue is that, using PLS-1, good correlations have been found simultaneously with the phenolic content measured by the Folin–Ciocalteu method (R2 of 0.97 in calibration and R2 of 0.93 in validation and also with the density, a marker of the alcoholic content method (R2 of 0.93 in calibration and R2 of 0.88 in validation. UV-Vis coupled with chemometrics has shown good correlations only with the phenolic content (R2 of 0.99 in calibration and R2 of 0.99 in validation but correlations with the alcoholic content were low. Raman coupled with chemometrics has shown good correlations only with density (R2 of 0.96 in calibration and R2 of 0.85 in validation. In summary, from the three holistic methods evaluated to analyze strong alcoholic liqueurs, the voltammetric electronic tongue using phthalocyanines as sensing elements is superior to Raman or UV-Vis techniques because it shows an excellent discrimination capability and remarkable correlations with both antioxidant capacity and alcoholic content—the most important parameters to be measured in this type of liqueurs.

  13. Direct rate assessment of laccase catalysed radical formation in lignin by electron paramagnetic resonance spectroscopy.

    Science.gov (United States)

    Munk, Line; Andersen, Mogens Larsen; Meyer, Anne S

    2017-11-01

    Laccases (EC 1.10.3.2) catalyse removal of an electron and a proton from phenolic hydroxyl groups, including phenolic hydroxyls in lignins, to form phenoxy radicals during reduction of O2. We employed electron paramagnetic resonance spectroscopy (EPR) for real time measurement of such catalytic radical formation activity on three types of lignin (two types of organosolv lignin, and a lignin rich residue from wheat straw hydrolysis) brought about by two different fungal laccases, derived from Trametes versicolor (Tv) and Myceliophthora thermophila (Mt), respectively. Laccase addition to suspensions of the individual lignin samples produced immediate time and enzyme dose dependent increases in intensity in the EPR signal with g-values in the range 2.0047-2.0050 allowing a direct quantitative monitoring of the radical formation and thus allowed laccase enzyme kinetics assessment on lignin. The experimental data verified that the laccases acted upon the insoluble lignin substrates in the suspensions. When the action on the lignin substrates of the two laccases were compared on equal enzyme dosage levels (by activity units on syringaldazine) the Mt laccase exerted a significantly faster radical formation than the Tv laccase on all three types of lignin substrates. When comparing the equal laccase dose rates on the three lignin substrates the enzymatic radical formation rate on the wheat straw lignin residue was consistently higher than those of the organosolv lignins. The pH-temperature optimum for the radical formation rate in organosolv lignin was determined by response surface methodology to pH 4.8, 33°C and pH 5.8, 33°C for the Tv laccase and the Mt laccase, respectively. The results verify direct radical formation action of fungal laccases on lignin without addition of mediators and the EPR methodology provides a new type of enzyme assay of laccases on lignin. Copyright © 2017 Elsevier Inc. All rights reserved.

  14. A combined photoelectron spectroscopy and relativistic ab initio studies of the electronic structures of UFO and UFO-

    Science.gov (United States)

    Roy, Soumendra K.; Jian, Tian; Lopez, Gary V.; Li, Wei-Li; Su, Jing; Bross, David H.; Peterson, Kirk A.; Wang, Lai-Sheng; Li, Jun

    2016-02-01

    The observation of the gaseous UFO- anion is reported, which is investigated using photoelectron spectroscopy and relativisitic ab initio calculations. Two strong photoelectron bands are observed at low binding energies due to electron detachment from the U-7sσ orbital. Numerous weak detachment bands are also observed due to the strongly correlated U-5f electrons. The electron affinity of UFO is measured to be 1.27(3) eV. High-level relativistic quantum chemical calculations have been carried out on the ground state and many low-lying excited states of UFO to help interpret the photoelectron spectra and understand the electronic structure of UFO. The ground state of UFO- is linear with an O-U-F structure and a 3H4 spectral term derived from a U 7sσ25fφ15fδ1 electron configuration, whereas the ground state of neutral UFO has a 4H7/2 spectral term with a U 7sσ15fφ15fδ1 electron configuration. Strong electron correlation effects are found in both the anionic and neutral electronic configurations. In the UFO neutral, a high density of electronic states with strong configuration mixing is observed in most of the scalar relativistic and spin-orbit coupled states. The strong electron correlation, state mixing, and spin-orbit coupling of the electronic states make the excited states of UFO very challenging for accurate quantum chemical calculations.

  15. Nanoscale Phase Separation and Lattice Complexity in VO2: The Metal–Insulator Transition Investigated by XANES via Auger Electron Yield at the Vanadium L23-Edge and Resonant Photoemission

    Directory of Open Access Journals (Sweden)

    Augusto Marcelli

    2017-12-01

    Full Text Available Among transition metal oxides, VO2 is a particularly interesting and challenging correlated electron material where an insulator to metal transition (MIT occurs near room temperature. Here we investigate a 16 nm thick strained vanadium dioxide film, trying to clarify the dynamic behavior of the insulator/metal transition. We measured (resonant photoemission below and above the MIT transition temperature, focusing on heating and cooling effects at the vanadium L23-edge using X-ray Absorption Near-Edge Structure (XANES. The vanadium L23-edges probe the transitions from the 2p core level to final unoccupied states with 3d orbital symmetry above the Fermi level. The dynamics of the 3d unoccupied states both at the L3- and at the L2-edge are in agreement with the hysteretic behavior of this thin film. In the first stage of the cooling, the 3d unoccupied states do not change while the transition in the insulating phase appears below 60 °C. Finally, Resonant Photoemission Spectra (ResPES point out a shift of the Fermi level of ~0.75 eV, which can be correlated to the dynamics of the 3d// orbitals, the electron–electron correlation, and the stability of the metallic state.

  16. A study of Roman glass by reflectance and electron paramagnetic resonance spectroscopies

    Science.gov (United States)

    Mirti, P.; Ferrari, R. P.; Laurenti, E.; Casoli, A.

    1993-08-01

    Reflectance and electron paramagnetic resonance (EPR) spectroscopies were used to study 25 fragments of Roman glass. Colour coordinates were used for an unbiased classification of the glasses in colour groups, which accounted for the presence of blue, blue-green, green, yellow-green, yellow and purple samples. Reflectance spectra were recorded in the 250-2500 nm wavelength range and showed absorption bands characteristic of Fe II, Fe III and Mn III ions; furthermore, Co II and Cu II bands were observed in the spectra of the blue glasses. A decrease of the absorbance ratio of Fe II to Fe III ions was observed moving from blue-green to green and yellow-green glasses; however, yellow fragments still proved to be reduced glasses. EPR spectra displayed the characteristic patterns of Fe III and Mn II ions, with g-values in the 2-5 interval and spectral features depending on the relative content of the two elements. The characteristic pattern of the V IV ion ( g ≈ 2) and signals due to the formation of iron-sulphur complexes ( g ≈ 6) appeared in the spectrum of a dark yellow glass, recorded at 77 K.

  17. Ultrabroadband 2D electronic spectroscopy as a tool for direct visualization of pathways of energy flow

    Science.gov (United States)

    Son, Minjung; Schlau-Cohen, Gabriela S.

    2017-08-01

    Two-dimensional electronic spectroscopy (2DES) has emerged as an incisive tool for mapping out energy relaxation pathways in complex molecular systems by determining correlation maps between the excitation and emission frequencies. Its enhanced spectral as well as temporal resolution offer new insights into coupling and energy transfer between closely-spaced energy states, which are often hidden in a one-dimensional transient spectrum. However, a major drawback of the current 2DES technique is that the spectral window of detection is directly limited to the laser bandwidth used, which leads to an incomplete visualization of the full energy landscape of the system. As a solution to this limitation, we present an ultrabroadband 2DES apparatus utilizing a 8-fs, 185-nm bandwidth supercontinuum that covers the entire visible region. We demonstrate the utility of our setup by measuring the 2D spectra of laser dyes absorbing at different regions of the laser spectrum, and the major light-harvesting complex of spinach.

  18. Electron-energy-loss spectroscopy on group-III nitrides and transition- metal oxides

    CERN Document Server

    Niessner, W

    2000-01-01

    A main topic represent electron-energy-loss spectroscopy (EELS) studies of the group-III nitrides AlN, GaN, InN, as well as their mixing systems Al sub x Ga sub 1 sub - sub x N, In sub x Ga sub 1 sub - sub x N. In EELS measurements with excitation energies above 1 keV clear collective excitations in AlN at 21 eV and in GaN at 15 eV were observed. In the mixing system Al sub x Ga sub 1 sub - sub x M a 2-mode behaviour is observed. Up to x=0.2 a GaN-like excitation remains preserved, while from x=0.44 the eigenfrequency of a AlN-like resonance shifts continuously. With vanadium dioxide a d sup 1 transition metal oxide was studied, which passes at 68 C a semiconductor-metal transition. In the EELS valence band spectra beside band transitions from the O2p subsigma and O2p subpi band an intense signal with a loss energy of 1 eV occurs. EELS studies on W- and F-doped VO sub 2 show, that it deals with a band transition from the V3d into the pd subpi band. EELS studies were for the first time also performed at lead t...

  19. Mode Coupling in Plasmonic Heterodimers Probed with Electron Energy Loss Spectroscopy.

    Science.gov (United States)

    Flauraud, Valentin; Bernasconi, Gabriel D; Butet, Jérémy; Alexander, Duncan T L; Martin, Olivier J F; Brugger, Jürgen

    2017-04-25

    While plasmonic antennas composed of building blocks made of the same material have been thoroughly studied, recent investigations have highlighted the unique opportunities enabled by making compositionally asymmetric plasmonic systems. So far, mainly heterostructures composed of nanospheres and nanodiscs have been investigated, revealing opportunities for the design of Fano resonant nanostructures, directional scattering, sensing and catalytic applications. In this article, an improved fabrication method is reported that enables precise tuning of the heterodimer geometry, with interparticle distances made down to a few nanometers between Au-Ag and Au-Al nanoparticles. A wide range of mode energy detuning and coupling conditions are observed by near field hyperspectral imaging performed with electron energy loss spectroscopy, supported by full wave analysis numerical simulations. These results provide direct insights into the mode hybridization of plasmonic heterodimers, pointing out the influence of each dimer constituent in the overall electromagnetic response. By relating the coupling of nondipolar modes and plasmon-interband interaction with the dimer geometry, this work facilitates the development of plasmonic heterostructures with tailored responses, beyond the possibilities offered by homodimers.

  20. Characterization of self-assembling copolymers in aqueous solutions using Electron Paramagnetic Resonance and Fluorescence spectroscopy.

    Science.gov (United States)

    Beghein, N; Rouxhet, L; Dinguizli, M; Brewster, M E; Ariën, A; Préat, V; Habib, J L; Gallez, B

    2007-02-12

    Electron Paramagnetic Resonance and fluorescence spectroscopy have been used to determine the micropolarity and microviscosity of self-assembling systems based on mmePEG-p(CL-co-TMC) having different PEG chain lengths and different CL/TMC ratios and PEG/MOG/SA (45/5/50) polymers with different PEG chain lengths. Four reporter probes have been used: two spin probes, 16-doxyl stearic acid and 5-doxylstearic acid, and two fluorescent probes, pyrene and 1,3-bis(1-pyrenyl) propane (P3P). We found that the micelles based on mmePEG-p(CL-co-TMC) polymers are of a biphasic nature. The micelles are made of a hydrophilic corona with low viscosity while the core of the micelle is more hydrophobic and more viscous. The outer shell is made up of PEG chains, the hydrophobic part of the chains making the core. The partial hydration of the shell seems to lead to a looser chain network than that associated with deeper domains in the micelles. By contrast, in micelles composed of PEG/MOG/SA, there is no clear domain separation. This is consistent with a spatial configuration of random polymeric chains forming a loose network. In these micelles, the microviscosity is low and the hydrophobicity is high.

  1. Alpha and conversion electron spectroscopy of {sup 238,239}Pu and {sup 241}Am and alpha-conversion electron coincidence measurements

    Energy Technology Data Exchange (ETDEWEB)

    Dion, Michael P., E-mail: michael.dion@pnnl.gov; Miller, Brian W.; Warren, Glen A.

    2016-09-11

    A technique to determine the isotopic constituents of a mixed actinide sample has been proposed by a coincident alpha-conversion electron measurement. This presents a unique signature to allow the unfolding of isotopes that possess overlapping alpha particle energy and reduce backgrounds of an unseparated sample. The work presented here are results of conversion electron spectroscopy of {sup 241}Am, {sup 238}Pu and {sup 239}Pu using a dual-stage peltier-cooled 25 mm{sup 2} silicon drift detector and alpha spectroscopy with a passivated ion implanted planar silicon detector. The conversion electron spectra were evaluated from 20–55 keV based on fits to the dominant conversion electron emissions, which allowed the relative conversion electron emission intensities to be determined. These measurements provide crucial singles spectral information and calibration to aid in the coincident measurement approach. Furthermore, an alpha-conversion electron spectrometer was assembled using the silicon based detectors described and results of a coincident spectrum analysis is reported for {sup 241}Am.

  2. Deep levels in as-grown and electron-irradiated n-type GaN studied by deep level transient spectroscopy and minority carrier transient spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Duc, Tran Thien [Department of Physics, Chemistry and Biology (IFM), Linköping University, S-581 83 Linköping (Sweden); School of Engineering Physics, Hanoi University of Science and Technology, 1 Dai Co Viet Road, Hanoi (Viet Nam); Pozina, Galia; Son, Nguyen Tien; Kordina, Olof; Janzén, Erik; Hemmingsson, Carl [Department of Physics, Chemistry and Biology (IFM), Linköping University, S-581 83 Linköping (Sweden); Ohshima, Takeshi [Japan Atomic Energy Agency (JAEA), Takasaki, Gunma 370-1292 (Japan)

    2016-03-07

    Development of high performance GaN-based devices is strongly dependent on the possibility to control and understand defects in material. Important information about deep level defects is obtained by deep level transient spectroscopy and minority carrier transient spectroscopy on as-grown and electron irradiated n-type bulk GaN with low threading dislocation density produced by halide vapor phase epitaxy. One hole trap labelled H1 (E{sub V} + 0.34 eV) has been detected on as-grown GaN sample. After 2 MeV electron irradiation, the concentration of H1 increases and at fluences higher than 5 × 10{sup 14 }cm{sup −2}, a second hole trap labelled H2 is observed. Simultaneously, the concentration of two electron traps, labelled T1 (E{sub C} – 0.12 eV) and T2 (E{sub C} – 0.23 eV), increases. By studying the increase of the defect concentration versus electron irradiation fluence, the introduction rate of T1 and T2 using 2 MeV- electrons was determined to be 7 × 10{sup −3 }cm{sup −1} and 0.9 cm{sup −1}, respectively. Due to the low introduction rate of T1, it is suggested that the defect is associated with a complex. The high introduction rate of trap H1 and T2 suggests that the defects are associated with primary intrinsic defects or complexes. Some deep levels previously observed in irradiated GaN layers with higher threading dislocation densities are not detected in present investigation. It is therefore suggested that the absent traps may be related to primary defects segregated around dislocations.

  3. Two-dimensional electronic spectroscopy with double modulation lock-in detection: enhancement of sensitivity and noise resistance.

    Science.gov (United States)

    Augulis, Ramūnas; Zigmantas, Donatas

    2011-07-04

    In many potential applications of two-dimensional (2D) electronic spectroscopy the excitation energies per pulse are strictly limited, while the samples are strongly scattering. We demonstrate a technique, based on double-modulation of incident laser beams with mechanical choppers, which can be implemented in almost any non-collinear four wave mixing scheme including 2D spectroscopy setup. The technique virtually eliminates artifacts or "ghost" signals in 2D spectra, which arise due to scattering and accumulation of long-lived species. To illustrate the advantages of the technique, we show a comparison of porphyrin J-aggregate 2D spectra obtained with different methods following by discussion.

  4. To the application of the emission Mössbauer and positron annihilation spectroscopies for detection of carcinogens

    Science.gov (United States)

    Bokov, A. V.; Byakov, V. M.; Kulikov, L. A.; Perfiliev, Yu. D.; Stepanov, S. V.

    2017-11-01

    Being the main cause of cancer, almost all chemical carcinogens are strong electrophiles, that is, they have a high affinity for the electron. We have shown that positron annihilation lifetime spectroscopy (PALS) is able to detect chemical carcinogens by their inhibition of positronium (Ps) formation in liquid media. Electrophilic carcinogens intercept thermalized track electrons, which are precursors of Ps, and as a result, when they are present Ps atom does not practically form. Available biophysical data seemingly indicate that frozen solutions model better an intracellular medium than the liquid ones. So it is reasonable to use emission Mössbauer spectroscopy (EMS) to detect chemical carcinogens, measuring the yield of 57Fe2+ions formed in reactions of Auger electrons and other secondary electrons they produced with 57Fe3+. These reactions are similar to the Ps formation process in the terminal part the positron track: e++ e- =>Ps. So EMS and PALS are complementary methods for detection of carcinogenic compounds.

  5. 30 CFR 77.1505 - Auger holes; blocking.

    Science.gov (United States)

    2010-07-01

    ... Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR COAL MINE SAFETY AND HEALTH MANDATORY SAFETY STANDARDS, SURFACE COAL MINES AND SURFACE WORK AREAS OF UNDERGROUND COAL MINES Auger Mining... material before they are abandoned. ...

  6. The Surface Detector System of the Pierre Auger Observatory

    Energy Technology Data Exchange (ETDEWEB)

    Allekotte, I.; Barbosa, A.F.; Bauleo, P.; Bonifazi, C.; Civit, B.; Escobar, C.O.; Garcia, B.; Guedes, G.; Gomez Berisso, M.; Harton, J.L.; Healy, M.; /Cuyo U. /Buenos Aires, CONICET /Natl. Tech. U., San Rafael /Campinas State U. /UEFS, Feira de Santana /Bahia U. /BUAP, Puebla /Santiago de Compostela U. /Fermilab /UCLA /Colorado State U.

    2007-11-01

    The Pierre Auger Observatory is designed to study cosmic rays with energies greater than 10{sup 19} eV. Two sites are envisaged for the observatory, one in each hemisphere, for complete sky coverage. The southern site of the Auger Observatory, now approaching completion in Mendoza, Argentina, features an array of 1600 water-Cherenkov surface detector stations covering 3000 km{sup 2}, together with 24 fluorescence telescopes to record the air shower cascades produced by these particles. The two complementary detector techniques together with the large collecting area form a powerful instrument for these studies. Although construction is not yet complete, the Auger Observatory has been taking data stably since January 2004 and the first physics results are being published. In this paper we describe the design features and technical characteristics of the surface detector stations of the Pierre Auger Observatory.

  7. The surface detector system of the Pierre Auger Observatory

    Energy Technology Data Exchange (ETDEWEB)

    Allekotte, I. [Instituto Balseiro and Centro Atomico Bariloche (U.N. Cuyo and CNEA, CONICET), 8400 Bariloche (Argentina)], E-mail: ingo@cab.cnea.gov.ar; Barbosa, A.F. [CBPF, Rua Xavier Sigaud 150, Rio de Janeiro (Brazil); Bauleo, P. [Colorado State University, Fort Collins, CO 80523 (United States); Bonifazi, C. [CBPF, Rua Xavier Sigaud 150, Rio de Janeiro (Brazil); Civit, B. [Universidad Tecnologica Nacional Regional Mendoza, Mendoza (Argentina); Escobar, C.O. [Departamento de Raios Cosmicos, Instituto de Fisica, Universidade Estadual de Campinas, CP 6165, 13084-971, Campinas SP (Brazil); Garcia, B. [Universidad Tecnologica Nacional Regional Mendoza, Mendoza (Argentina); Guedes, G. [Universidade Estadual de Feira de Santana (UEFS), Av. Universitaria Km 03 da BR 116, Campus Universitario, 44031-460 Feira de Santana BA (Brazil); Gomez Berisso, M. [Instituto Balseiro and Centro Atomico Bariloche (U.N. Cuyo and CNEA, CONICET), 8400 Bariloche (Argentina); Harton, J.L. [Colorado State University, Fort Collins, CO 80523 (United States); Healy, M. [Department of Physics and Astronomy, University of California, Los Angeles (UCLA), Los Angeles, CA 90095 (United States); Kaducak, M.; Mantsch, P.; Mazur, P.O.; Newman-Holmes, C. [Fermi National Accelerator Laboratory Batavia, IL (United States); Pepe, I. [Universidade Federal da Bahia, Campus de Odina, 40210-340 Salvador BA (Brazil); Rodriguez-Cabo, I. [Dpto. Fisica de Particulas, Universidad de Santiago de Compostela, 15706 Santiago de Compostela (Spain); Salazar, H. [Benemerita Universidad Autonoma de Puebla (BUAP), Ap. Postal J-48, 72500 Puebla, Puebla (Mexico); Smetniansky-De Grande, N. [Laboratorio Tandar, Comision Nacional de Energia Atomica and CONICET, Av. Gral. Paz 1499 (1650) San Martin, Buenos Aires (Argentina); Warner, D. [Colorado State University, Fort Collins, CO 80523 (United States)

    2008-03-01

    The Pierre Auger Observatory is designed to study cosmic rays with energies greater than 10{sup 19}eV. Two sites are envisaged for the observatory, one in each hemisphere, for complete sky coverage. The southern site of the Auger Observatory, now approaching completion in Mendoza, Argentina, features an array of 1600 water-Cherenkov surface detector stations covering 3000km{sup 2}, together with 24 fluorescence telescopes to record the air shower cascades produced by these particles. The two complementary detector techniques together with the large collecting area form a powerful instrument for these studies. Although construction is not yet complete, the Auger Observatory has been taking data stably since January 2004 and the first physics results are being published. In this paper we describe the design features and technical characteristics of the surface detector stations of the Pierre Auger Observatory.

  8. Holographic Spectroscopy for Rapid Electron Bunch Analysis: Development of an Instrument with THZ Resolved Optical Gating

    Energy Technology Data Exchange (ETDEWEB)

    Sievers, Albert

    2011-10-28

    The main thrust of our project was to apply the concepts of holographic spectroscopy, developed earlier in the visible and near IR spectral regions for satellite mapping, to the THz region in order to measure the spectral signature of the coherent radiation emanating from a relativistic electron bunch to obtain the bunch length itself. There were four major discoveries. (1) In the course of this ground-breaking work we developed and built the first static THz interferometer suitable for the realization of such a holographic Fourier transform spectrometer. Experimental tests and analysis of the observed results have provided the necessary foundation for future development of THz detector arrays optimized for spectroscopic applications. (2) Since such detectors do not exist at the present time our next effort was to find an alternative approach. We explored the electro-optic (EO) detection of the THz pulse using the short pulse of a visible diode laser synchronized to the bunch with the long-term goal aimed at single bunch measurement capability. The main hurdle was found to be the parasitic scattering of the diode radiation in the EO medium. By using the optical Fourier transform of the THz interference pattern the effects of this background were suppressed enough to obtain the spectrum using multiple shot acquisition. During our experiments at the FLASH facility at DESY we determined that for single bunch measurement capability the diode laser has to be able to produce sub 100 ps pulses with peak power of at least 1 W. Since these parameters are quite feasible at the current stage of diode laser science this combination of techniques can be used for single shot measurement of a short electron bunch. (3) In carrying out the above effort a simpler measurement possibility was uncovered involving the visible/nearIR pulse of incoherent radiation produced by the same bunch. This observation made possible the cross-correlation of the THz coherent and visible incoherent

  9. Detection of reactive oxygen species in isolated, perfused lungs by electron spin resonance spectroscopy

    Directory of Open Access Journals (Sweden)

    Schudt Christian

    2005-07-01

    Full Text Available Abstract Background The sources and measurement of reactive oxygen species (ROS in intact organs are largely unresolved. This may be related to methodological problems associated with the techniques currently employed for ROS detection. Electron spin resonance (ESR with spin trapping is a specific method for ROS detection, and may address some these technical problems. Methods We have established a protocol for the measurement of intravascular ROS release from isolated buffer-perfused and ventilated rabbit and mouse lungs, combining lung perfusion with the spin probe l-hydroxy-3-carboxy-2,2,5,5-tetramethylpyrrolidine (CPH and ESR spectroscopy. We then employed this technique to characterize hypoxia-dependent ROS release, with specific attention paid to NADPH oxidase-dependent superoxide formation as a possible vasoconstrictor pathway. Results While perfusing lungs with CPH over a range of inspired oxygen concentrations (1–21 %, the rate of CP• formation exhibited an oxygen-dependence, with a minimum at 2.5 % O2. Addition of superoxide dismutase (SOD to the buffer fluid illustrated that a minor proportion of this intravascular ROS leak was attributable to superoxide. Stimulation of the lungs by injection of phorbol-12-myristate-13-acetate (PMA into the pulmonary artery caused a rapid increase in CP• formation, concomitant with pulmonary vasoconstriction. Both the PMA-induced CPH oxidation and the vasoconstrictor response were largely suppressed by SOD. When the PMA challenge was performed at different oxygen concentrations, maximum superoxide liberation and pulmonary vasoconstriction occurred at 5 % O2. Using a NADPH oxidase inhibitor and NADPH-oxidase deficient mice, we illustrated that the PMA-induced superoxide release was attributable to the stimulation of NADPH oxidases. Conclusion The perfusion of isolated lungs with CPH is suitable for detection of intravascular ROS release by ESR spectroscopy. We employed this technique to

  10. Measurement of free radicals using electron paramagnetic resonance spectroscopy during open aorto-iliac arterial reconstruction.

    Science.gov (United States)

    Majewski, Wacław; Krzyminiewski, Ryszard; Stanisić, Michał; Iskra, Maria; Krasiński, Zbigniew; Nowak, Marek; Dobosz, Bernadeta

    2014-11-27

    Aortic cross-clamping during abdominal aortic aneurysm (AAA) open repair leads to development of ischemia-reperfusion injury. Electron paramagnetic resonance spectroscopy (EPR) spin-trapping is a valuable method of direct measurement of free radicals. The objective of the study was to evaluate the results of EPR as a direct method of free radical measurement and degree of inflammatory response in open operative treatment of patients with AAA and aorto-iliac occlusive disease (AIOD). The study was performed on a group of 32 patients with AAA and 25 patients with AIOD scheduled for open repair. Peripheral venous blood for EPR spectroscopy and for SOD, GPx, ox-LDL, Il-6, TNF-alfa, CRP, and HO-1 were harvested. Selected parameters were established accordingly to specified EPR and immunohistochemical methods and analyzed between groups by Mann-Whitney U test and Wilcoxon matched-pairs signed-ranks test with Bonferroni correction. Free radicals level was correlated with the time of the aortic cross-clamping after the reperfusion of he first and second leg in AAA (r=0.7; r=0.47). ox-LDL in AAA decreased 5 min after reperfusion of the first leg (32.99 U/L, range: 14.09-77.12) and 5 min after reperfusion of the second leg (26.75 U/L, range: 11.56-82.12) and 24 h after the operation (25.85 U/L, range: 14.29-49.70). HO-1 concentration increased to above the level before intervention 24 h after surgery. The activities of GPx and SOD decreased 5 min after the first-leg reperfusion in AAA. Twenty-four hours after surgery, inflammatory markers increased in AAA to CRP was 14.76 ml/l (0.23-38.55), IL-6 was 141.22 pg/ml (84.3-591.03), TNF-alfa was 6.82 pg/ml (1.76-80.01) and AIOD: CRP was 18.44 mg/l (2.56-33.14), IL-6: 184.1 pg/ml (128.46-448.03), TNF-alfa was 7.74 pg/ml (1.74-74.74). EPR spin-trapping demonstrates temporarily elevated level of free radicals in early phase of reperfusion, leading to decrease antioxidants in AAA. Elevated free radical levels decreased 24 h after

  11. Materials characterization by photoelectron spectroscopy; Caracterizacao de materiais por espectroscopia de fotoeletrons

    Energy Technology Data Exchange (ETDEWEB)

    Nascente, P.A.P., E-mail: nascente@ufscar.b [Universidade Federal de Sao Carlos (DEMa/UFSCar), SP (Brazil). Dept. de Engenharia de Materiais

    2010-07-01

    Low energy electrons are suitable for investigating surfaces due to their low mean free path in solids, which correspond to a few atomic layers (0.5 to 3.0 nm), and could be used in one of the following ways: incident electrons cause the emission of backscattered and secondary electrons and the electrons are excited by irradiated photons. The first case includes the emission of Auger electrons, while photoemission corresponds to the second case. X-ray photoelectron spectroscopy (XPS) is one of the most used surface analysis techniques since it is able to identify not only the surface constituents but also their chemical states. XPS can be employed in several areas of science and engineering, but in this report it will be presented only few examples of its use in the characterization of metallic materials, with an emphasis on thin films of noble and transition metals. (author)

  12. Photon-induced Auger effect in biological systems: a review.

    Science.gov (United States)

    Yokoya, Akinari; Ito, Takashi

    2017-08-01

    In this paper, we review interesting findings reported in the studies of the biological effects induced by inner-shell ionization with the aim of interpreting them from a mechanistic viewpoint, in particular, of the Auger effect of atoms on different biological systems. More than 70 published papers are cited on the Auger effects ranging from DNA-related elements (carbon, nitrogen, oxygen and phosphorus) to mammalian cells. Externally administrated bromine, iodine, and platinum have also been cited for the present endeavor. Those significant works all needed a highly monochromatized X-rays from brilliant synchrotron light sources. We have assembled a coherent view on the inner-shell effects of the Auger process that contrasts to the overall effects with the outer-shell ionization processes. Some of these studies have reported that the Auger effect significantly enhances biological effects as compared with irradiation at below K-ionization energy. The Auger-specific molecular degradation mode of DNA, involving extensive fragmentation of the deoxypentose moiety, has also been revealed. We conclude that the selectively localized effect on the specified atoms through inner-shell ionization followed by the Auger process should have a definite impact on the current radiation effect studies, which are largely based on non-selective outer-shell ionizations.

  13. Raman Spectroscopy of InAs Based Nanowires & Electronic Characterization of Heterostructure InAs/GaInAs Nanowires

    DEFF Research Database (Denmark)

    Tanta, Rawa

    The work presented in this thesis represents two main topics. The first one, which covers a bigger volume of the thesis, is mainly about Raman spectroscopy on individual InAs based nanowires. The second part presents electronic characterization of heterostructure InAs/GaInAs nanowires. Raman...... modes. In the last chapter of this thesis we present a study on electrical characterization of InAs/GaInAs heterostructure nanowires. First, we performed selective etching experiments in order to locate the barriers. Second, the barriers were probed electrically by performing thermally activated...... spectroscopy measurements on InAs based nanowires include several topics. Firstly, we use polarized Raman spectroscopy for determining the crystal orientation of the nanowires based on conventional Raman selection rules. We studied the effect of the high power laser irradiation on the nanowire, and its...

  14. Radiationless Raman versus Auger behavior at the $Cu L_{3}$ resonance of CuO and $Cu_{2}O$

    CERN Document Server

    Ghiringhelli, G; Ohresser, P; Brookes, N B

    2000-01-01

    We have investigated the behavior of the 2p3p3p and 2p3s3p Auger lines of CuO and Cu/sub 2/O scanning the photon energy across the Cu L/sub 3/ resonance. For both samples, when the excitation energy is below the L/sub 3/ resonance, we observe the 2p3p3p and 2p3s3p peaks at constant binding energy. This behavior is typical of nonradiative resonant Raman scattering. If the photon energy is raised above the L /sub 3/ maximum, the two samples behave in different ways. In CuO, the Auger peaks are always observed at constant binding energy, while in Cu/sub 2/O their kinetic energy first reaches a maximum at correspondence with the absorption threshold, and then stabilizes at a value slightly higher than the off-resonance Auger peaks. These differences are interpreted in terms of the different electronic structure of the Auger intermediate state at resonance. In CuO, the intermediate state corresponds to a single 2p/sub 3/2/ core hole, with the Cu 3d band completely filled. On the contrary, in Cu/sub 2/O the interme...

  15. Excitonic, vibrational, and van der Waals interactions in electron energy loss spectroscopy.

    Science.gov (United States)

    Mizoguchi, T; Miyata, T; Olovsson, W

    2017-09-01

    The pioneer, Ondrej L. Krivanek, and his collaborators have opened up many frontiers for the electron energy loss spectroscopy (EELS), and they have demonstrated new potentials of the EELS method for investigating materials. Here, inspired by those achievements, we show further potentials of EELS based on the results of theoretical calculations, that is excitonic and van der Waals (vdW) interactions, as well as vibrational information of materials. Concerning the excitonic interactions, we highlight the importance of the two-particle calculation to reproduce the low energy-loss near-edge structure (ELNES), the Na-L 2,3 edge of NaI and the Li-K edge of LiCl and LiFePO 4 . Furthermore, an unusually strong excitonic interaction at the O-K edge of perovskite oxides, SrTiO 3 and LaAlO 3 , is shown. The effect of the vdW interaction in the ELNES is also investigated, and we observe that the magnitude of the vdW effect is approximately 0.1eV in the case of the ELNES from a solid and liquid, whereas its effect is almost negligible in the case of the ELNES from the gaseous phase owing to the long inter-molecular distance. In addition to the "static" information, the influence of the "dynamic" behavior of atoms in materials to EELS is also investigated. We show that measurements of the infrared spectrum are possible by using a modern monochromator system. Furthermore, an estimation of the atomic vibration in core-loss ELNES is also presented. We show the acquisition of vibrational information using the ELNES of liquid methanol and acetic acid, solid Al 2 O 3 , and oxygen gas. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Characterization of iron, manganese, and copper synthetic hydroxyapatites by electron paramagnetic resonance spectroscopy

    Science.gov (United States)

    Sutter, B.; Wasowicz, T.; Howard, T.; Hossner, L. R.; Ming, D. W.

    2002-01-01

    The incorporation of micronutrients (e.g., Fe, Mn, Cu) into synthetic hydroxyapatite (SHA) is proposed for slow release of these nutrients to crops in NASA's Advanced Life Support (ALS) program for long-duration space missions. Separate Fe3+ (Fe-SHA), Mn2+ (Mn-SHA), and Cu2+ (Cu-SHA) containing SHA materials were synthesized by a precipitation method. Electron paramagnetic resonance (EPR) spectroscopy was used to determine the location of Fe3+, Mn2+, and Cu2+ ions in the SHA structure and to identify other Fe(3+)-, Mn(2+)-, and Cu(2+)-containing phases that formed during precipitation. The EPR parameters for Fe3+ (g=4.20 and 8.93) and for Mn2+ (g=2.01, A=9.4 mT, D=39.0 mT and E=10.5 mT) indicated that Fe3+ and Mn2+ possessed rhombic ion crystal fields within the SHA structure. The Cu2+ EPR parameters (g(z)=2.488, A(z)=5.2 mT) indicated that Cu2+ was coordinated to more than six oxygens. The rhombic environments of Fe3+ and Mn2+ along with the unique Cu2+ environment suggested that these metals substituted for the 7 or 9 coordinate Ca2+ in SHA. The EPR analyses also detected poorly crystalline metal oxyhydroxides or metal-phosphates associated with SHA. The Fe-, Mn-, and Cu-SHA materials are potential slow release sources of Fe, Mn, and Cu for ALS and terrestrial cropping systems.

  17. FTIR spectroscopy of the reaction center of Chloroflexus aurantiacus: photoreduction of the bacteriopheophytin electron acceptor.

    Science.gov (United States)

    Zabelin, Alexej A; Shkuropatova, Valentina A; Shuvalov, Vladimir A; Shkuropatov, Anatoly Ya

    2011-09-01

    Mid-infrared spectral changes associated with the photoreduction of the bacteriopheophytin electron acceptor H(A) in reaction centers (RCs) of the filamentous anoxygenic phototrophic bacterium Chloroflexus (Cfl.) aurantiacus are examined by light-induced Fourier transform infrared (FTIR) spectroscopy. The light-induced H(A)(-)/H(A) FTIR (1800-1200cm(-1)) difference spectrum of Cfl. aurantiacus RCs is compared to that of the previously well characterized purple bacterium Rhodobacter (Rba.) sphaeroides RCs. The most notable feature is that the large negative IR band at 1674cm(-1) in Rba. sphaeroides R-26, attributable to the loss of the absorption of the 13(1)-keto carbonyl of H(A) upon the radical anion H(A)(-) formation, exhibits only a very minor upshift to 1675cm(-1) in Cfl. aurantiacus. In contrast, the absorption band of the 13¹-keto C=O of H(A)(-) is strongly upshifted in the spectrum of Cfl. aurantiacus compared to that of Rba. sphaeroides (from 1588 to 1623cm(-1)). The data are discussed in terms of: (i) replacing the glutamic acid at L104 in Rba. sphaeroides R-26 RCs by a weaker hydrogen bond donor, a glutamine, at the equivalent position L143 in Cfl. aurantiacus RCs; (ii) a strengthening of the hydrogen-bonding interaction of the 13¹-keto C=O of H(A) with Glu L104 and Gln L143 upon H(A)(-) formation and (iii) a possible influence of the protein dielectric environment on the 13¹-keto C=O stretching frequency of neutral H(A). A conformational heterogeneity of the 13³-ester C=O group of H(A) is detected for Cfl. aurantiacus RCs similar to what has been previously described for purple bacterial RCs. 2011 Elsevier B.V. All rights reserved.

  18. Vibrational Surface Electron-Energy-Loss Spectroscopy Probes Confined Surface-Phonon Modes

    Directory of Open Access Journals (Sweden)

    Hugo Lourenço-Martins

    2017-12-01

    Full Text Available Recently, two reports [Krivanek et al. Nature (London 514, 209 (2014NATUAS0028-083610.1038/nature13870, Lagos et al. Nature (London 543, 529 (2017NATUAS0028-083610.1038/nature21699] have demonstrated the amazing possibility to probe vibrational excitations from nanoparticles with a spatial resolution much smaller than the corresponding free-space phonon wavelength using electron-energy-loss spectroscopy (EELS. While Lagos et al. evidenced a strong spatial and spectral modulation of the EELS signal over a nanoparticle, Krivanek et al. did not. Here, we show that discrepancies among different EELS experiments as well as their relation to optical near- and far-field optical experiments [Dai et al. Science 343, 1125 (2014SCIEAS0036-807510.1126/science.1246833] can be understood by introducing the concept of confined bright and dark surface phonon modes, whose density of states is probed by EELS. Such a concise formalism is the vibrational counterpart of the broadly used formalism for localized surface plasmons [Ouyang and Isaacson Philos. Mag. B 60, 481 (1989PMABDJ1364-281210.1080/13642818908205921, García de Abajo and Aizpurua Phys. Rev. B 56, 15873 (1997PRBMDO0163-182910.1103/PhysRevB.56.15873, García de Abajo and Kociak Phys. Rev. Lett. 100, 106804 (2008PRLTAO0031-900710.1103/PhysRevLett.100.106804, Boudarham and Kociak Phys. Rev. B 85, 245447 (2012PRBMDO1098-012110.1103/PhysRevB.85.245447]; it makes it straightforward to predict or interpret phenomena already known for localized surface plasmons such as environment-related energy shifts or the possibility of 3D mapping of the related surface charge densities [Collins et al. ACS Photonics 2, 1628 (2015APCHD52330-402210.1021/acsphotonics.5b00421].

  19. Study of nanostructural organization of ionic liquids by electron paramagnetic resonance spectroscopy.

    Science.gov (United States)

    Merunka, Dalibor; Peric, Mirna; Peric, Miroslav

    2015-02-19

    The X-band electron paramagnetic resonance spectroscopy (EPR) of a stable, spherical nitroxide spin probe, perdeuterated 2,2,6,6-tetramethyl-4-oxopiperidine-1-oxyl (pDTO) has been used to study the nanostructural organization of a series of 1-alkyl-3-methylimidazolium tetrafluoroborate ionic liquids (ILs) with alkyl chain lengths from two to eight carbons. By employing nonlinear least-squares fitting of the EPR spectra, we have obtained values of the rotational correlation time and hyperfine coupling splitting of pDTO to high precision. The rotational correlation time of pDTO in ILs and squalane, a viscous alkane, can be fit very well to a power law functionality with a singular temperature, which often describes a number of physical quantities measured in supercooled liquids. The viscosity of the ILs and squalane, taken from the literature, can also be fit to the same power law expression, which means that the rotational correlation times and the ionic liquid viscosities have similar functional dependence on temperature. The apparent activation energy of both the rotational correlation time of pDTO and the viscous flow of ILs and squalane increases with decreasing temperature; in other words, they exhibit strong non-Arrhenius behavior. The rotational correlation time of pDTO as a function of η/T, where η is the shear viscosity and T is the temperature, is well described by the Stokes-Einstein-Debye (SED) law, while the hydrodynamic probe radii are solvent dependent and are smaller than the geometric radius of the probe. The temperature dependence of hyperfine coupling splitting is the same in all four ionic liquids. The value of the hyperfine coupling splitting starts decreasing with increasing alkyl chain length in the ionic liquids in which the number of carbons in the alkyl chain is greater than four. This decrease together with the decrease in the hydrodynamic radius of the probe indicates a possible existence of nonpolar nanodomains.

  20. FTIR spectroscopy of the reaction center of Chloroflexus aurantiacus: photooxidation of the primary electron donor.

    Science.gov (United States)

    Zabelin, A A; Shkuropatova, V A; Shuvalov, V A; Shkuropatov, A Ya

    2012-02-01

    Photochemical oxidation of the primary electron donor P in reaction centers (RCs) of the filamentous anoxygenic phototrophic bacterium Chloroflexus (C.) aurantiacus was examined by light-induced Fourier transform infrared (FTIR) difference spectroscopy at 95 K in the spectral range of 4000-1200 cm(-1). The light-induced P(+)Q(A)(-)/PQ(A) IR spectrum of C. aurantiacus RCs is compared to the well-characterized FTIR difference spectrum of P photooxidation in the purple bacterium Rhodobacter (R.) sphaeroides R-26 RCs. The presence in the P(+)Q(A)(-)/PQ(A) FTIR spectrum of C. aurantiacus RCs of specific low-energy electronic transitions at ~2650 and ~2200 cm(-1), as well as of associated vibrational (phase-phonon) bands at 1567, 1481, and 1294-1285 cm(-1), indicates that the radical cation P(+) in these RCs has dimeric structure, with the positive charge distributed between the two coupled bacteriochlorophyll a molecules. The intensity of the P(+) absorbance band at ~1250 nm (upon chemical oxidation of P at room temperature) in C. aurantiacus RCs is approximately 1.5 times lower than that in R. sphaeroides R-26 RCs. This fact, together with the decreased intensity of the absorbance band at ~2650 cm(-1), is interpreted in terms of the weaker coupling of bacteriochlorophylls in the P(+) dimer in C. aurantiacus compared to R. sphaeroides R-26. In accordance with the previous (pre)resonance Raman data, FTIR measurements in the carbonyl stretching region show that in C. aurantiacus RCs (i) the 13(1)-keto C=O groups of P(A) and P(B-) molecules constituting the P dimer are not involved in hydrogen bonding in either neutral or photooxidized state of P and (ii) the 3(1)-acetyl C=O group of P(B) forms a hydrogen bond (probably with tyrosine M187) absorbing at 1635 cm(-1). Differential signals at 1757(+)/1749(-) and 1741(+)/1733(-) cm(-1) in the FTIR spectrum of C. aurantiacus RCs are attributed to the 13(3)-ester C=O groups of P in different environments.

  1. Probing environment fluctuations by two-dimensional electronic spectroscopy of molecular systems at temperatures below 5 K

    Energy Technology Data Exchange (ETDEWEB)

    Rancova, Olga; Abramavicius, Darius [Department of Theoretical Physics, Vilnius University, Sauletekio al 9-III, 10222 Vilnius (Lithuania); Jankowiak, Ryszard [Department of Chemistry and Department of Physics, Kansas State University, 213 CBC Building Manhattan, Kansas 66506-0401 (United States)

    2015-06-07

    Two-dimensional (2D) electronic spectroscopy at cryogenic and room temperatures reveals excitation energy relaxation and transport, as well as vibrational dynamics, in molecular systems. These phenomena are related to the spectral densities of nuclear degrees of freedom, which are directly accessible by means of hole burning and fluorescence line narrowing approaches at low temperatures (few K). The 2D spectroscopy, in principle, should reveal more details about the fluctuating environment than the 1D approaches due to peak extension into extra dimension. By studying the spectral line shapes of a dimeric aggregate at low temperature, we demonstrate that 2D spectra have the potential to reveal the fluctuation spectral densities for different electronic states, the interstate correlation of static disorder and, finally, the time scales of spectral diffusion with high resolution.

  2. Insights into the Structural Changes Occurring upon Photoconversion in the Orange Carotenoid Protein from Broadband Two-Dimensional Electronic Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    De Re, Eleonora; Schlau-Cohen, Gabriela S.; Leverenz, Ryan L.; Huxter, Vanessa M.; Oliver, Thomas A. A.; Mathies, Richard A.; Fleming, Graham R.

    2014-05-22

    Carotenoids play an essential role in photoprotection, interacting with other pigments to safely dissipate excess absorbed energy as heat. In cyanobacteria, the short time scale photoprotective mechanisms involve the photoactive orange carotenoid protein (OCP), which binds a single carbonyl carotenoid. Blue-green light induces the photoswitching of OCP from its ground state form (OCPO) to a metastable photoproduct (OCPR). OCPR can bind to the phycobilisome antenna and induce fluorescence quenching. The photoswitching is accompanied by structural and functional changes at the level of the protein and of the bound carotenoid. In this study, we use broadband two-dimensional electronic spectroscopy to look at the differences in excited state dynamics of the carotenoid in the two forms of OCP. Our results provide insight into the origin of the pronounced vibrational lineshape and oscillatory dynamics observed in linear absorption and 2D electronic spectroscopy of OCPO and the large inhomogeneous broadening in OCPR, with consequences for the chemical function of the two forms.

  3. Characterization of structural alteration in diamond turned silicon crystal by means of micro raman spectroscopy and transmission electron microscopy

    Directory of Open Access Journals (Sweden)

    Renato Goulart Jasinevicius

    2005-09-01

    Full Text Available In this work, (100 oriented monocrystalline silicon samples were single point diamond turned under conditions that led to a ductile and brittle regime. Raman spectroscopy results showed that the ductile regime diamond turning of silicon surfaces induced amorphization and, on the contrary, in the brittle mode machining condition this amorphous layer does not exist. Ductile machined surface was found to be a mixture of crystalline and amorphous phases probed by (macro-Raman spectroscopy. Transmission Electron Microscopy (TEM analyses were then carried out in order to characterize the structural alteration in the machined surface and chips. The electron diffraction pattern of the machined surface detected a crystalline phase along with the amorphous silicon confirming the former results. The mechanism of material removal is widely discussed based upon the results presented here.

  4. Correlated single-crystal electronic absorption spectroscopy and X-ray crystallography at NSLS beamline X26-C.

    Science.gov (United States)

    Orville, Allen M; Buono, Richard; Cowan, Matt; Héroux, Annie; Shea-McCarthy, Grace; Schneider, Dieter K; Skinner, John M; Skinner, Michael J; Stoner-Ma, Deborah; Sweet, Robert M

    2011-05-01

    The research philosophy and new capabilities installed at NSLS beamline X26-C to support electronic absorption and Raman spectroscopies coupled with X-ray diffraction are reviewed. This beamline is dedicated full time to multidisciplinary studies with goals that include revealing the relationship between the electronic and atomic structures in macromolecules. The beamline instrumentation has been fully integrated such that optical absorption spectra and X-ray diffraction images are interlaced. Therefore, optical changes induced by X-ray exposure can be correlated with X-ray diffraction data collection. The installation of Raman spectroscopy into the beamline is also briefly reviewed. Data are now routinely generated almost simultaneously from three complementary types of experiments from the same sample. The beamline is available now to the NSLS general user population.

  5. The Pierre Auger Observatory status and the AugerPrime upgrade program

    Directory of Open Access Journals (Sweden)

    Martello Daniele

    2017-01-01

    Full Text Available The nature and the origin of ultra-high energy cosmic rays (UHECRs, above 1017 eV, are still unknown. The Pierre Auger Observatory with its huge exposure provides us with a large set of high quality data. The analysis of these data has led to major breakthroughs in the last decade, but a coherent interpretation is still missing. To answer the open questions the Observatory has started a major upgrade, with an emphasis on improved mass composition determination using the surface detectors. The latest results and the planned detector upgrade will be presented. The expected performance and the improved physics sensitivity of the Observatory will be discussed.

  6. FOREWORD: VI Workshop in Electron Volt Neutron Spectroscopy: Frontiers and Horizons

    Science.gov (United States)

    Seel, A. G.; Senesi, R.; Fernandez-Alonso, F.

    2014-12-01

    January 2014 saw the congregation in Abingdon (UK) of scientists from across the world, to discuss the current state and future of spectroscopy using epithermal neutrons. This meeting was the sixth in a series of workshops held in collaboration between the Science and Technology Facilities Council (UK) and the Consiglio Nazionale delle Ricerche (Italy), aimed at bringing together researchers with an interest in the use of electron-volt neutrons in spectroscopic studies [1]. This technique is termed Deep Inelastic Neutron Scattering (DINS), and also Neutron Compton Scattering (NCS) in reference to the analogy with Compton scattering of X-rays from electrons. In particular, this meeting centred jointly around experimentalists and theoreticians, formulating animated discussions as to the current overview of DINS and future horizons facing the field. The use of electron Volt neutrons for spectroscopic measurements dates back to the advent of proton-driven spallation neutron sources in the 1970s and 1980s. Following an initial scientific meeting in Los Alamos (USA) [2], the first two meetings in this series were held in Abingdon (UK) in 1995 and 1998, with subsequent meetings held in Santa Fe (USA) in 2005 [3], Oak Ridge National Laboratory (USA) in 2006 [4], and Rome, Italy; in 2010 [5]. The flagship instrument serving a continual user-programme for DINS measurements, and the main focus of this meeting, has been the VESUVIO spectrometer at ISIS [6, 7]. Subsequent instruments like SEQUOIA in the USA [8, 9] and a newer spectrometer in the Bariloche LINAC in Argentina [10, 11] have also been commissioned and began serving a growing user community. The availability of DINS measurements has extended the range of possible spectroscopic techniques that utilise neutrons into the kinematic region of high energy and momentum transfers, shown schematically in Figure 1. Spectroscopic instrument suites such as that of ISIS are thus able to probe processes on timescales across nine

  7. Formation and characterization of varied size germanium nanocrystals by electron microscopy, Raman spectroscopy, and photoluminescence

    DEFF Research Database (Denmark)

    Ou, Haiyan; Ou, Yiyu; Liu, Chuan

    2011-01-01

    and crystallization. The samples of different size Ge nanocrystals embedded in the SiO2 matrix were characterized by Raman spectroscopy and photoluminescence. Interplayed size and strain effect of Ge nanocystals was demonstrated by Raman spectroscopy after excluding the thermal effect with proper excitation laser...

  8. Investigation of Antioxidant Activity of Pomegranate Juices by Means of Electron Paramagnetic Resonance and UV-Vis Spectroscopy.

    Science.gov (United States)

    Kozik, Violetta; Jarzembek, Krystyna; Jędrzejowska, Agnieszka; Bąk, Andrzej; Polak, Justyna; Bartoszek, Mariola; Pytlakowska, Katarzyna

    2015-01-01

    Pomegranate fruit (Punica granatum L.) is a source of numerous phenolic compounds, and it contains flavonoids such as anthocyanins, anthocyanidins, cyanidins, catechins and other complexes of flavonoids, ellagitannins, and hydrolyzed tannins. Pomegranate juice shows antioxidant, antiproliferative, and anti-atherosclerotic properties. The antioxidant capacity (TEAC) of the pomegranate juices was measured using electron paramagnetic resonance (EPR) spectroscopy and 1,1-diphenyl-2-picrylhydrazyl (DPPH•) as a source of free radicals, and the total phenolic (TP) content was measured using UV-Vis spectroscopy. All the examined pomegranate juices exhibited relatively high antioxidant properties. The TEAC values determined by means of EPR spectroscopy using Trolox (TE) as a free radical scavenger were in the range of 463.12 to 1911.91 μmol TE/100 mL juice. The TP content measured by the Folin-Ciocalteu method, using gallic acid (GA) as a free radical scavenger, widely varied in the investigated pomegranate juice samples and ranged from 1673.62 to 5263.87 mg GA/1 L juice. The strongest antioxidant properties were observed with the fresh pomegranate juices obtained from the fruits originating from Israel, Lebanon, and Azerbaijan. Correlation analysis of numerical data obtained by means of EPR spectroscopy (TEAC) and UV-Vis spectroscopy (TP) gave correlation coefficient (r)=0.90 and determination coefficient (r2)=0.81 (P<0.05).

  9. Determination of the antiproton-to-electron mass ratio by precision laser spectroscopy of $\\overline{p}He^{+}$

    CERN Document Server

    Hori, M; Eades, John; Gomikawa, K; Hayano, R S; Ono, N; Pirkl, Werner; Widmann, E; Torii, H A; Juhász, B; Barna, D; Horváth, D

    2006-01-01

    A femtosecond optical frequency comb and continuous-wave pulse- amplified laser were used to measure 12 transition frequencies of antiprotonic helium to fractional precisions of (9-16) 10/sup -9lifetimes hitherto unaccessible to our precision laser spectroscopy method. Comparisons with three-body QED calculations yielded an antiproton-to-electron mass ratio of M/sub pmacron//m/sub e/=1836.152 674(5).

  10. Fourier transform two-dimensional electronic-vibrational spectroscopy using an octave-spanning mid-IR probe.

    Science.gov (United States)

    Gaynor, James D; Courtney, Trevor L; Balasubramanian, Madhumitha; Khalil, Munira

    2016-06-15

    The development of coherent Fourier transform two-dimensional electronic-vibrational (2D EV) spectroscopy with acousto-optic pulse-shaper-generated near-UV pump pulses and an octave-spanning broadband mid-IR probe pulse is detailed. A 2D EV spectrum of a silicon wafer demonstrates the full experimental capability of this experiment, and a 2D EV spectrum of dissolved hexacyanoferrate establishes the viability of our 2D EV experiment for studying condensed phase molecular ensembles.

  11. Determination of Chromium Valence Over the Range Cr(0)-Cr(VI) by Electron Energy Loss Spectroscopy

    Science.gov (United States)

    2006-01-01

    be of Cr (VI): Cr (V) [14,40-45] and Cr (IV) [46]. To fully altered by microbes [11-13], green algae [14], higher plants understand the geochemistry of Cr ... Cr (III) by bacteria [42,44,45] and Further, nearly all mineralized Cr in the terrestrial crust is green algae [14], reacts with diphenylcarbazide to...Determination of chromium valence over the range Cr (O)- Cr (VI) by electron energy loss spectroscopy Tyrone L. Daultona , Brenda J. Littleb ’Marine

  12. Ultralong range ICD in the He dimer, resonant Auger - ICD cascade processes

    Energy Technology Data Exchange (ETDEWEB)

    Jahnke, Till [IKF, Goethe Universitaet, Max-von-Laue-Str.1, 60438 Frankfurt am Main (Germany)

    2013-07-01

    Interatomic (or intermolecular) Coulombic Decay (ICD) has become an extensively studied atomic decay process during the last 10 years. The talk shows examples of different systems in which ICD has been examined. In particular helium molecules (so called helium dimers) are presented in which ICD occurs over longest internuclear distances. In ICD electrons of low energy are created as a typical decay product. Such electrons are known to effectively cause DNA double strand breakups suggesting ICD as a possible origin for radiation damage of living tissue. The group of L. Cederbaum recently suggested that ICD can be triggered efficiently and site-selectively by resonant excitation of molecules. They realized that this provides a unique tool to create low energy electrons at a specific site inside a biological system for example in order to damage malignant cells that are tagged using specific marker molecules. Here we show experimentally that resonant Auger induced ICD can indeed be observed in model systems of small nitrogen and carbon monoxide clusters and - as expected - produces low energy electrons. Furthermore our simple model systems are able to prove the efficiency of ICD: it occurs before the individual molecule is able to undergo dissociation, i.e on a timescale <10 fs. Our findings therefore strongly support the idea of resonant Auger-ICD being a promising process to induce radiation damage at a specific site inside a high-Z-tagged cell.

  13. Femtosecond X-ray magnetic circular dichroism absorption spectroscopy at an X-ray free electron laser

    Science.gov (United States)

    Higley, Daniel J.; Hirsch, Konstantin; Dakovski, Georgi L.; Jal, Emmanuelle; Yuan, Edwin; Liu, Tianmin; Lutman, Alberto A.; MacArthur, James P.; Arenholz, Elke; Chen, Zhao; Coslovich, Giacomo; Denes, Peter; Granitzka, Patrick W.; Hart, Philip; Hoffmann, Matthias C.; Joseph, John; Le Guyader, Loïc; Mitra, Ankush; Moeller, Stefan; Ohldag, Hendrik; Seaberg, Matthew; Shafer, Padraic; Stöhr, Joachim; Tsukamoto, Arata; Nuhn, Heinz-Dieter; Reid, Alex H.; Dürr, Hermann A.; Schlotter, William F.

    2016-03-01

    X-ray magnetic circular dichroism spectroscopy using an X-ray free electron laser is demonstrated with spectra over the Fe L3,2-edges. The high brightness of the X-ray free electron laser combined with high accuracy detection of incident and transmitted X-rays enables ultrafast X-ray magnetic circular dichroism studies of unprecedented sensitivity. This new capability is applied to a study of all-optical magnetic switching dynamics of Fe and Gd magnetic sublattices in a GdFeCo thin film above its magnetization compensation temperature.

  14. Femtosecond X-ray magnetic circular dichroism absorption spectroscopy at an X-ray free electron laser.

    Science.gov (United States)

    Higley, Daniel J; Hirsch, Konstantin; Dakovski, Georgi L; Jal, Emmanuelle; Yuan, Edwin; Liu, Tianmin; Lutman, Alberto A; MacArthur, James P; Arenholz, Elke; Chen, Zhao; Coslovich, Giacomo; Denes, Peter; Granitzka, Patrick W; Hart, Philip; Hoffmann, Matthias C; Joseph, John; Le Guyader, Loïc; Mitra, Ankush; Moeller, Stefan; Ohldag, Hendrik; Seaberg, Matthew; Shafer, Padraic; Stöhr, Joachim; Tsukamoto, Arata; Nuhn, Heinz-Dieter; Reid, Alex H; Dürr, Hermann A; Schlotter, William F

    2016-03-01

    X-ray magnetic circular dichroism spectroscopy using an X-ray free electron laser is demonstrated with spectra over the Fe L(3,2)-edges. The high brightness of the X-ray free electron laser combined with high accuracy detection of incident and transmitted X-rays enables ultrafast X-ray magnetic circular dichroism studies of unprecedented sensitivity. This new capability is applied to a study of all-optical magnetic switching dynamics of Fe and Gd magnetic sublattices in a GdFeCo thin film above its magnetization compensation temperature.

  15. Femtosecond X-ray magnetic circular dichroism absorption spectroscopy at an X-ray free electron laser

    Energy Technology Data Exchange (ETDEWEB)

    Higley, Daniel J., E-mail: dhigley@stanford.edu; Yuan, Edwin [SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025 (United States); Department of Applied Physics, Stanford University, Stanford, California 94305 (United States); Hirsch, Konstantin; Dakovski, Georgi L.; Jal, Emmanuelle; Lutman, Alberto A.; Coslovich, Giacomo; Hart, Philip; Hoffmann, Matthias C.; Mitra, Ankush; Moeller, Stefan; Ohldag, Hendrik; Seaberg, Matthew; Stöhr, Joachim; Nuhn, Heinz-Dieter; Reid, Alex H.; Dürr, Hermann A.; Schlotter, William F. [SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025 (United States); Liu, Tianmin; MacArthur, James P. [SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025 (United States); Department of Physics, Stanford University, Stanford, California 94305 (United States); and others

    2016-03-15

    X-ray magnetic circular dichroism spectroscopy using an X-ray free electron laser is demonstrated with spectra over the Fe L{sub 3,2}-edges. The high brightness of the X-ray free electron laser combined with high accuracy detection of incident and transmitted X-rays enables ultrafast X-ray magnetic circular dichroism studies of unprecedented sensitivity. This new capability is applied to a study of all-optical magnetic switching dynamics of Fe and Gd magnetic sublattices in a GdFeCo thin film above its magnetization compensation temperature.

  16. The substrate effect in electron energy-loss spectroscopy of localized surface plasmons in gold and silver nanoparticles

    DEFF Research Database (Denmark)

    Kadkhodazadeh, Shima; Christensen, Thomas; Beleggia, Marco

    2017-01-01

    , as in optical measurements, the substrate material can modify the acquired signal. Here, we have investigated how the EELS signal recorded from supported silver and gold spheroidal nanoparticles at different electron beam impact parameter positions is affected by the choice of a dielectric substrate material......Electron energy-loss spectroscopy (EELS) has become increasingly popular for detailed characterization of plasmonic nanostructures, owing to the unparalleled spatial resolution of this technique. The typical setup in EELS requires nanoparticles to be supported on thin substrates. However...

  17. Plasmon Modulation Spectroscopy of Noble Metals to Reveal the Distribution of the Fermi Surface Electrons in the Conduction Band

    Directory of Open Access Journals (Sweden)

    Kentaro Takagi

    2017-12-01

    Full Text Available To directly access the dynamics of electron distribution near the Fermi-surface after plasmon excitation, pump-probe spectroscopy was performed by pumping plasmons on noble-metal films and probing the interband transition. Spectral change in the interband transitions is sensitive to the electron distribution near the Fermi-surface, because it involves the d valence-band to the conduction band transitions and should reflect the k-space distribution dynamics of electrons. For the continuous-wave pump and probe experiment, the plasmon modulation spectra are found to differ from both the current modulation and temperature difference spectra, possibly reflecting signatures of the plasmon wave function. For the femtosecond-pulse pump and probe experiment, the transient spectra agree well with the known spectra upon the excitation of the respective electrons resulting from plasmon relaxation, probably because the lifetime of plasmons is shorter than the pulse duration.

  18. Probing the electron beam induced reduction of graphite oxide by in situ X-ray photoelectron spectroscopy/mass spectrometer

    Science.gov (United States)

    Zhu, Chunhua; Hao, Xiaofei; Liu, Yu; Wu, Yeping; Wang, Jianhua

    2018-01-01

    The graphite oxide (GO) was reduced successfully by electron-beam irradiation without solution chemistry and high temperature, where the chemical structural changes and gaseous species released during the exposure was monitored directly by X-ray photoelectron spectroscopy/mass spectrometer. The degree of reduction of GO can be tuned effectively by way of electron beam intensity and irradiation time, resulting a high C/O ratio of 5.27. The evolution of C 1s spectra with irradiation time was also investigated. The CO, CO2, H2 molecules and several organic species were detected during the irradiation, confirmed that the electron beam induced the photoreduction of GO. The combined chemical structure evolution and gas species analysis make the XPS-MS highly desirable as a powerful in situ analytical instrument for tracking the reaction process. The electron-beam-induced reduction described in detail here provides potential way to fabricate graphene device from GO in one step.

  19. Firmware, detector performance and first data of the AMIGA muon counters for the Pierre Auger Observatory

    Energy Technology Data Exchange (ETDEWEB)

    Froehlich, Uwe

    2013-10-30

    With the Pierre Auger Observatory, being the largest air shower detector setup in the world, ultra-high-energy cosmic rays are studied with full trigger efficiency above E=3 x 10{sup 18} eV. In order to achieve a more detailed understanding of cosmic ray physics at lower energies down to E∼10{sup 17} eV, e.g. the transition from galactic to extragalactic sources and a possible change in the composition of the primary cosmic rays, the observatory is currently upgraded by the AMIGA enhancement (Auger Muons and Infill for the Ground Array). The muon counters of AMIGA, buried underground, will allow for dedicated measurements of the number of muons in air showers, thus increasing the precision in determining the type of the primary particle. Until middle of 2012, eight prototype muon counters of the AMIGA enhancement were installed at the experimental site of the Pierre Auger Observatory at Malargue, Argentina, forming one detector hexagon referred to as the pre-unitary cell (PUC). Each muon counter comprises a highly modular electronics readout system. Following the production of these systems, tests of single components as well as of the full readout electronics were carried out. In the framework of this thesis dedicated firmware, allowing for the commissioning and first data taking with the PUC, has been developed and tested. Among other features, this firmware includes a self-trigger of the muon counters as well as algorithms for the synchronization of the muon detector (MD) with the existing surface detector (SD) array. The functionality and performance of the electronics readout system with regard to this firmware has been investigated. In addition, first analyses of combined MD and SD data have been performed.

  20. Calculations of Auger-cascade-induced reactions with DNA in aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Hamm, R.N.; Wright, H.A.; Turner, J.E. (Oak Ridge National Lab., TN (USA)); Howell, R.W.; Rao, D.V. (University of Medicine and Dentistry of New Jersey, Newark, NJ (USA)); Sastry, K.S.R. (Massachusetts Univ., Amherst, MA (USA))

    1989-01-01

    The biological effects of radionuclides incorporated into mammalian cells are of considerable interest for radiation biology and radiation protection. Simulation of the nuclear and atomic events associated with the decay of several Auger-electron-emitting radionuclides was accomplished using Monte Carlo calculational techniques. Calculations of the energies of Auger electrons produced from a number of decays have been performed for the radionuclides Pt-195m, Pt-193m, I-125, In-111, and Fe-55. The Monte Carlo radiation transport code OREC (8, 11-13) has been used to transport the electrons produced during the Auger cascades through liquid water surrounding the decay site and to calculate the physical and chemical interactions produced. In order to estimate the interactions that might be produced with a DNA molecule, a very simple model has been assumed. A segment of double-stranded DNA is represented as a right circular cylinder of radius 1 nm with sugar'' and base'' reactive sites alternating along two helical strands on the surface. For the purposes of this paper two types of interactions with the DNA are considered. During the charged-particle transport the DNA cylinder is treated as though it were water, and if an inelastic energy loss event occurs within the cylinder it is considered to represent a direct'' physical event. An indirect'' chemical event is considered to result when a reactive chemical species interacts with a sugar'' or base'' site on the DNA. Although no attempt is made to identify the consequences of these direct or indirect events, it is interesting to compare the relative numbers of such events for various types of radiation. 13 refs., 4 figs.

  1. Electron Paramagnetic Resonance Spectroscopy and Hall Effect Studies of the Effects of Low Energy Electron Irradiation on Gallium Nitride

    National Research Council Canada - National Science Library

    Greene, Kevin

    2003-01-01

    .... Samples produced via molecular beam epitaxy and hydride vapor phase epitaxy, both silicon doped and nominally undoped, were subjected to Van de Graff generator produced monoenergtic electron beams...

  2. Xenon N4,500 Auger spectrum - a useful calibration source

    Energy Technology Data Exchange (ETDEWEB)

    Carroll, T.X.; Bozek, J.D.; Kukk, E.; Myrseth, V.; Saethre, L.J.; Thomas, T.D.; Wiesner, Karoline

    2002-02-06

    In the xenon N4,5OO Auger spectrum there are 19 prominent lines ranging from 8 to 36 eV that provide a convenient set of standards for calibrating electron spectrometers. Combining optical data with recent measurements of this spectrum gives energies for these lines that are absolutely accurate to 11 meV. For most lines the relative accuracy is better than 1 meV; for a few it is about 3 meV. The spin-orbit splitting of the xenon 4d lines is measured to be 1979.0 +- 0.5meV.

  3. Interference through the resonant Auger process via multiple core-excited states

    Science.gov (United States)

    Chatterjee, Souvik; Nakajima, Takashi

    2017-12-01

    We theoretically investigate the resonant Auger process via multiple core-excited states. The presence of multiple core-excited states sets off interference into the common final continuum, and we show that the degree of interference depends on the various parameters such as the intensity of the employed x-ray pulse and the lifetimes of the core-excited states. For the specific examples we employ the double (1 s-13 p and 1 s-14 p ) core-excited states of Ne atom and numerically solve the time-dependent Schrödinger equation to demonstrate that the energy-resolved electron spectra clearly exhibit the signature of interference.

  4. A combined photoelectron spectroscopy and relativistic ab initio studies of the electronic structures of UFO and UFO(-).

    Science.gov (United States)

    Roy, Soumendra K; Jian, Tian; Lopez, Gary V; Li, Wei-Li; Su, Jing; Bross, David H; Peterson, Kirk A; Wang, Lai-Sheng; Li, Jun

    2016-02-28

    The observation of the gaseous UFO(-) anion is reported, which is investigated using photoelectron spectroscopy and relativisitic ab initio calculations. Two strong photoelectron bands are observed at low binding energies due to electron detachment from the U-7sσ orbital. Numerous weak detachment bands are also observed due to the strongly correlated U-5f electrons. The electron affinity of UFO is measured to be 1.27(3) eV. High-level relativistic quantum chemical calculations have been carried out on the ground state and many low-lying excited states of UFO to help interpret the photoelectron spectra and understand the electronic structure of UFO. The ground state of UFO(-) is linear with an O-U-F structure and a (3)H4 spectral term derived from a U 7sσ(2)5fφ(1)5fδ(1) electron configuration, whereas the ground state of neutral UFO has a (4)H(7/2) spectral term with a U 7sσ(1)5fφ(1)5fδ(1) electron configuration. Strong electron correlation effects are found in both the anionic and neutral electronic configurations. In the UFO neutral, a high density of electronic states with strong configuration mixing is observed in most of the scalar relativistic and spin-orbit coupled states. The strong electron correlation, state mixing, and spin-orbit coupling of the electronic states make the excited states of UFO very challenging for accurate quantum chemical calculations.

  5. Structural, chemical and electronic properties of the Co2MnSi(001)/MgO interface

    OpenAIRE

    Fetzer, Roman; Wüstenberg, Jan-Peter; Taira, Tomoyuki; Uemura, Tetsuya; Yamamoto, Masafumi; Aeschlimann, Martin; Cinchetti, Mirko

    2012-01-01

    The performance of advanced magnetic tunnel junctions build of ferromagnetic (FM) electrodes and MgO as insulating barrier depends decisively on the properties of the FM/insulator interface. Here, we investigate interface formation between the half-metallic compound Co2MnSi (CMS) and MgO by means of Auger electron spectroscopy, low energy electron diffraction and low energy photoemission. The studies are performed for different annealing temperatures TA and MgO layer coverages (4, 6, 10, 20 a...

  6. Electron energy loss spectroscopy for quantitative analysis of the local atomic structure of superthin oxide films on the surface of 3d-metals

    Energy Technology Data Exchange (ETDEWEB)

    Guy, D., E-mail: ftiran@mail.r [Physical-Technical Institute, UB RAS, Kirov St., Bld.132, 426000 Izhevsk (Russian Federation); Bakieva, O. [Physical-Technical Institute, UB RAS, Kirov St., Bld.132, 426000 Izhevsk (Russian Federation); Grebennikov, V. [Institute of Metal Physics, UB RAS, GSP-170, S. Kovalevskaya St., Bld. 18, 620219 Ekaterinburg (Russian Federation); Surnin, D. [Physical-Technical Institute, UB RAS, Kirov St., Bld.132, 426000 Izhevsk (Russian Federation); Ruts, Y. [Physical-Technical Institute, UB RAS, Kirov St., Bld.132, 426000 Izhevsk (Russian Federation); Institute of Metal Physics, UB RAS, GSP-170, S. Kovalevskaya St., Bld. 18, 620219 Ekaterinburg (Russian Federation)

    2010-12-15

    In this paper we present a theoretical description of the extended energy loss fine structure (EELFS) formation, and derive simple analytical formulas for the EELFS spectra calculation. Methods of calculating the amplitude and intensity of electron transitions of different multipolarity on excitation of an atomic core level by an electron impact are proposed, and the corresponding test calculations are carried out. The M{sub 2,3} EELFS spectra of pure 3d-metals (Fe, Ni, Cu) and stoichiometric oxide films (Fe{sub 2}O{sub 3}, NiO and CuO), as well as the K EELFS spectra of oxygen, obtained with a JEOL JAMP-10 Scanning Auger microprobe are presented. A technique of extracting the normalized oscillating parts from experimental EELFS data, based on the use of the calculated electron transition intensities is suggested. The atomic pair correlation functions of the investigated objects are obtained from the experimental EELFS data with allowance for multipolarity of the processes of excitation of the atomic core level by electron impact. The experimental results agree well with the known crystallographic data (partial interatomic distances, coordination numbers and Debye-Waller factors).

  7. Probing the electronic environment of binary and ternary ionic liquid mixtures by X-ray photoelectron spectroscopy

    Science.gov (United States)

    Men, Shuang; Licence, Peter

    2017-10-01

    X-ray photoelectron spectroscopy is used to probe the electronic environment of cations and anions for three binary and one ternary chlorostannate ionic liquid mixtures. The impact of the weighting of Cl- on the electronic environment of the cation-based nitrogen atom is revealed in detail. With the increasing of the concentration of Cl-, the N 1s binding energy is decreased. The electronic environment of the anion-based component is also compared based upon Sn 3d5/2 and Cl 2p3/2 binding energies. It is found that with the increasing of the weighting of Cl-, binding energies of Sn 3d5/2 and Cl 2p3/2 both decrease.

  8. X-ray absorption spectroscopy using a self-seeded soft X-ray free-electron laser.

    Science.gov (United States)

    Kroll, Thomas; Kern, Jan; Kubin, Markus; Ratner, Daniel; Gul, Sheraz; Fuller, Franklin D; Löchel, Heike; Krzywinski, Jacek; Lutman, Alberto; Ding, Yuantao; Dakovski, Georgi L; Moeller, Stefan; Turner, Joshua J; Alonso-Mori, Roberto; Nordlund, Dennis L; Rehanek, Jens; Weniger, Christian; Firsov, Alexander; Brzhezinskaya, Maria; Chatterjee, Ruchira; Lassalle-Kaiser, Benedikt; Sierra, Raymond G; Laksmono, Hartawan; Hill, Ethan; Borovik, Andrew; Erko, Alexei; Föhlisch, Alexander; Mitzner, Rolf; Yachandra, Vittal K; Yano, Junko; Wernet, Philippe; Bergmann, Uwe

    2016-10-03

    X-ray free electron lasers (XFELs) enable unprecedented new ways to study the electronic structure and dynamics of transition metal systems. L-edge absorption spectroscopy is a powerful technique for such studies and the feasibility of this method at XFELs for solutions and solids has been demonstrated. However, the required x-ray bandwidth is an order of magnitude narrower than that of self-amplified spontaneous emission (SASE), and additional monochromatization is needed. Here we compare L-edge x-ray absorption spectroscopy (XAS) of a prototypical transition metal system based on monochromatizing the SASE radiation of the linac coherent light source (LCLS) with a new technique based on self-seeding of LCLS. We demonstrate how L-edge XAS can be performed using the self-seeding scheme without the need of an additional beam line monochromator. We show how the spectral shape and pulse energy depend on the undulator setup and how this affects the x-ray spectroscopy measurements.

  9. Vibrational circular dichroism spectroscopy of a spin-triplet bis-(biuretato) cobaltate(III) coordination compound with low-lying electronic transitions

    DEFF Research Database (Denmark)

    Johannessen, Christian; Thulstrup, Peter W.

    2007-01-01

    Vibrational absorption (VA) and vibrational circular dichroism (VCD) spectroscopy was applied in the analysis of vibrational and low lying electronic transitions of a triplet ground state cobalt(III) coordination compound. The spectroscopic measurements were performed on the tetrabutylammonium salt...

  10. Electronic structure of metastable bcc Cu-Cr alloy thin films: Comparison of electron energy-loss spectroscopy and first-principles calculations.

    Science.gov (United States)

    Liebscher, C H; Freysoldt, C; Dennenwaldt, T; Harzer, T P; Dehm, G

    2017-07-01

    Metastable Cu-Cr alloy thin films with nominal thickness of 300nm and composition of Cu67Cr33 (at%) are obtained by co-evaporation using molecular beam epitaxy. The microstructure, chemical phase separation and electronic structure are investigated by transmission electron microscopy (TEM). The thin film adopts the body-centered cubic crystal structure and consists of columnar grains with ~50nm diameter. Aberration-corrected scanning TEM in combination with energy dispersive X-ray spectroscopy confirms compositional fluctuations within the grains. Cu- and Cr-rich domains with composition of Cu85Cr15 (at%) and Cu42Cr58 (at%) and domain size of 1-5nm are observed. The alignment of the interface between the Cu- and Cr-rich domains shows a preference for {110}-type habit plane. The electronic structure of the Cu-Cr thin films is investigated by electron energy loss spectroscopy (EELS) and is contrasted to an fcc-Cu reference sample. The experimental EEL spectra are compared to spectra computed by density functional theory. The main differences between bcc-and fcc-Cu are related to differences in van Hove singularities in the electron density of states. In Cu-Cr solid solutions with bcc crystal structure a single peak after the L3-edge, corresponding to a van Hove singularity at the N-point of the first Brillouin zone is observed. Spectra computed for pure bcc-Cu and random Cu-Cr solid solutions with 10at% Cr confirm the experimental observations. The calculated spectrum for a perfect Cu50Cr50 (at%) random structure shows a shift in the van Hove singularity towards higher energy by developing a Cu-Cr d-band that lies between the delocalized d-bands of Cu and Cr. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Secondary-electron-emission spectroscopy of tungsten: Angular dependence and phenomenology

    DEFF Research Database (Denmark)

    Willis, Roy F.; Christensen, Niels Egede

    1978-01-01

    Angle-resolved energy-distribution measurements of secondary-electron emission (SEE) from metals reveal spectral fine structure that relates directly to the density distribution of the one-electron states throughout E-K→ space located above the vacuum level Ev. The angular dependence of the SEE s...... to electron emission phenomenology of metal surfaces, thereby establishing a relationship with recently developed low-energy electron diffraction, photoemission, and field-emission formalism....

  12. Electronic structure simulation of chromium aluminum oxynitride by discrete variational-X alpha method and X-ray photoelectron spectroscopy

    CERN Document Server

    Choi, Y; Lee, J D; Kim, E; No, K

    2002-01-01

    We use a first-principles discrete variational (DV)-X alpha method to investigate the electronic structure of chromium aluminum oxynitride. When nitrogen is substituted for oxygen in the Cr-Al-O system, the N2p level appears in the energy range between O2p and Cr3d levels. Consequently, the valence band of chromium aluminum oxynitride becomes broader and the band gap becomes smaller than that of chromium aluminum oxide, which is consistent with the photoelectron spectra for the valence band using X-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS). We expect that this valence band structure of chromium aluminum oxynitride will modify the transmittance slope which is a requirement for photomask application.

  13. A facility for the analysis of the electronic structures of solids and their surfaces by synchrotron radiation photoelectron spectroscopy

    Science.gov (United States)

    Hoesch, M.; Kim, T. K.; Dudin, P.; Wang, H.; Scott, S.; Harris, P.; Patel, S.; Matthews, M.; Hawkins, D.; Alcock, S. G.; Richter, T.; Mudd, J. J.; Basham, M.; Pratt, L.; Leicester, P.; Longhi, E. C.; Tamai, A.; Baumberger, F.

    2017-01-01

    A synchrotron radiation beamline in the photon energy range of 18-240 eV and an electron spectroscopy end station have been constructed at the 3 GeV Diamond Light Source storage ring. The instrument features a variable polarisation undulator, a high resolution monochromator, a re-focussing system to form a beam spot of 50 × 50 μm2, and an end station for angle-resolved photoelectron spectroscopy (ARPES) including a 6-degrees-of-freedom cryogenic sample manipulator. The beamline design and its performance allow for a highly productive and precise use of the ARPES technique at an energy resolution of 10-15 meV for fast k-space mapping studies with a photon flux up to 2 ṡ 1013 ph/s and well below 3 meV for high resolution spectra.

  14. A facility for the analysis of the electronic structures of solids and their surfaces by synchrotron radiation photoelectron spectroscopy.

    Science.gov (United States)

    Hoesch, M; Kim, T K; Dudin, P; Wang, H; Scott, S; Harris, P; Patel, S; Matthews, M; Hawkins, D; Alcock, S G; Richter, T; Mudd, J J; Basham, M; Pratt, L; Leicester, P; Longhi, E C; Tamai, A; Baumberger, F

    2017-01-01

    A synchrotron radiation beamline in the photon energy range of 18-240 eV and an electron spectroscopy end station have been constructed at the 3 GeV Diamond Light Source storage ring. The instrument features a variable polarisation undulator, a high resolution monochromator, a re-focussing system to form a beam spot of 50 × 50 μm 2 , and an end station for angle-resolved photoelectron spectroscopy (ARPES) including a 6-degrees-of-freedom cryogenic sample manipulator. The beamline design and its performance allow for a highly productive and precise use of the ARPES technique at an energy resolution of 10-15 meV for fast k-space mapping studies with a photon flux up to 2 ⋅ 10 13 ph/s and well below 3 meV for high resolution spectra.

  15. A search for strong-field direct two electron ionization using coincidence spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Agostini, P.; Mevel, E.; Breger, P. (CEA Centre d' Etudes Nucleaires de Saclay, 91 - Gif-sur-Yvette (France). Service de Recherches sur les Surfaces et de l' Irradiation de la Matiere); Walker, B.; Yang, B.; DiMauro, L.F. (Brookhaven National Lab., Upton, NY (United States))

    1993-01-01

    We report on our program in detecting two-electron ionization using electron-electron and electron-ion coincidence measurements. The coincidence techniques have been applied to the multiphoton ionization (MPI) of xenon atoms with 0.527 [mu]m excitation. The results show that direct two electron ionization is not occurring which is in variance with an earlier report. We also present a polarization study on the MPI of helium at 0.62 [mu]m and discuss these results in context of existing models.

  16. A search for strong-field direct two electron ionization using coincidence spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Agostini, P.; Mevel, E.; Breger, P. [CEA Centre d`Etudes Nucleaires de Saclay, 91 - Gif-sur-Yvette (France). Service de Recherches sur les Surfaces et de l`Irradiation de la Matiere; Walker, B.; Yang, B.; DiMauro, L.F. [Brookhaven National Lab., Upton, NY (United States)

    1993-05-01

    We report on our program in detecting two-electron ionization using electron-electron and electron-ion coincidence measurements. The coincidence techniques have been applied to the multiphoton ionization (MPI) of xenon atoms with 0.527 {mu}m excitation. The results show that direct two electron ionization is not occurring which is in variance with an earlier report. We also present a polarization study on the MPI of helium at 0.62 {mu}m and discuss these results in context of existing models.

  17. X-ray spectroscopy an introduction

    CERN Document Server

    Agarwal, Bipin K

    1979-01-01

    Rontgen's discovery of X-rays in 1895 launched a subject which became central to the development of modern physics. The verification of many of the predic­ tions of quantum theory by X-ray spectroscopy in the early part of the twen­ tieth century stimulated great interest in thi's area, which has subsequently influenced fields as diverse as chemical physics, nuclear physics, and the study of the electronic properties of solids, and led to the development of techniques such as Auger, Raman, and X-ray photoelectron spectroscopy. The improvement of the theoretical understanding of the physics underlying X-ray spectroscopy has been accompanied by advances in experimental techniques, and the subject provides an instructive example of how progress on both these fronts can be mutually beneficial. This book strikes a balance between his­ torical description, which illustrates this symbiosis, and the discussion of new developments. The application of X-ray spectroscopic methods to the in­ vestigation of chemical b...

  18. Combined electron microscopy and vibrational spectroscopy study of corroded Magnox sludge from a legacy spent nuclear fuel storage pond

    Energy Technology Data Exchange (ETDEWEB)

    Gregson, Colin R., E-mail: colin.r.gregson@nnl.co.uk [National Nuclear Laboratory, Central Laboratory, Sellafield, Seascale CA20 1PG (United Kingdom); Goddard, David T., E-mail: dave.t.goddard@nnl.co.uk [National Nuclear Laboratory, Preston Laboratory, Springfields, Salwick, Preston PR4 0XJ (United Kingdom); Sarsfield, Mark J., E-mail: mark.j.sarsfield@nnl.co.uk [National Nuclear Laboratory, Central Laboratory, Sellafield, Seascale CA20 1PG (United Kingdom); Taylor, Robin J., E-mail: robin.j.taylor@nnl.co.uk [National Nuclear Laboratory, Central Laboratory, Sellafield, Seascale CA20 1PG (United Kingdom)

    2011-05-01

    Graphical abstract: Spent Magnox fuel corroding in-situ in storage ponds forms sludges comprised of brucite and other Mg based phases with uranium oxide particles. Display Omitted Research highlights: > Caracterization study of highly radioactive corroded Magnox sludges. > Unique data from samples of actual corroded nuclear fuel. > Combined electron microscopy and vibrational spectroscopy study. > Analysis of particles from legacy spent fuel storage pond at Sellafield. > Supports major UK decommissioning and nuclear clean up challenge. - Abstract: Samples of filtered particulates and sludges, formed from corroding magnesium alloy clad uranium metal ('Magnox') fuel elements, collected from one of the legacy nuclear fuel storage ponds located at Sellafield (UK) were investigated by Environmental Scanning Electron Microscopy with Energy Dispersive X-Ray analysis (ESEM/EDX), micro-Raman spectroscopy and Fourier transform infra-red spectroscopy (FT-IR). ESEM imaging confirmed the dominant morphology to be clusters of interlocking platelets typical of brucite (Mg(OH){sub 2}). EDX analysis was suggestive of some conversion to the related phase, hydrotalcite (Mg{sub 6}Al{sub 2}(CO{sub 3})(OH){sub 16}.4H{sub 2}O), due to elevated levels of Al associated with Mg. Other apparent morphologies were less commonly observed including flaky sheets, consistent with earlier stages of Magnox alloy corrosion. In a few specific cases, rods were also observed suggestive of some conversion to Mg-hydroxycarbonate phases. Discrete phases rich in U were also identified. Fluorescence in the Raman spectroscopy also indicated surface coatings of organic macromolecules and iron sulphide on hematite containing particles, attributed to microbial activity within the open air pond. Some specific differences in the solid phases between pond areas with differing conditions were apparent.

  19. Electron band bending and surface sensitivity: X-ray photoelectron spectroscopy of polar GaN surfaces

    Science.gov (United States)

    Bartoš, I.; Romanyuk, O.; Paskova, T.; Jiříček, P.

    2017-10-01

    The role of electron band bending and surface sensitivity in determining the core level binding energies by X-ray photoelectron spectroscopy is investigated. A dominating contribution of surface atomic layers to photoemission intensity is confirmed for normal photoemission. The energy of the photoelectron core level peak does not deviate from core level peak energies of electrons photoemitted from the surface atomic layers of the crystal. The higher surface sensitivity regime, achieved e.g. at off-normal photoelectron detection angle, can be used to study the surface potential barrier in just a few topmost atomic layers. In addition, it is demonstrated that core level binding energy measured by angle-resolved X-ray photoelectron spectroscopy reflect the electron attenuation anisotropy. In particular, core level binding energy changes with emission angle and correlates with the forward focusing directions in a crystal. This effect is demonstrated by measuring the polar angle dependence of Ga 3d core levels on clean GaN(0001) and GaN(000 1 bar) surfaces with a higher and a lower band bending, respectively. The effect is explained by variation of emission depth in a crystal for normal and off-normal photoelectron emission angles.

  20. Application of MCD spectroscopy and TD-DFT to endohedral metallofullerenes for characterization of their electronic transitions.

    Science.gov (United States)

    Yamada, Michio; Slanina, Zdenek; Mizorogi, Naomi; Muranaka, Atsuya; Maeda, Yutaka; Nagase, Shigeru; Akasaka, Takeshi; Kobayashi, Nagao

    2013-03-14

    We describe, for the first time, the application of magnetic circular dichroism (MCD) spectroscopy and time-dependent density functional theory (TD-DFT) calculations using B3LYP and M06-2X functionals to characterize the electronic transitions of endohedral metallofullerenes (EMFs). Results revealed that the electronic transitions of La@C(2v)-C(82), La(2)@I(h)-C(80), and Sc(3)N@I(h)-C(80) can be assigned using these techniques. Particularly, a difference in the electronic transitions between La(2)@I(h)-C(80) and Sc(3)N@I(h)-C(80), which is invisible in absorption spectra, was observed clearly in MCD spectra. The observed MCD bands agree well with the oscillator strengths calculated using the B3LYP functional. In addition, the MCD bands of La(2)@I(h)-C(80) were altered upon [5,6]-addition, demonstrating that the MCD spectroscopy is sensitive to chemical functionalization of EMFs, and that it is therefore powerful to distinguish [5,6]-adducts from pristine La(2)@I(h)-C(80), although no marked difference exists in their absorption spectra.

  1. Robust theoretical modelling of core ionisation edges for quantitative electron energy loss spectroscopy of B- and N-doped graphene

    Science.gov (United States)

    Hardcastle, T. P.; Seabourne, C. R.; Kepaptsoglou, D. M.; Susi, T.; Nicholls, R. J.; Brydson, R. M. D.; Scott, A. J.; Ramasse, Q. M.

    2017-06-01

    Electron energy loss spectroscopy (EELS) is a powerful tool for understanding the chemical structure of materials down to the atomic level, but challenges remain in accurately and quantitatively modelling the response. We compare comprehensive theoretical density functional theory (DFT) calculations of 1s core-level EEL K-edge spectra of pure, B-doped and N-doped graphene with and without a core-hole to previously published atomic-resolution experimental electron microscopy data. The ground state approximation is found in this specific system to perform consistently better than the frozen core-hole approximation. The impact of including or excluding a core-hole on the resultant theoretical band structures, densities of states, electron densities and EEL spectra were all thoroughly examined and compared. It is concluded that the frozen core-hole approximation exaggerates the effects of the core-hole in graphene and should be discarded in favour of the ground state approximation. These results are interpreted as an indicator of the overriding need for theorists to embrace many-body effects in the pursuit of accuracy in theoretical spectroscopy instead of a system-tailored approach whose approximations are selected empirically.

  2. The Central laser facility at the Pierre Auger Observatory

    Energy Technology Data Exchange (ETDEWEB)

    Arqueros, F.; Bellido, J.; Covault, C.; D' Urso, D.; Di Giulio, C.; Facal, P.; Fick, B.; Guarino, F.; Malek, M.; Matthews, J.A.J.; Matthews, J.; Meyhandan, R.; Monasor,; Mostafa, M.; Petrinca, P.; Roberts, M.; Sommers, P.; Travnicek, P.; Valore, L.; Verzi, V.; Wiencke, Lawrence; /Utah U.

    2005-07-01

    The Central Laser Facility is located near the middle of the Pierre Auger Observatory in Argentina. It features a UV laser and optics that direct a beam of calibrated pulsed light into the sky. Light scattered from this beam produces tracks in the Auger optical detectors which normally record nitrogen fluorescence tracks from cosmic ray air showers. The Central Laser Facility provides a ''test beam'' to investigate properties of the atmosphere and the fluorescence detectors. The laser can send light via optical fiber simultaneously to the nearest surface detector tank for hybrid timing analyses. We describe the facility and show some examples of its many uses.

  3. Mass sensitive observables of the Pierre Auger Observatory

    Directory of Open Access Journals (Sweden)

    Unger M.

    2013-06-01

    Full Text Available In this article we will discuss measurements of the longitudinal development of air showers at the Pierre Auger Observatory. The longitudinal development of the electromagnetic component can be directly observed by the fluorescence telescopes of the Auger Observatory and we will present the results on the evolution of the average shower maximum and its fluctuations as a function of energy. Moreover, two observables from the surface detector, the asymmetry of the rise time of the station signals and the muon production depth, will be discussed and the measurements will be compared to predictions from air shower simulations for different primary particle types.

  4. Thermal integrity profiling for augered cast-in-place piles – implementation plan : summary.

    Science.gov (United States)

    2017-09-01

    Auger-cast-in-place (ACIP) piles are created when an auger the diameter and length of the desired pile is drilled into the ground. Concrete is pumped through the central axis of the auger as it is withdrawn, pulling up excavated soil as concrete fill...

  5. Prototype muon detectors for the AMIGA component of the Pierre Auger Observatory

    Science.gov (United States)

    Aab, A.; Abreu, P.; Aglietta, M.; Ahn, E. J.; Samarai, I. Al; Albuquerque, I. F. M.; Allekotte, I.; Allison, P.; Almela, A.; Alvarez Castillo, J.; Alvarez-Muñiz, J.; Alves Batista, R.; Ambrosio, M.; Aminaei, A.; Anastasi, G. A.; Anchordoqui, L.; Andrada, B.; Andringa, S.; Aramo, C.; Arqueros, F.; Arsene, N.; Asorey, H.; Assis, P.; Aublin, J.; Avila, G.; Awal, N.; Badescu, A. M.; Baus, C.; Beatty, J. J.; Becker, K. H.; Bellido, J. A.; Berat, C.; Bertaina, M. E.; Bertou, X.; Biermann, P. L.; Billoir, P.; Blaess, S. G.; Blanco, A.; Blanco, M.; Blazek, J.; Bleve, C.; Blümer, H.; Boháčová, M.; Boncioli, D.; Bonifazi, C.; Borodai, N.; Botti, A. M.; Brack, J.; Brancus, I.; Bretz, T.; Bridgeman, A.; Brogueira, P.; Buchholz, P.; Bueno, A.; Buitink, S.; Buscemi, M.; Caballero-Mora, K. S.; Caccianiga, B.; Caccianiga, L.; Candusso, M.; Caramete, L.; Caruso, R.; Castellina, A.; Cataldi, G.; Cazon, L.; Cester, R.; Chavez, A. G.; Chiavassa, A.; Chinellato, J. A.; Chudoba, J.; Cilmo, M.; Clay, R. W.; Cocciolo, G.; Colalillo, R.; Coleman, A.; Collica, L.; Coluccia, M. R.; Conceição, R.; Contreras, F.; Cooper, M. J.; Cordier, A.; Coutu, S.; Covault, C. E.; Cronin, J.; Dallier, R.; Daniel, B.; Dasso, S.; Daumiller, K.; Dawson, B. R.; de Almeida, R. M.; de Jong, S. J.; De Mauro, G.; de Mello Neto, J. R. T.; De Mitri, I.; de Oliveira, J.; de Souza, V.; del Peral, L.; Deligny, O.; Dhital, N.; Di Giulio, C.; Di Matteo, A.; Diaz, J. C.; Díaz Castro, M. L.; Diogo, F.; Dobrigkeit, C.; Docters, W.; D'Olivo, J. C.; Dorofeev, A.; Dorosti Hasankiadeh, Q.; dos Anjos, R. C.; Dova, M. T.; Ebr, J.; Engel, R.; Erdmann, M.; Erfani, M.; Escobar, C. O.; Espadanal, J.; Etchegoyen, A.; Falcke, H.; Fang, K.; Farrar, G.; Fauth, A. C.; Fazzini, N.; Ferguson, A. P.; Fick, B.; Figueira, J. M.; Filevich, A.; Filipčič, A.; Fratu, O.; Freire, M. M.; Fujii, T.; Fuster, A.; Gallo, F.; García, B.; García-Gámez, D.; Garcia-Pinto, D.; Gate, F.; Gemmeke, H.; Gherghel-Lascu, A.; Ghia, P. L.; Giaccari, U.; Giammarchi, M.; Giller, M.; Głas, D.; Glaser, C.; Glass, H.; Golup, G.; Gómez Berisso, M.; Gómez Vitale, P. F.; González, N.; Gookin, B.; Gordon, J.; Gorgi, A.; Gorham, P.; Gouffon, P.; Griffith, N.; Grillo, A. F.; Grubb, T. D.; Guarino, F.; Guedes, G. P.; Hampel, M. R.; Hansen, P.; Harari, D.; Harrison, T. A.; Hartmann, S.; Harton, J. L.; Haungs, A.; Hebbeker, T.; Heck, D.; Heimann, P.; Hervé, A. E.; Hill, G. C.; Hojvat, C.; Hollon, N.; Holt, E.; Homola, P.; Hörandel, J. R.; Horvath, P.; Hrabovský, M.; Huber, D.; Huege, T.; Insolia, A.; Isar, P. G.; Jandt, I.; Jansen, S.; Jarne, C.; Johnsen, J. A.; Josebachuili, M.; Kääpä, A.; Kambeitz, O.; Kampert, K. H.; Kasper, P.; Katkov, I.; Keilhauer, B.; Kemp, E.; Kieckhafer, R. M.; Klages, H. O.; Kleifges, M.; Kleinfeller, J.; Krause, R.; Krohm, N.; Kuempel, D.; Kukec Mezek, G.; Kunka, N.; Kuotb Awad, A. W.; LaHurd, D.; Latronico, L.; Lauer, R.; Lauscher, M.; Lautridou, P.; Le Coz, S.; Lebrun, D.; Lebrun, P.; Leigui de Oliveira, M. A.; Letessier-Selvon, A.; Lhenry-Yvon, I.; Link, K.; Lopes, L.; López, R.; López Casado, A.; Louedec, K.; Lucero, A.; Malacari, M.; Mallamaci, M.; Maller, J.; Mandat, D.; Mantsch, P.; Mariazzi, A. G.; Marin, V.; Mariş, I. C.; Marsella, G.; Martello, D.; Martinez, H.; Martínez Bravo, O.; Martraire, D.; Masías Meza, J. J.; Mathes, H. J.; Mathys, S.; Matthews, J.; Matthews, J. A. J.; Matthiae, G.; Maurizio, D.; Mayotte, E.; Mazur, P. O.; Medina, C.; Medina-Tanco, G.; Meissner, R.; Mello, V. B. B.; Melo, D.; Menshikov, A.; Messina, S.; Micheletti, M. I.; Middendorf, L.; Minaya, I. A.; Miramonti, L.; Mitrica, B.; Molina-Bueno, L.; Mollerach, S.; Montanet, F.; Morello, C.; Mostafá, M.; Moura, C. A.; Müller, G.; Muller, M. A.; Müller, S.; Navas, S.; Necesal, P.; Nellen, L.; Nelles, A.; Neuser, J.; Nguyen, P. H.; Niculescu-Oglinzanu, M.; Niechciol, M.; Niemietz, L.; Niggemann, T.; Nitz, D.; Nosek, D.; Novotny, V.; Nožka, L.; Núñez, L. A.; Ochilo, L.; Oikonomou, F.; Olinto, A.; Pacheco, N.; Pakk Selmi-Dei, D.; Palatka, M.; Pallotta, J.; Papenbreer, P.; Parente, G.; Parra, A.; Paul, T.; Pech, M.; Pȩkala, J.; Pelayo, R.; Pepe, I. M.; Perrone, L.; Petermann, E.; Peters, C.; Petrera, S.; Petrov, Y.; Phuntsok, J.; Piegaia, R.; Pierog, T.; Pieroni, P.; Pimenta, M.; Pirronello, V.; Platino, M.; Plum, M.; Porcelli, A.; Porowski, C.; Prado, R. R.; Privitera, P.; Prouza, M.; Quel, E. J.; Querchfeld, S.; Quinn, S.; Rautenberg, J.; Ravel, O.; Ravignani, D.; Reinert, D.; Revenu, B.; Ridky, J.; Risse, M.; Ristori, P.; Rizi, V.; Rodrigues de Carvalho, W.; Rodriguez Rojo, J.; Rodríguez-Frías, M. D.; Rogozin, D.; Rosado, J.; Roth, M.; Roulet, E.; Rovero, A. C.; Saffi, S. J.; Saftoiu, A.; Salazar, H.; Saleh, A.; Salesa Greus, F.; Salina, G.; Sanabria Gomez, J. D.; Sánchez, F.; Sanchez-Lucas, P.; Santos, E. M.; Santos, E.; Sarazin, F.; Sarkar, B.; Sarmento, R.; Sarmiento-Cano, C.; Sato, R.; Scarso, C.; Schauer, M.; Scherini, V.; Schieler, H.; Schmidt, D.; Scholten, O.; Schoorlemmer, H.; Schovánek, P.; Schröder, F. G.; Schulz, A.; Schulz, J.; Schumacher, J.; Sciutto, S. J.; Segreto, A.; Settimo, M.; Shadkam, A.; Shellard, R. C.; Sigl, G.; Sima, O.; Śmiałkowski, A.; Šmída, R.; Snow, G. R.; Sommers, P.; Sonntag, S.; Sorokin, J.; Squartini, R.; Srivastava, Y. N.; Stanca, D.; Stanič, S.; Stapleton, J.; Stasielak, J.; Stephan, M.; Stutz, A.; Suarez, F.; Suarez Durán, M.; Suomijärvi, T.; Supanitsky, A. D.; Sutherland, M. S.; Swain, J.; Szadkowski, Z.; Taborda, O. A.; Tapia, A.; Tepe, A.; Theodoro, V. M.; Tibolla, O.; Timmermans, C.; Todero Peixoto, C. J.; Toma, G.; Tomankova, L.; Tomé, B.; Tonachini, A.; Torralba Elipe, G.; Torres Machado, D.; Travnicek, P.; Trini, M.; Ulrich, R.; Unger, M.; Urban, M.; Valdés Galicia, J. F.; Valiño, I.; Valore, L.; van Aar, G.; van Bodegom, P.; van den Berg, A. M.; van Velzen, S.; van Vliet, A.; Varela, E.; Vargas Cárdenas, B.; Varner, G.; Vasquez, R.; Vázquez, J. R.; Vázquez, R. A.; Veberič, D.; Verzi, V.; Vicha, J.; Videla, M.; Villaseñor, L.; Vlcek, B.; Vorobiov, S.; Wahlberg, H.; Wainberg, O.; Walz, D.; Watson, A. A.; Weber, M.; Weidenhaupt, K.; Weindl, A.; Werner, F.; Widom, A.; Wiencke, L.; Wilczyński, H.; Winchen, T.; Wittkowski, D.; Wundheiler, B.; Wykes, S.; Yang, L.; Yapici, T.; Yushkov, A.; Zas, E.; Zavrtanik, D.; Zavrtanik, M.; Zepeda, A.; Zimmermann, B.; Ziolkowski, M.; Zuccarello, F.

    2016-02-01

    AMIGA (Auger Muons and Infill for the Ground Array) is an upgrade of the Pierre Auger Observatory to extend its range of detection and to directly measure the muon content of the particle showers. It consists of an infill of surface water-Cherenkov detectors accompanied by buried scintillator detectors used for muon counting. The main objectives of the AMIGA engineering array, referred to as the Unitary Cell, are to identify and resolve all engineering issues as well as to understand the muon-number counting uncertainties related to the design of the detector. The mechanical design, fabrication and deployment processes of the muon counters of the Unitary Cell are described in this document. These muon counters modules comprise sealed PVC casings containing plastic scintillation bars, wavelength-shifter optical fibers, 64 pixel photomultiplier tubes, and acquisition electronics. The modules are buried approximately 2.25 m below ground level in order to minimize contamination from electromagnetic shower particles. The mechanical setup, which allows access to the electronics for maintenance, is also described in addition to tests of the modules' response and integrity. The completed Unitary Cell has measured a number of air showers of which a first analysis of a sample event is included here.

  6. Observation and spectroscopy of a two-electron Wigner molecule in an ultraclean carbon nanotube

    DEFF Research Database (Denmark)

    Pecker, S.; Kuemmeth, Ferdinand; Secchi, A.

    2013-01-01

    to be clearly imprinted on the energy spectrum, yet so far a direct measurement of such a spectrum in a controllable one-dimensional setting is still missing. Here we use an ultraclean carbon nanotube to realize this system in a tunable potential. Using tunnelling spectroscopy we measure the addition spectra...

  7. Adsorption and deposition of anthraquinone-2-carboxylic acid on alumina studied by inelastic electron tunneling spectroscopy, infrared reflection absorption spectroscopy, X-ray photoelectron spectroscopy, and atomic force microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Higo, Morihide [Department of Applied Chemistry and Chemical Engineering, Faculty of Engineering, Kagoshima University, 1-21-40 Korimoto, Kagoshima 890-0065 (Japan)], E-mail: higo@apc.kagoshima-u.ac.jp; Miake, Takeshi; Mitsushio, Masaru; Yoshidome, Toshifumi [Department of Applied Chemistry and Chemical Engineering, Faculty of Engineering, Kagoshima University, 1-21-40 Korimoto, Kagoshima 890-0065 (Japan); Ozono, Yoshihisa [Center for Instrumental analysis, Kagoshima University, 1-21-40 Korimoto, Kagoshima 890-0065 (Japan)

    2008-04-30

    The adsorption state of anthraquinone-2-carboxylic acid (AQ-2-COOH) deposited from acetone solutions (0.01-1.00 mg/ml) on native oxide surfaces of Al films was characterized by inelastic electron tunneling spectroscopy, infrared reflection absorption spectroscopy, and X-ray photoelectron spectroscopy. The oxide was prepared on evaporated Al films at room temperature in an oxygen-dc glow discharge. The morphology of the deposited AQ-2-COOH on the oxide surfaces was observed and analyzed by atomic force microscopy. These surface analyses showed that AQ-2-COOH is adsorbed predominantly as a uniform nanometer-scale film of carboxylate anions on the oxide surfaces deposited from solutions with concentrations lower than or equal to 0.02 mg/ml. It was found that AQ-2-COOH is adsorbed as both a uniform film of anions and as micron-sized particles of neutral molecules with heights of a few tens of nanometers when AQ-2-COOH is deposited from solutions with concentrations higher than 0.02 mg/ml. A comparison of the results obtained by these surface analytical techniques clearly shows the features and advantages of these analytical techniques.

  8. Towards a correlative approach for characterising single virus particles by transmission electron microscopy and nanoscale Raman spectroscopy.

    Science.gov (United States)

    Hermelink, A; Naumann, D; Piesker, J; Lasch, P; Laue, M; Hermann, P

    2017-04-10

    The morphology and structure of biological nanoparticles, such as viruses, can be efficiently analysed by transmission electron microscopy (TEM). To chemically characterise such nanoparticles in heterogeneous samples at the single particle level, we suggest tip-enhanced Raman spectroscopy (TERS) as a correlative method. Here we describe a TERS-compatible staining procedure for TEM which involves sample pre-scanning by TEM imaging, nanoparticle relocalisation by atomic force microscopy (AFM) followed by spectroscopic characterization of the virus nanoparticles using TERS. First successful correlative measurements are demonstrated on tobacco mosaic virus particles deposited on silicon-based TEM sample supports. In addition, the advantages and problems of this methodology are discussed.

  9. Electronic states localized at surface defects on Cu(755) studied by angle-resolved ultraviolet photoelectron spectroscopy using synchrotron radiation

    CERN Document Server

    Ogawa, K; Namba, H

    2003-01-01

    'Regularly stepped' and 'defective' surfaces of Cu(755) were prepared by low- and high-temperature annealing, respectively, of a clean specimen. Electronic states on both surfaces were studied by angle-resolved ultraviolet photoelectron spectroscopy using synchrotron radiation. On the defective Cu(755), we found a new photoelectron peak due to surface defects just below the Fermi level. The dispersion profile of the defect state is derived to be almost flat, which demonstrates the localized nature of the defects. High activity to oxygen adsorption of the defect state was revealed. (author)

  10. Strain analysis of plasma CVD graphene for roll-to-roll production by scanning transmission electron microscopy and Raman spectroscopy

    Science.gov (United States)

    Kato, Ryuichi; Koga, Yoshinori; Matsuishi, Kiyoto; Hasegawa, Masataka

    2017-03-01

    The establishment of the roll-to-roll CVD is one of the key factors for realizing the commercial application of graphene. The strain in graphene synthesized by high-throughput plasma CVD using two different conditions related to growth rate and tension to the substrate is analyzed by scanning transmission electron microscopy (STEM) and Raman spectroscopy. The compressive strain generated during the growth by the tension to the substrate and the difference in thermal expansion coefficient between the graphene and the copper substrate is observed, which affects electrical conductivity. It was confirmed by STEM observation that no particularly large strain was accumulated at grain boundaries and their surroundings.

  11. Characterization of gold nanoparticle films: Rutherford backscattering spectroscopy, scanning electron microscopy with image analysis, and atomic force microscopy

    Directory of Open Access Journals (Sweden)

    Pia C. Lansåker

    2014-10-01

    Full Text Available Gold nanoparticle films are of interest in several branches of science and technology, and accurate sample characterization is needed but technically demanding. We prepared such films by DC magnetron sputtering and recorded their mass thickness by Rutherford backscattering spectroscopy. The geometric thickness dg—from the substrate to the tops of the nanoparticles—was obtained by scanning electron microscopy (SEM combined with image analysis as well as by atomic force microscopy (AFM. The various techniques yielded an internally consistent characterization of the films. In particular, very similar results for dg were obtained by SEM with image analysis and by AFM.

  12. Soft X-ray spectroscopy of single sized CdS nanocrystals: size confinement and electronic structure

    Science.gov (United States)

    Lüning, J.; Rockenberger, J.; Eisebitt, S.; Rubensson, J.-E.; Karl, A.; Kornowski, A.; Weller, H.; Eberhardt, W.

    1999-08-01

    Soft X-ray spectroscopy of CdS nanocrystals within their crystalline superlattice allows to relate unambiguously, changes of the electronic structure with the particle size and shape which is known from single crystal X-ray diffraction. We find that the valence and conduction band edge shift contribute to the same extent to the total band gap opening of about 2 eV with respect to CdS bulk as the particle size decreases to 10 Å. Taking a finite height of the potential walls into account, we can reproduce these results within an effective mass approximation model.

  13. Full characterization of vibrational coherence in a porphyrin chromophore by two-dimensional electronic spectroscopy

    OpenAIRE

    Valduga de Almeida Camargo, Franco; Anderson, Harry; Meech, Steve; Heisler, Ismael

    2015-01-01

    In this work we present experimental and calculated two-dimensional electronic spectra for a 5,15-bisalkynyl porphyrin chromophore. The lowest energy electronic Qy transition couples mainly to a single 380 cm–1 vibrational mode. The two-dimensional electronic spectra reveal diagonal and cross peaks which oscillate as a function of population time. We analyze both the amplitude and phase distribution of this main vibronic transition as a function of excitation and detection frequencies. Even t...

  14. Photoionization and Velocity Map Imaging spectroscopy of atoms, molecules and clusters with Synchrotron and Free Electron Laser radiation at Elettra

    Science.gov (United States)

    Di Fraia, M.; Sergo, R.; Stebel, L.; Giuressi, D.; Cautero, G.; Tudor, M.; Callegari, C.; O'Keeffe, P.; Ovcharenko, Y.; Lyamayev, V.; Feyer, V.; Moise, A.; Devetta, M.; Piseri, P.; Grazioli, C.; Coreno, M.

    2015-12-01

    Advances in laser and Synchrotron Radiation instrumentation are continuously boosting fundamental research on the electronic structure of matter. At Elettra the collaboration between several groups active in the field of atomic, molecular and cluster physics and the Instrumentation and Detector Laboratory has resulted in an experimental set-up that successfully tackles the challenges posed by the investigation of the electronic structure of isolated species in the gas phase. The use of Synchrotron Radiation (SR) and Free Electron Laser (FEL) light, allows to cover a wide spectrum of targets from energetic to dynamics. We developed a Velocity Map Imaging (VMI) spectrometer that allows to perform as well SR as FEL experiments, just by changing part of the detection system. In SR experiments, at the Gasphase beamline of Elettra, a cross delay line detector is used, coupled to a 4-channel time-to-digital converter that reconstructs the position of the electrons. Simultaneously, a Time-of-Flight (TOF) mass spectrometer is used to acquire photoion spectra. Such a system allows PhotoElectron-PhotoIon-Coincidence (PEPICO) spectroscopy of atoms, molecules and clusters. In FEL experiments (notably differing from SR experiments in the much higher rate of events produced and detected, which forces one to forfeit coincidence detection), at the Low Density Matter (LDM) beamline of FERMI, a Micro Channel Plate (MCP) a phosphor screen and a CCD camera are used instead, capable of shot-by-shot collection of practically all events, albeit without time resolution.

  15. Screened-exchange density functional approach to Auger recombination and impact ionization rates in InGaAs

    Science.gov (United States)

    Picozzi, Silvia; Asahi, Ryoji; Geller, Clint; Freeman, Arthur

    2004-03-01

    We present an ab-initio modeling approach for Auger recombination and impact ionization in semiconductors directed at i) quantitative rate determinations and 2) elucidating trends with respect to alloy composition, carrier concentration and temperature. We present a fully first-principles formalism (S.Picozzi, R.Asahi, C.B. Geller and A.J.Freeman, Phys.Rev.Lett. 89, 197601 (2002); Phys.Rev.B 65, 113206 (2002).), based on accurate energy bands and wave functions within the screened exchange local density approximation and the full-potential linearized augmented plane wave (FLAPW) method (E.Wimmer, H.Krakauer, M.Weinert, A.J.Freeman, Phys.Rev.B 24, 864 (1981)). Results are presented for electron- and hole-initiated impact ionization processes and Auger recombinations for p-type and n-type InGaAs. Anisotropy and composition effects in the related rates are discussed in terms of the underlying band-structures. Calculated Auger lifetimes, in general agreement with experiments, are studied for different recombination mechanisms (i.e. CCCH, CHHL, CHHS, involving conduction electrons (C), heavy- (H) and light-hole (L), spin split-off (S) band) in order to understand the dominant mechanism.

  16. Metallic Na formation in NaCl crystals with irradiation of electron or vacuum ultraviolet photon

    Energy Technology Data Exchange (ETDEWEB)

    Owaki, Shigehiro [Osaka Prefecture Univ., Sakai, Osaka (Japan). Coll. of Integrated Arts and Sciences; Koyama, Shigeko; Takahashi, Masao; Kamada, Masao; Suzuki, Ryouichi

    1997-03-01

    Metallic Na was formed in NaCl single crystals with irradiation of a variety of radiation sources and analyzed the physical states with several methods. In the case of irradiation of 21 MeV electron pulses to the crystal blocks, the optical absorption and lifetime measurement of positron annihilation indicated appearance of Na clusters inside. Radiation effects of electron beam of 30 keV to the crystals in vacuum showed the appearance of not only metallic Na but atomic one during irradiation with Auger electron spectroscopy. Intense photon fluxes in vacuum ultraviolet region of synchrotron radiation were used as another source and an analyzing method of ultraviolet photoelectron spectroscopy. The results showed the metallic Na layered so thick that bulk plasmon can exist. (author)

  17. CTM4DOC : Electronic structure analysis from X-ray spectroscopy

    NARCIS (Netherlands)

    Delgado-Jaime, Mario Ulises; Zhang, Kaili; Vura-Weis, Josh; De Groot, Frank M F

    2016-01-01

    Two electronic structure descriptions, one based on orbitals and the other based on term symbols, have been implemented in a new Matlab-based program, CTM4DOC. The program includes a graphical user interface that allows the user to explore the dependence of details of electronic structure in

  18. Determining binding energies of valence-band electrons in insulators and semiconductors via lanthanide spectroscopy

    NARCIS (Netherlands)

    Dorenbos, P.

    2013-01-01

    Models and methods to determine the absolute binding energy of 4f-shell electrons in lanthanide dopants will be combined with data on the energy of electron transfer from the valence band to a lanthanide dopant. This work will show that it provides a powerful tool to determine the absolute binding

  19. Quantification of the boron speciation in alkali borosilicate glasses by electron energy loss spectroscopy

    DEFF Research Database (Denmark)

    Cheng, D.S.; Yang, G.; Zhao, Y.Q.

    2015-01-01

    Transmission electron microscopy and related analytical techniques have been widely used to study the microstructure of different materials. However, few research works have been performed in the field of glasses, possibly due to the electron-beam irradiation damage. In this paper, we have...

  20. A Mononuclear Mn(II) Pseudoclathrochelate Complex Studied by Multi-Frequency Electron-Paramagnetic-Resonance Spectroscopy.

    Science.gov (United States)

    Azarkh, Mykhailo; Penkova, Larysa V; Kats, Svitlana V; Varzatskii, Oleg A; Voloshin, Yan Z; Groenen, Edgar J J

    2014-03-06

    Knowledge of the correlation between structural and spectroscopic properties of transition-metal complexes is essential to deepen the understanding of their role in catalysis, molecular magnetism, and biological inorganic chemistry. It provides topological and, sometimes, functional insight with respect to the active site properties of metalloproteins. The electronic structure of a high-spin mononuclear Mn(II) pseudoclathrochelate complex has been investigated by electron-paramagnetic-resonance (EPR) spectroscopy at 9.5 and 275.7 GHz. A substantial, virtually axial zero-field splitting with D = -9.7 GHz (-0.32 cm(-1)) is found, which is the largest one reported to date for a Mn(II) complex with six nitrogen atoms in the first coordination sphere.

  1. A study of internal oxidation in carburized steels by glow discharge optical emission spectroscopy and scanning electron microscopy

    CERN Document Server

    An, X; Rainforth, W M; Chen, L

    2003-01-01

    The internal oxidation of Cr-Mn carburizing steel was studied. Internal oxidation was induced using a commercial carburizing process. Sputter erosion coupled with glow discharge optical emission spectroscopy (GDOES) was used to determine the depth profile elemental distribution within the internal oxidation layer (<10 mu m). In addition, scanning electron microscopy (SEM) equipped with energy dispersive spectrometer (EDS) studies were carried out on selected sputter eroded surfaces. Oxide type was identified primarily by transmission electron microscopy (TEM). The carburized surface was found to consist of a continuous oxide layer, followed by a complex internal oxidation layer, where Cr and Mn oxides were found to populate grain boundaries in a globular form in the near surface region. At greater depths (5-10 mu m), Si oxides formed as a grain boundary network. The internal oxides (mainly complex oxides) grew quickly during the initial stages of the carburizing process (2 h, 800 deg. C+3 h, 930 deg. C). G...

  2. Electronic “Edge” State on Molybdenite Basal Plane Observed by Ultrahigh-Vacuum Scanning Tunneling Microscopy and Spectroscopy

    Science.gov (United States)

    Komiyama, Masaharu; Tomita, Hiroyuki; Yoda, Eisuke

    2007-09-01

    An electronic state heretofore unreported has been found on a cleaved basal plane of a natural molybdenite (MoS2) single crystal by ultrahigh-vacuum scanning tunneling microscopy (UHV-STM), and examined in detail both by STM and scanning tunneling spectroscopy (STS). The new electronic state resides on the edge of the upper terrace of MoS2(0001), manifesting itself in the form of bright ridges with a width of ca. 4 nm along the step edges in negatively sample-biased STM images. This ridge structure is nonexistent in STM images taken with positive sample biases. STS showed that the local density of states (LDOS) on such ridge structures is much higher than that on the terraces in the range of 0.2-1.2 eV below the Fermi edge. The nature and origin of this high LDOS at the step edges are discussed.

  3. Two-Dimensional Electronic-Vibrational Spectroscopy of Chlorophyll a and b

    Energy Technology Data Exchange (ETDEWEB)

    Lewis, Nicholas H. C. [Univ. of California, Berkeley, CA (United States). Dept. of Chemistry; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Molecular Biophysics and Integrated Bioimaging Div.; Kavli Energy Nanoscience Institute at Berkeley, CA (United States); Fleming, Graham R. [Univ. of California, Berkeley, CA (United States). Dept. of Chemistry; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Molecular Biophysics and Integrated Bioimaging Div.; Kavli Energy Nanoscience Institute at Berkeley, CA (United States)

    2016-03-03

    Presented are two-dimensional electronic-vibrational (2DEV) spectra of isolated chlorophyll a and b in deuterated ethanol. We excite the Q-band electronic transitions and measure the effects on the carbonyl and C=C double-bond stretch region of the infrared spectrum. With the aid of density functional theory calculations, we provide assignments for the major features of the spectrum. We show how the 2DEV spectra can be used to readily distinguish different solvation states of the chlorophyll, with features corresponding to the minority pentacoordinate magnesium (Mg) species being resolved along each dimension of the 2DEV spectra from the dominant hexacoordinate Mg species. These assignments represent a crucial first step toward the application of 2DEV spectroscopy to chlorophyll-containing pigment-protein complexes.

  4. Analysis of the fine structure of Sn$^{11+...14+}$ ions by optical spectroscopy in an electron beam ion trap

    CERN Document Server

    Windberger, A; Borschevsky, A; Ryabtsev, A; Dobrodey, S; Bekker, H; Eliav, E; Kaldor, U; Ubachs, W; Hoekstra, R; López-Urrutia, J R Crespo; Versolato, O O

    2016-01-01

    We experimentally re-evaluate the fine structure of Sn$^{11+...14+}$ ions. These ions are essential in bright extreme-ultraviolet (EUV) plasma-light sources for next-generation nanolithography, but their complex electronic structure is an open challenge for both theory and experiment. We combine optical spectroscopy of magnetic dipole $M1$ transitions, in a wavelength range covering 260\\,nm to 780\\,nm, with charge-state selective ionization in an electron beam ion trap. Our measurements confirm the predictive power of \\emph{ab initio} calculations based on Fock space coupled cluster theory. We validate our line identification using semi-empirical Cowan calculations with adjustable wavefunction parameters. Available Ritz combinations further strengthen our analysis. Comparison with previous work suggests that line identifications in the EUV need to be revisited.

  5. Review of the theoretical description of time-resolved angle-resolved photoemission spectroscopy in electron-phonon mediated superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Kemper, A.F. [Department of Physics, North Carolina State University, Raleigh, NC (United States); Sentef, M.A. [Max Planck Institute for the Structure and Dynamics of Matter, Center for Free Electron Laser Science, Hamburg (Germany); Moritz, B. [Stanford Institute for Materials and Energy Sciences (SIMES), SLAC National Accelerator Laboratory, Menlo Park, CA (United States); Devereaux, T.P. [Stanford Institute for Materials and Energy Sciences (SIMES), SLAC National Accelerator Laboratory, Menlo Park, CA (United States); Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA (United States); Freericks, J.K. [Department of Physics, Georgetown University, Washington, DC (United States)

    2017-09-15

    We review recent work on the theory for pump/probe photoemission spectroscopy of electron-phonon mediated superconductors in both the normal and the superconducting states. We describe the formal developments that allow one to solve the Migdal-Eliashberg theory in nonequilibrium for an ultrashort laser pumping field, and explore the solutions which illustrate the relaxation as energy is transferred from electrons to phonons. We focus on exact results emanating from sum rules and approximate numerical results which describe rules of thumb for relaxation processes. In addition, in the superconducting state, we describe how Anderson-Higgs oscillations can be excited due to the nonlinear coupling with the electric field and describe mechanisms where pumping the system enhances superconductivity. (copyright 2017 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  6. Polarity determination by electron energy-loss spectroscopy: application to ultra-small III-nitride semiconductor nanocolumns

    Energy Technology Data Exchange (ETDEWEB)

    Kong, X; Trampert, A [Paul-Drude-Institut fuer Festkoerperelektronik, Hausvogteiplatz 5-7, D-10117 Berlin (Germany); Ristic, J; Sanchez-Garcia, M A; Calleja, E [Departamento IngenierIa Electronica, ETSI Telecomunicacion, Universidad Politecnica, Ciudad Universitaria, E-28040 Madrid (Spain)

    2011-10-14

    Channeling-enhanced electron energy-loss spectroscopy is applied to determine the polarity of ultra-small nitride semiconductor nanocolumns in transmission electron microscopy. The technique demonstrates some practical advantages in the nanostructure analysis, especially for feature sizes of less than 50 nm. We have studied GaN and (Al, Ga)N nanocolumns grown in a self-assembled way by molecular beam epitaxy directly on bare Si(111) substrates and on AlN buffer layers, respectively. The GaN nanocolumns on Si show an N polarity, while the (Al, Ga)N nanocolumns on an AlN buffer exhibit a Ga polarity. The different polarities of nanocolumns grown in a similar procedure are interpreted in terms of the specific interface bonding configurations. Our investigation contributes to the understanding of polarity control in III-nitride nanocolumn growth.

  7. Interaction of H{sub 2}O molecules with Fe films investigated with metastable induced electron spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Volgmann, Kai [Institut fuer Festkoerperphysik, Leibniz Universitaet Hannover, Appelstr. 2, 30167 Hannover (Germany); Institut fuer Physik u. Phys. Technologien, TU Clausthal, Leibnizstr. 4, 38678 Clausthal-Zellerfeld (Germany); Voigts, Florian [Institut fuer Physik u. Phys. Technologien, TU Clausthal, Leibnizstr. 4, 38678 Clausthal-Zellerfeld (Germany); Maus-Friedrichs, Wolfgang [Institut fuer Physik u. Phys. Technologien, TU Clausthal, Leibnizstr. 4, 38678 Clausthal-Zellerfeld (Germany); Clausthaler Zentrum fuer Materialtechnik, TU Clausthal, Leibnizstr. 4, 38678 Clausthal-Zellerfeld (Germany)

    2011-07-01

    The formation of an oxide layer on Fe films upon the interaction with H{sub 2}O molecules is relevant for both applications and in surface science. This work examines the interaction of H{sub 2}O molecules with Fe films grown on a tungsten substrate. X-ray Photoelectron Spectroscopy is used to determine the stoichiometry of the samples, while Ultraviolet Photoelectron Spectroscopy and Metastable Induced Electron Spectroscopy (MIES) are used to analyse their valence band region and to gain information about changes in the work function because of reactions on the surface. All measurements are done at room temperature. MIES is used as a very surface sensitive technique, especially towards hydroxide groups. Only after a high H{sub 2}O exposure, we observed the formation of OH groups. Our previous experiments reveal that a passivating oxide layer is formed during oxygen offer to a Fe surface. A similar oxide layer growth may be observed during H{sub 2}O offer to iron. This oxide layer forms prior to the development of any observable OH groups.

  8. Electronic structure of metastable bcc Cu–Cr alloy thin films: Comparison of electron energy-loss spectroscopy and first-principles calculations

    Energy Technology Data Exchange (ETDEWEB)

    Liebscher, C.H.; Freysoldt, C. [Max-Planck-Institut für Eisenforschung GmbH, 40237 Düsseldorf (Germany); Dennenwaldt, T. [Institute of Condensed Matter Physics and Interdisciplinary Center for Electron Microscopy, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne (Switzerland); Harzer, T.P.; Dehm, G. [Max-Planck-Institut für Eisenforschung GmbH, 40237 Düsseldorf (Germany)

    2017-07-15

    Metastable Cu–Cr alloy thin films with nominal thickness of 300 nm and composition of Cu{sub 67}Cr{sub 33} (at%) are obtained by co-evaporation using molecular beam epitaxy. The microstructure, chemical phase separation and electronic structure are investigated by transmission electron microscopy (TEM). The thin film adopts the body-centered cubic crystal structure and consists of columnar grains with ~50 nm diameter. Aberration-corrected scanning TEM in combination with energy dispersive X-ray spectroscopy confirms compositional fluctuations within the grains. Cu- and Cr-rich domains with composition of Cu{sub 85}Cr{sub 15} (at%) and Cu{sub 42}Cr{sub 58} (at%) and domain size of 1–5 nm are observed. The alignment of the interface between the Cu- and Cr-rich domains shows a preference for {110}-type habit plane. The electronic structure of the Cu–Cr thin films is investigated by electron energy loss spectroscopy (EELS) and is contrasted to an fcc-Cu reference sample. The experimental EEL spectra are compared to spectra computed by density functional theory. The main differences between bcc-and fcc-Cu are related to differences in van Hove singularities in the electron density of states. In Cu–Cr solid solutions with bcc crystal structure a single peak after the L{sub 3}-edge, corresponding to a van Hove singularity at the N-point of the first Brillouin zone is observed. Spectra computed for pure bcc-Cu and random Cu–Cr solid solutions with 10 at% Cr confirm the experimental observations. The calculated spectrum for a perfect Cu{sub 50}Cr{sub 50} (at%) random structure shows a shift in the van Hove singularity towards higher energy by developing a Cu–Cr d-band that lies between the delocalized d-bands of Cu and Cr. - Highlights: • Compositional fluctuations on the order of 1–5 nm in Cu- and Cr-rich domains are observed. • EELS determines a single van Hove singularity for bcc Cu–Cr solid solutions. • The electronic structure is dominated by d

  9. Raman spectroscopy as a tool to investigate the structure and electronic properties of carbon-atom wires

    Directory of Open Access Journals (Sweden)

    Alberto Milani

    2015-02-01

    Full Text Available Graphene, nanotubes and other carbon nanostructures have shown potential as candidates for advanced technological applications due to the different coordination of carbon atoms and to the possibility of π-conjugation. In this context, atomic-scale wires comprised of sp-hybridized carbon atoms represent ideal 1D systems to potentially downscale devices to the atomic level. Carbon-atom wires (CAWs can be arranged in two possible structures: a sequence of double bonds (cumulenes, resulting in a 1D metal, or an alternating sequence of single–triple bonds (polyynes, expected to show semiconducting properties. The electronic and optical properties of CAWs can be finely tuned by controlling the wire length (i.e., the number of carbon atoms and the type of termination (e.g., atom, molecular group or nanostructure. Although linear, sp-hybridized carbon systems are still considered elusive and unstable materials, a number of nanostructures consisting of sp-carbon wires have been produced and characterized to date. In this short review, we present the main CAW synthesis techniques and stabilization strategies and we discuss the current status of the understanding of their structural, electronic and vibrational properties with particular attention to how these properties are related to one another. We focus on the use of vibrational spectroscopy to provide information on the structural and electronic properties of the system (e.g., determination of wire length. Moreover, by employing Raman spectroscopy and surface enhanced Raman scattering in combination with the support of first principles calculations, we show that a detailed understanding of the charge transfer between CAWs and metal nanoparticles may open the possibility to tune the electronic structure from alternating to equalized bonds.

  10. Reflection electron energy loss spectroscopy as efficient technique for the determination of optical properties of polystyrene intermixed with gold nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Deris, Jamileh [Department of Physics, Yasouj University, Yasouj 75918-74831 (Iran, Islamic Republic of); Hajati, Shaaker, E-mail: Hajati@mail.yu.ac.ir [Department of Physics, Yasouj University, Yasouj 75918-74831 (Iran, Islamic Republic of); Department of Semiconductors, Materials and Energy Research Center, Karaj 3177983634 (Iran, Islamic Republic of)

    2017-01-15

    Highlights: • Reflection Electron Energy Loss Spectroscopy of nano-metalized polymer. • Determination of real part of the dielectric function of nanostructured sample. • Determination of imaginary part of the dielectric function of nanostructured sample. • Determination of refractive index and coefficient of extinction of the sample. • Determination of reflection and absorption coefficients of nano-metalized Polymer. - Abstract: The electronic properties (electron inelastic cross section, energy loss function) of a nano-metalized polystyrene obtained by reflection electron energy loss spectroscopy (REELS) in a previous study [J. Deris, S. Hajati, S. Tougaard, V. Zaporojtchenko, Appl. Surf. Sci. 377 (2016) 44–47], which relies on the Yubero-Tougaard method, were used in the complementary application of Kramers-Kronig transformation to determine its optical properties such as the real part (ε{sub 1}) and imaginary part (ε{sub 2}) of the dielectric function (ε), refractive index (n), coefficients of extinction (k), reflection (R) and absorption (μ). The degree of intermixing of polystyrene thin film and gold nanoparticles of sizes 5.5 nm was controlled by annealing the sample to achieve a morphology in which the nanoparticles were homogeneously distributed within polystyrene. It is worth noting that no data are available on the optical properties of metalized polymers such as gold nanoparticles intermixed with polystyrene. Therefore, this work is of high importance in terms of both the sample studied here and the method applied. The advantage of the method applied here is that no information on the lateral distribution of the nanocomposite sample is required. This means that the REELS technique has been presented here to suitably, efficiently and easily obtain the optical properties of such nano-metalized polymer in which the metal nanoparticles have been vertically well distributed (homogeneous in depth). Therefore, for vertically homogeneous and

  11. Emission Mössbauer spectroscopy of advanced materials for opto- and nano-electronics

    CERN Multimedia

    Olafsson, S; Weyer, G O P; Masenda, H; Dlamini, W B

    Mössbauer Spectroscopy (MS) is a versatile solid state method giving information about probe atom interactions with its nearest neighbours. Simultaneously, information on the probe valence state, site symmetry, and electric and magnetic hyperfine interactions is obtained. MS can be applied in many different contexts in material science and solid state physics. MS using radioactive isotopes, applied for decades at the ISOLDE facilities, has the particular merit of very high sensitivity. This opens up many new possibilities compared to traditional (absorption) Mössbauer spectroscopy. Among them is the possibility of working with very low concentrations (10$^{-4}$ at. ~\\%), where the probe atoms are true dilute impurities. Here we propose four main themes in our Mössbauer investigations for the coming years: \\\\(1) Para-magnetic relaxations in compound semiconductors. \\\\(2) Vacancy diffusion in group IV semiconductors. \\\\(3) Doping of Si-nano-particles. \\\\(4) Investigation of phase change mechanisms in chalcog...

  12. Analysis of the Quintilii’s Villa Bronzes by Spectroscopy Techniques

    Directory of Open Access Journals (Sweden)

    Fabio Stranges

    2014-01-01

    Full Text Available The aim of this work is the characterization, with different diagnostic tests, of three fragments of bronze artefacts recovered from the Villa of the Quintilii (located in the south of Rome. In particular, the sample alloys were investigated by different chemical and morphological analysis. Firstly, an analysis of the alloy, implemented through the electronic spectroscopy, was taken to discriminate the bronze morphology and its elemental composition. Subsequently, a surface analysis was realized by molecular spectroscopy to identify the alteration patinas on surfaces (such as bronze disease. Two diagnostic techniques are used for the alloy analysis: scanning electron microscopy (SEM connected to the EDX spectroscopy (to study the morphology and alloy composition and Auger electron spectroscopy (AES (to identify the oxidation state of each element. Moreover, for the study of surface patinas, IR and Raman spectroscopies were implemented. All studies were performed on the “as received” samples, covered by a thin layer of excavated soil and on samples processed in an aqueous solution of sulphuric acid (10%, to remove patinas and alterations.

  13. Direct Probing of Photoinduced Electron Transfer in a Self-Assembled Biomimetic [2Fe2S]-Hydrogenase Complex Using Ultrafast Vibrational Spectroscopy

    NARCIS (Netherlands)

    Li, P.; Amirjalayer, S.; Hartl, F.; Lutz, M.; de Bruin, B.; Becker, R.; Woutersen, S.; Reek, J.N.H.

    2014-01-01

    Photoinduced electron transfer in a supramolecular ZnTPP·Fe2S2 complex is investigated using femtosecond infrared spectroscopy, infrared spectro-electrochemistry, and DFT calculations. We find that the electron density is delocalized over the diiron core and the naphthalimide ligand, which explains

  14. The Pierre Auger Observatory status and latest results

    Science.gov (United States)

    Berat, Corinne

    2017-03-01

    The Pierre Auger Observatory, in Argentina, is the present flagship experiment studying ultrahigh-energy cosmic rays (UHECRs). Facing the challenge due to low cosmic-ray flux at the highest energies, the Observatory has been taking data for more than a decade, reaching an exposure of over 50 000 km2 sr yr. The combination of a large surface detector array and fluorescence telescopes provides a substantial improvement in energy calibration and extensive air shower measurements, resulting in data of unprecedented quality. Moreover, the installation of a denser subarray has allowed extending the sensitivity to lower energies. Altogether, this contributes to provide important information on key questions in the UHECR field in the energy range from 0.1 EeV up to 100 EeV. A review of main results from the Pierre Auger Observatory is presented with a particular focus on the energy spectrum measurements, the mass composition studies, the arrival directions analyses, the search for neutral cosmic messengers, and the investigation of high-energy hadronic interactions. Despite this large amount of valuable results, the understanding of the nature of UHECRs and of their origin remains an open science case that the Auger collaboration is planning to address with the AugerPrime project to upgrade the Observatory.

  15. development of a computer program for the design of auger

    African Journals Online (AJOL)

    User

    Computer Science Department, U.N.N.. E- mail: ugwuishiwubo@yahoo.co.uk. ABSTRACT. The screw or auger conveyor is an important conveyor in agricultural and food processing industries. The classical approach to its analysis and design involve the determination of the type and dimensions of the pitch, capacity, screw ...

  16. Search for ultrarelativistic magnetic monopoles with the Pierre Auger observatory

    NARCIS (Netherlands)

    Aab, A.; Abreu, P.; Aglietta, M.; Al Samarai, I.; Albuquerque, I. F. M.; Allekotte, I.; Almela, A.; Alvarez Castillo, J.; Alvarez-Muniz, J.; Ambrosio, M.; Anastasi, G. A.; Anchordoqui, L.; Andrada, B.; Andringa, S.; Aramo, C.; Arqueros, F.; Arsene, N.; Asorey, H.; Assis, P.; Aublin, J.; Avila, G.; Badescu, A. M.; Balaceanu, A.; Barreira Luz, R. J.; Baus, C.; Beatty, J. J.; Becker, K. H.; Bellido, J. A.; Berat, C.; Bertaina, E.; Bertou, X.; Biermann, P. L.; Billoir, P.; Biteau, J.; Blaess, S. G.; Blanco, A.; Blazek, J.; Bleve, C.; Bohacova, M.; Boncioli, D.; Bonifazi, C.; Borodai, N.; Botti, A. M.; Brack, J.; Brancus, I.; Bretz, T.; Bridgeman, A.; Briechle, F. L.; Buchholz, P.; Bueno, A.; Buitink, S.; Buscemi, M.; Caballero-Mora, K. S.; Caccianiga, L.; Cancio, A.; Canfora, F.; Caramete, L.; Caruso, R.; Castellina, A.; Cataldi, G.; Cazon, L.; Cester, R.; Chavez, A. G.; Chinellato, J. A.; Chudoba, J.; Clay, R. W.; Colalillo, R.; Coleman, A.; Collica, L.; Coluccia, M. R.; Conceicao, R.; Contreras, F.; Cooper, M. J.; Coutu, S.; Covault, C. E.; Cronin, J.; D'Amico, S.; Daniel, B.; Dasso, S.; Daumiller, K.; Dawson, B. R.; de Almeida, R. M.; de Jong, S. J.; De Mauro, G.; de Mello Neto, J. R. T.; De Mitri, I.; De Oliveira, J.; de Souza, V.; Debatin, J.; Deligny, O.; Di Giulio, C.; Di Matteo, A.; Diaz Castro, M. L.; Diogo, F.; Dobrigkeit, C.; D'Olivo, J. C.; Dorofeev, A.; dos Anjos, R. C.; Dova, M. T.; Dundovic, A.; Ebr, J.; Engel, R.; Erdmann, M.; Erfani, M.; Escobar, C. O.; Espadanal, J.; Etchegoyen, A.; Falcke, H.; Fang, K.; Farrar, G.; Fauth, A. C.; Fazzini, N.; Fick, B.; Figueira, J. M.; Filipcic, A.; Fratu, O.; Freire, M. M.; Fujii, T.; Fuster, A.; Gaior, R.; Garcia, B.; Garcia-Pinto, D.; Gate, F.; Gemmeke, H.; Gherghel-Lascu, A.; Ghia, P. L.; Giaccari, U.; Giammarchi, M.; Giller, M.; Glas, D.; Glaser, C.; Glass, H.; Golup, G.; Gomez Berisso, M.; Gomez Vitale, P. F.; Gonzalez, N.; Gookin, B.; Gorgi, A.; Gorham, P.; Gouffon, P.; Grillo, A. F.; Grubb, T. D.; Guarino, F.; Guedes, G. P.; Hampel, M. R.; Hansen, P.; Harari, D.; Harrison, T. A.; Harton, J. L.; Dorosti Hasankiadeh, Qader; Haungs, A.; Hebbeker, T.; Heck, D.; Heimann, P.; Herve, A. E.; Hill, G. C.; Hojvat, C.; Holt, E.; Homola, P.; Horandel, J. R.; Horvath, P.; Hrabovsky, M.; Huege, T.; Hulsman, J.; Insolia, A.; Isar, P. G.; Jandt, I.; Jansen, S.; Johnsen, J. A.; Josebachuili, M.; Kaeaepae, A.; Kambeitz, O.; Kampert, K. H.; Kasper, P.; Katkov, I.; Keilhauer, B.; Kemp, E.; Kemp, J.; Kieckhafer, R. M.; Klages, H. O.; Kleifges, M.; Kleinfeller, J.; Krause, R.; Krohm, N.; Kuempel, D.; Mezek, G. Kukec; Kunka, N.; Awad, A. Kuotb; LaHurd, D.; Lauscher, M.; Lebrun, P.; Legumina, R.; Leigui de Oliveira, M. A.; Letessier-Selvon, A.; Lhenry-Yvon, I.; Link, K.; Lopes, L.; Lopez, R.; Lopez Casado, A.; Luce, Q.; Lucero, A.; Malacari, M.; Mallamaci, M.; Mandat, D.; Mantsch, P.; Mariazzi, A. G.; Maris, I. C.; Marsella, G.; Martello, D.; Martinez, H.; Martinez Bravo, O.; Masias Meza, J. J.; Mathes, H. J.; Mathys, S.; Matthews, J.; Matthews, J. A. J.; Matthiae, G.; Mayotte, E.; Mazur, P. O.; Medina, C.; Medina-Tanco, G.; Melo, D.; Menshikov, A.; Messina, S.; Micheletti, M. I.; Middendorf, L.; Minaya, I. A.; Miramonti, L.; Mitrica, B.; Mockler, D.; Molina-Bueno, L.; Mollerach, S.; Montanet, F.; Morello, C.; Mostafa, M.; Mueller, G.; Muller, M. A.; Mueller, S.; Naranjo, I.; Nellen, L.; Neuser, J.; Nguyen, P. H.; Niculescu-Oglinzanu, M.; Niechciol, M.; Niemietz, L.; Niggemann, T.; Nitz, D.; Nosek, D.; Novotny, V.; Nozka, H.; Nunez, L. A.; Ochilo, L.; Oikonomou, F.; Olinto, A.; Pakk Selmi-Dei, D.; Palatka, M.; Pallotta, J.; Papenbreer, P.; Parente, G.; Parra, A.; Paul, T.; Pech, M.; Pedreira, F.; Kala, J. Pe; Pelayo, R.; Pena-Rodriguez, J.; Pereira, L. A. S.; Perrone, L.; Peters, C.; Petrera, S.; Phuntsok, J.; Piegaia, R.; Pierog, T.; Pieroni, P.; Pimenta, M.; Pirronello, V.; Platino, M.; Plum, M.; Porowski, C.; Prado, R. R.; Privitera, P.; Prouza, M.; Quel, E. J.; Querchfeld, S.; Quinn, S.; Ramos-Pollan, R.; Rautenberg, J.; Ravignani, D.; Reinert, D.; Revenu, B.; Ridky, J.; Risse, M.; Ristori, P.; Rizi, V.; Rodrigues de Carvalho, W.; Fernandez, G. Rodriguez; Rodriguez Rojo, J.; Rogozin, D.; Roth, M.; Roulet, E.; Rovero, A. C.; Saffi, S. J.; Saftoiu, A.; Salamida, F.; Salazar, H.; Saleh, A.; Greus, F. Salesa; Salina, G.; Sanabria Gomez, J. D.; Sanchez, F.; Sanchez-Lucas, P.; Santos, E. M.; Santos, E.; Sarazin, F.; Sarkar, B.; Sarmento, R.; Sarmiento, C. A.; Sato, R.; Schauer, M.; Scherini, V.; Schieler, H.; Schimp, M.; Schmidt, D.; Scholten, O.; Schovanek, P.; Schroder, F. G.; Schulz, A.; Schulz, J.; Schumacher, J.; Sciutto, S. J.; Segreto, A.; Settimo, M.; Shadkam, A.; Shellard, R. C.; Sigl, G.; Silli, G.; Sima, O.; Smialkowski, A.; Smida, R.; Snow, G. R.; Sommers, P.; Sonntag, S.; Sorokin, J.; Squartini, R.; Stanca, D.; Stanic, S.; Stasielak, J.; Stassi, P.; Strafella, F.; Suarez, F.; Suarez Duran, M.; Sudholz, T.; Suomijarvi, T.; Supanitsky, A. D.; Swain, J.; Szadkowski, Z.; Taboada, A.; Taborda, O. A.; Tapia, A.; Theodoro, V. M.; Timmermans, C.; Todero Peixoto, C. J.; Tomankova, L.; Tome, B.; Torralba Elipe, G.; Torres Machado, D.; Torri, M.; Travnicek, P.; Trini, M.; Ulrich, R.; Unger, M.; Urban, M.; Valdes Galicia, J. F.; Valino, I.; Valore, L.; van Aar, G.; van Bodegom, P.; van den Berg, A. M.; van Vliet, A.; Varela, E.; Vargas Cardenas, B.; Varner, G.; Vazquez, J. R.; Vazquez, R. A.; Veberic, D.; Vergara Quispe, I. D.; Verzi, V.; Vicha, J.; Villasenor, L.; Vorobiov, S.; Wahlberg, H.; Wainberg, O.; Walz, D.; Watson, A. A.; Weber, M.; Weindl, A.; Wiencke, L.; Wilczynski, H.; Winchen, T.; Wittkowski, D.; Wundheiler, B.; Wykes, S.; Yang, L.; Yelos, D.; Yushkov, A.; Zas, E.; Zavrtanik, D.; Zavrtanik, M.; Zepeda, A.; Zimmermann, B.; Ziolkowski, M.; Zong, Z.; Zuccarello, F.

    2016-01-01

    We present a search for ultrarelativistic magnetic monopoles with the Pierre Auger observatory. Such particles, possibly a relic of phase transitions in the early Universe, would deposit a large amount of energy along their path through the atmosphere, comparable to that of ultrahigh-energy cosmic

  17. The rapid atmospheric monitoring system of the Pierre Auger Observatory

    NARCIS (Netherlands)

    Abreu, P.; Aglietta, M.; Ahlers, M.; Ahn, E. J.; Albuquerque, I. F. M.; Allard, D.; Allekotte, I.; Allen, J.; Allison, P.; Almela, A.; Alvarez Castillo, J.; Alvarez-Muniz, J.; Alves Batista, R.; Ambrosio, M.; Aminaei, A.; Anchordoqui, L.; Andringa, S.; Antici'c, T.; Aramo, C.; Arganda, E.; Arqueros, F.; Asorey, H.; Assis, P.; Aublin, J.; Ave, M.; Avenier, M.; Avila, G.; Badescu, A. M.; Balzer, M.; Barber, K. B.; Barbosa, A. F.; Bardenet, R.; Barroso, S. L. C.; Baughman, B.; Baeuml, J.; Baus, C.; Beatty, J. J.; Becker, K. H.; Belletoile, A.; Bellido, J. A.; BenZvi, S.; Berat, C.; Bertou, X.; Biermann, P. L.; Billoir, P.; Blanco, F.; Blanco, M.; Bleve, C.; Bluemer, H.; Bohacova, M.; Boncioli, D.; Bonifazi, C.; Bonino, R.; Borodai, N.; Brack, J.; Brancus, I.; Brogueira, P.; Brown, W. C.; Bruijn, R.; Buchholz, P.; Bueno, A.; Buroker, L.; Burton, R. E.; Caballero-Mora, K. S.; Caccianiga, B.; Caramete, L.; Caruso, R.; Castellina, A.; Catalano, O.; Cataldi, G.; Cazon, L.; Cester, R.; Chauvin, J.; Cheng, S. H.; Chiavassa, A.; Chinellato, J. A.; Diaz, J. Chirinos; Chudoba, J.; Cilmo, M.; Clay, R. W.; Cocciolo, G.; Collica, L.; Coluccia, M. R.; Conceicao, R.; Contreras, F.; Cook, H.; Cooper, M. J.; Coppens, J.; Cordier, A.; Coutu, S.; Covault, C. E.; Creusot, A.; Criss, A.; Cronin, J.; Curutiu, A.; Dagoret-Campagne, S.; Dallier, R.; Daniel, B.; Dasso, S.; Daumiller, K.; Dawson, B. R.; de Almeida, R. M.; De Domenico, M.; De Donato, C.; de Jong, S. J.; De la Vega, G.; de Mello Junior, W. J. M.; de Mello Neto, J. R. T.; De Mitri, I.; de Souza, V.; de Vries, K. D.; del Peral, L.; del Rio, M.; Deligny, O.; Dembinski, H.; Dhital, N.; Di Giulio, C.; Diaz Castro, M. L.; Diep, P. N.; Diogo, F.; Dobrigkeit, C.; Docters, W.; D'Olivo, J. C.; Dong, P. N.; Dorofeev, A.; dos Anjos, J. C.; Dova, M. T.; D'Urso, D.; Dutan, I.; Ebr, J.; Engel, R.; Erdmann, M.; Escobar, C. O.; Espadanal, J.; Etchegoyen, A.; Luis, P. Facal San; Falcke, H.; Fang, K.; Farrar, G.; Fauth, A. C.; Fazzini, N.; Ferguson, A. P.; Fick, B.; Figueira, J. M.; Filevich, A.; Filipcic, A.; Fliescher, S.; Fracchiolla, C. E.; Fraenkel, E. D.; Fratu, O.; Froehlich, U.; Fuchs, B.; Gaior, R.; Gamarra, R. F.; Gambetta, S.; Garcia, B.; Garcia Roca, S. T.; Garcia-Gamez, D.; Garcia-Pinto, D.; Garilli, G.; Gascon Bravo, A.; Gemmeke, H.; Ghia, P. L.; Giller, M.; Gitto, J.; Glass, H.; Gold, M. S.; Golup, G.; Gomez Albarracin, F.; Gomez Berisso, M.; Gomez Vitale, P. F.; Goncalves, P.; Gonzalez, G.; Gookin, B.; Gorgi, A.; Gouffon, P.; Grashorn, E.; Grebe, S.; Griffith, N.; Grillo, A. F.; Guardincerri, Y.; Guarino, F.; Guedes, G. P.; Hansen, P.; Harari, D.; Harrison, T. A.; Harton, J. L.; Haungs, A.; Hebbeker, T.; Heck, D.; Herve, A. E.; Hojvat, C.; Hollon, N.; Holmes, V. C.; Homola, P.; Horandel, J. R.; Horvath, P.; Hrabovsky, M.; Huber, D.; Huege, T.; Insolia, A.; Ionita, F.; Italiano, A.; Jansen, S.; Jarne, C.; Jiraskova, S.; Josebachuili, M.; Kadija, K.; Kampert, K. H.; Karhan, P.; Kasper, P.; Katkov, I.; Kegl, B.; Keilhauer, B.; Keivani, A.; Kelley, J. L.; Kemp, E.; Kieckhafer, R. M.; Klages, H. O.; Kleifges, M.; Kleinfeller, J.; Knapp, J.; Koang, D-H.; Kotera, K.; Krohm, N.; Kroemer, O.; Kruppke-Hansen, D.; Kuempel, D.; Kulbartz, J. K.; Kunka, N.; La Rosa, G.; Lachaud, C.; LaHurd, D.; Latronico, L.; Lauer, R.; Lautridou, P.; Le Coz, S.; Leao, M. S. A. B.; Lebrun, D.; Lebrun, P.; Leigui de Oliveira, M. A.; Letessier-Selvon, A.; Lhenry-Yvon, I.; Link, K.; Lopez, R.; Lopez Agueera, A.; Louedec, K.; Lozano Bahilo, J.; Lu, L.; Lucero, A.; Ludwig, M.; Lyberis, H.; Maccarone, M. C.; Macolino, C.; Maldera, S.; Maller, J.; Mandat, D.; Mantsch, P.; Mariazzi, A. G.; Marin, J.; Marin, V.; Maris, I. C.; Marquez Falcon, H. R.; Marsella, G.; Martello, D.; Martinez, H.; Martinez Bravo, O.; Martraire, D.; Masias Meza, J. J.; Mathes, H. J.; Matthews, J.; Matthews, A. J.; Matthiae, G.; Maurel, D.; Maurizio, D.; Mazur, P. O.; Medina-Tanco, G.; Melissas, M.; Melo, D.; Menichetti, E.; Menshikov, A.; Mertsch, P.; Meurer, C.; Meyhandan, R.; Mi'canovi'c, S.; Micheletti, M. I.; Minaya, I. A.; Miramonti, L.; Molina-Bueno, L.; Mollerach, S.; Monasor, M.; Ragaigne, D. Monnier; Montanet, F.; Morales, B.; Morello, C.; Moreno, E.; Moreno, J. C.; Mostafa, M.; Moura, C. A.; Muller, M. A.; Mueller, G.; Muenchmeyer, M.; Mussa, R.; Navarra, G.; Navarro, J. L.; Navas, S.; Necesal, P.; Nellen, L.; Nelles, A.; Neuser, J.; Nhung, P. T.; Niechciol, M.; Niemietz, L.; Nierstenhoefer, N.; Nitz, D.; Nosek, D.; Nozka, L.; Oehlschlaeger, J.; Olinto, A.; Ortiz, M.; Pacheco, N.; Selmi-Dei, D. Pakk; Palatka, M.; Pallotta, J.; Palmieri, N.; Parente, G.; Parizot, E.; Parra, A.; Pastor, S.; Paul, T.; Pech, M.; Pekala, J.; Pelayo, R.; Pepe, I. M.; Perrone, L.; Pesce, R.; Petermann, E.; Petrera, S.; Petrolini, A.; Petrov, Y.; Pfendner, C.; Piegaia, R.; Pierog, T.; Pieroni, P.; Pimenta, M.; Pirronello, V.; Platino, M.; Plum, M.; Ponce, V. H.; Pontz, M.; Porcelli, A.; Privitera, P.; Prouza, M.; Quel, E. J.; Querchfeld, S.; Rautenberg, J.; Ravel, O.; Ravignani, D.; Revenu, B.; Ridky, J.; Riggi, S.; Risse, M.; Ristori, P.; Rivera, H.; Rizi, V.; Roberts, J.; Rodrigues de Carvalho, W.; Rodriguez, G.; Rodriguez Cabo, I.; Rodriguez Martino, J.; Rodriguez Rojo, J.; Rodriguez-Frias, M. D.; Ros, G.; Rosado, J.; Rossler, T.; Roth, M.; Rouille-d'Orfeuil, B.; Roulet, E.; Rovero, A. C.; Ruehle, C.; Saftoiu, A.; Salamida, F.; Salazar, H.; Greus, F. Salesa; Salina, G.; Sanchez, F.; Santo, C. E.; Santos, E.; Santos, E. M.; Sarazin, F.; Sarkar, B.; Sarkar, S.; Sato, R.; Scharf, N.; Scherini, V.; Schieler, H.; Schiffer, P.; Schmidt, A.; Scholten, O.; Schoorlemmer, H.; Schovancova, J.; Schovanek, P.; Schroeder, F.; Schulte, S.; Schuster, D.; Sciutto, S. J.; Scuderi, M.; Segreto, A.; Settimo, M.; Shadkam, A.; Shellard, R. C.; Sidelnik, I.; Sigl, G.; Silva Lopez, H. H.; Sima, O.; 'Smialkowski, A.; Smida, R.; Snow, G. R.; Sommers, P.; Sorokin, J.; Spinka, H.; Squartini, R.; Srivastava, Y. N.; Stanic, S.; Stapleton, J.; Stasielak, J.; Stephan, M.; Stutz, A.; Suarez, F.; Suomijaervi, T.; Supanitsky, A. D.; Susa, T.; Sutherland, M. S.; Swain, J.; Szadkowski, Z.; Szuba, M.; Tapia, A.; Tartare, M.; Tascau, O.; Tcaciuc, R.; Thao, N. T.; Thomas, D.; Tiffenberg, J.; Timmermans, C.; Tkaczyk, W.; Todero Peixoto, C. J.; Toma, G.; Tomankova, L.; Tome, B.; Tonachini, A.; Travnicek, P.; Tridapalli, D. B.; Tristram, G.; Trovato, E.; Tueros, M.; Ulrich, R.; Unger, M.; Urban, M.; Valdes Galicia, J. F.; Valino, I.; Valore, L.; Van Aar, G.; van den Berg, A. M.; van Vliet, A.; Varela, E.; Vargas Cardenas, B.; Vazquez, J. R.; Vazquez, R. A.; Veberic, D.; Verzi, V.; Vicha, J.; Videla, M.; Villasenor, L.; Wahlberg, H.; Wahrlich, P.; Wainberg, O.; Walz, D.; Watson, A. A.; Weber, M.; Weidenhaupt, K.; Weindl, A.; Werner, F.; Westerhoff, S.; Whelan, B. J.; Widom, A.; Wieczorek, G.; Wiencke, L.; Wilczynska, B.; Wilczynski, H.; Will, M.; Williams, C.; Winchen, T.; Wommer, M.; Wundheiler, B.; Yamamoto, T.; Yapici, T.; Younk, P.; Yuan, G.; Yushkov, A.; Zamorano Garcia, B.; Zas, E.; Zavrtanik, D.; Zavrtanik, M.; Zaw, I.; Zepeda, A.; Zhou, J.; Zhu, Y.; Zimbres Silva, M.; Ziolkowski, M.; Martin, L.

    The Pierre Auger Observatory is a facility built to detect air showers produced by cosmic rays above 10(17) eV. During clear nights with a low illuminated moon fraction, the UV fluorescence light produced by air showers is recorded by optical telescopes at the Observatory. To correct the

  18. Development of a Computer Program for the Design of Auger ...

    African Journals Online (AJOL)

    The screw or auger conveyor is an important conveyor in agricultural and food processing industries. The classical approach to its analysis and design involve the determination of the type and dimensions of the pitch, capacity, screw housing, clearance, length and diameter, shaft diameter, speed of revolution, filling factor, ...

  19. The Pierre Auger Observatory status and latest results

    Directory of Open Access Journals (Sweden)

    Berat Corinne

    2017-01-01

    Full Text Available The Pierre Auger Observatory, in Argentina, is the present flagship experiment studying ultrahigh-energy cosmic rays (UHECRs. Facing the challenge due to low cosmic-ray flux at the highest energies, the Observatory has been taking data for more than a decade, reaching an exposure of over 50 000 km2 sr yr. The combination of a large surface detector array and fluorescence telescopes provides a substantial improvement in energy calibration and extensive air shower measurements, resulting in data of unprecedented quality. Moreover, the installation of a denser subarray has allowed extending the sensitivity to lower energies. Altogether, this contributes to provide important information on key questions in the UHECR field in the energy range from 0.1 EeV up to 100 EeV. A review of main results from the Pierre Auger Observatory is presented with a particular focus on the energy spectrum measurements, the mass composition studies, the arrival directions analyses, the search for neutral cosmic messengers, and the investigation of high-energy hadronic interactions. Despite this large amount of valuable results, the understanding of the nature of UHECRs and of their origin remains an open science case that the Auger collaboration is planning to address with the AugerPrime project to upgrade the Observatory.

  20. High Voltage-Cylinder Sector Analyzer 300/15: a cylindrical sector analyzer for electron kinetic energies up to 15 keV.

    Science.gov (United States)

    Rubio-Zuazo, J; Escher, M; Merkel, M; Castro, G R

    2010-04-01

    We have developed an energy analyzer, High Voltage-Cylinder Sector Analyzer 300/15, for electron kinetic energies up to 15 keV. It is especially suited for hard x-ray photoelectron spectroscopy, but also for ultraviolet and soft x-ray photoelectron spectroscopy (ultraviolet photoemission spectroscopy, x-ray photoemission spectroscopy), Auger electron spectroscopy, and reflection high energy electron spectroscopy. The analyzer is based on a cylinder sector with 90 degrees deflection, 300 mm slit-to-slit distance, and a four-element pre-retarding lens system with 50 mm sample-to-lens distance. The result is a very compact design of the analyzer that is easily integrated into a multipurpose experiment with different techniques. A low noise/low drift electronics is capable of continuous energy scans from 0 to 15 keV using nonlinear lens curves. The first analyzer is allocated at the Spanish CRG SpLine beamline at the ESRF at an end station where simultaneous surface x-ray diffraction is possible. The analyzer is operated routinely since 2006 up to 15 keV electron kinetic energy, expanding the achievable electron kinetic energy range compared to other commercial analyzers. In this work we present a detailed description of the developed electron analyzer. The analyzer capabilities, in terms of energy resolution and transmission, are shown by using an electron gun, an ultraviolet-discharge lamp, and hard x-ray synchrotron radiation as excitation sources.

  1. Protein-nanoparticle interaction in bioconjugated silver nanoparticles: A transmission electron microscopy and surface enhanced Raman spectroscopy study

    Science.gov (United States)

    Reymond-Laruinaz, Sébastien; Saviot, Lucien; Potin, Valérie; Marco de Lucas, María del Carmen

    2016-12-01

    Understanding the mechanisms of interaction between proteins and noble metal nanoparticles (NPs) is crucial to extend the use of NPs in biological applications and nanomedicine. We report the synthesis of Ag-NPs:protein bioconjugates synthesized in total absence of citrates or other stabilizing agents in order to study the NP-protein interaction. Four common proteins (lysozyme, bovine serum albumin, cytochrome-C and hemoglobin) were used in this work. Transmission electron microscopy (TEM) and surface enhanced Raman spectroscopy (SERS) were mainly used to study these bioconjugated NPs. TEM images showed Ag NPs with sizes in the 5-40 nm range. The presence of a protein layer surrounding the Ag NPs was also observed by TEM. Moreover, the composition at different points of single bioconjugated NPs was probed by electron energy loss spectroscopy (EELS). The thickness of the protein layer varies in the 3-15 nm range and the Ag NPs are a few nanometers away. This allowed to obtain an enhancement of the Raman signal of the proteins in the analysis of water suspensions of bioconjugates. SERS results showed a broadening of the Raman bands of the proteins which we attribute to the contribution of different configurations of the proteins adsorbed on the Ag NPs surface. Moreover, the assignment of an intense and sharp peak in the low-frequency range to Ag-N vibrations points to the chemisorption of the proteins on the Ag-NPs surface.

  2. Spectral methods for study of the G-protein-coupled receptor rhodopsin: I. Vibrational and electronic spectroscopy

    Science.gov (United States)

    Struts, A. V.; Barmasov, A. V.; Brown, M. F.

    2015-05-01

    Here we review the application of modern spectral methods for the study of G-protein-coupled receptors (GPCRs) using rhodopsin as a prototype. Because X-ray analysis gives us immobile snapshots of protein conformations, it is imperative to apply spectroscopic methods for elucidating their function: vibrational (Raman, FTIR), electronic (UV-visible absorption, fluorescence) spectroscopies, and magnetic resonance (electron paramagnetic resonance, EPR), and nuclear magnetic resonance (NMR). In the first of the two companion articles, we discuss the application of optical spectroscopy for studying rhodopsin in a membrane environment. Information is obtained regarding the time-ordered sequence of events in rhodopsin activation. Isomerization of the chromophore and deprotonation of the retinal Schiff base leads to a structural change of the protein involving the motion of helices H5 and H6 in a pH-dependent process. Information is obtained that is unavailable from X-ray crystallography, which can be combined with spectroscopic studies to achieve a more complete understanding of GPCR function.

  3. An internal report: Electron Spectroscopy of the Oxidation and Aging of U and Pu

    Energy Technology Data Exchange (ETDEWEB)

    Tobin, J. G. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-04-27

    Uranium and Plutonium are highly reactive elements that undergo not only chemical reactions but also nuclear reactions. This can lead to possibly significant materials degradation, a matter of potentially great concern. Here, the issue of the electronic structure changes that occur with oxidation and radiological aging will be addressed, in a fairly empirical manner. In essence, the sensitivity of various electron spectroscopic techniques to oxidation and aging will be surveyed and discussed, including the apparent limitations. It will be found that 5d and 4d X-ray absorption and electron energy loss are essentially blind to the changes corresponding to oxidation and aging in U and Pu.

  4. Gate-Tunable Landau Level Filling and Spectroscopy in Coupled Massive and Massless Electron Systems.

    Science.gov (United States)

    Cheng, Bin; Wu, Yong; Wang, Peng; Pan, Cheng; Taniguchi, T; Watanabe, K; Bockrath, M

    2016-07-08

    We report transport studies on coupled massive and massless electron systems, realized using twisted monolayer-graphene-natural bilayer-graphene stacks. We incorporate the layers in a dual-gated transistor geometry enabling independently tuning their charge density and the perpendicular electric field. In a perpendicular magnetic field, we observe a distinct pattern of gate-tunable Landau level crossings. Screening and interlayer electron-electron interactions yield a nonlinear monolayer gate capacitance. Data analysis enables determination of the monolayer's Fermi velocity and the bilayer's effective mass. The mass obtained is larger than that expected for isolated bilayers, suggesting that the interlayer interactions renormalize the band structure.

  5. Studying substrate effects on localized surface plasmons in an individual silver nanoparticle using electron energy-loss spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Fujiyoshi, Yoshifumi; Nemoto, Takashi; Kurata, Hiroki, E-mail: kurata@eels.kuicr.kyoto-u.ac.jp

    2017-04-15

    In this study, electron energy-loss spectroscopy (EELS) in conjunction with scanning transmission electron microscopy (STEM) was used to investigate surface plasmons in a single silver nanoparticle (NP) on a magnesium oxide substrate, employing an incident electron trajectory parallel to the substrate surface. This parallel irradiation allowed a direct exploration of the substrate effects on localized surface plasmon (LSP) excitations as a function of the distance from the substrate. The presence of the substrate was found to lower the symmetry of the system, such that the resonance energies of LSPs were dependent on the polarization direction relative to the substrate surface. The resulting mode splitting could be detected by applying different electron trajectories, providing results similar to those previously obtained from optical studies using polarized light. However, the LSP maps obtained by STEM-EELS analysis show an asymmetric intensity distribution with the highest intensity at the top surface of the NP (that is, far from the substrate), a result that is not predicted by optical simulations. We show that modifications of the applied electric field by the substrate cause this asymmetric intensity distribution in the LSP maps.

  6. Band gap and defect states of MgO thin films investigated using reflection electron energy loss spectroscopy

    Directory of Open Access Journals (Sweden)

    Sung Heo

    2015-07-01

    Full Text Available The band gap and defect states of MgO thin films were investigated by using reflection electron energy loss spectroscopy (REELS and high-energy resolution REELS (HR-REELS. HR-REELS with a primary electron energy of 0.3 keV revealed that the surface F center (FS energy was located at approximately 4.2 eV above the valence band maximum (VBM and the surface band gap width (EgS was approximately 6.3 eV. The bulk F center (FB energy was located approximately 4.9 eV above the VBM and the bulk band gap width was about 7.8 eV, when measured by REELS with 3 keV primary electrons. From a first-principles calculation, we confirmed that the 4.2 eV and 4.9 eV peaks were FS and FB, induced by oxygen vacancies. We also experimentally demonstrated that the HR-REELS peak height increases with increasing number of oxygen vacancies. Finally, we calculated the secondary electron emission yields (γ for various noble gases. He and Ne were not influenced by the defect states owing to their higher ionization energies, but Ar, Kr, and Xe exhibited a stronger dependence on the defect states owing to their small ionization energies.

  7. Spectroscopy on magnetically confined plasmas using electron beam ion trap spectrometers

    National Research Council Canada - National Science Library

    Graf, A T; Brockington, S; Horton, R; Howard, S; Hwang, D; Beiersdorfer, P; Clementson, J; Hill, D; May, M; Mclean, H; Wood, R; Bitter, M; Terry, J; Rowan, W L; Lepson, J K; Delgado-Aparicio, L

    2008-01-01

    Multiple spectrometers originally designed for and used at the University of California Lawrence Livermore National Laboratory's electron beam ion trap have found use at various magnetically confined plasma facilities...

  8. Studies of Cosmic Ray Composition and Air Shower Structure with the Pierre Auger Observatory

    Energy Technology Data Exchange (ETDEWEB)

    Abraham, : J.; Abreu, P.; Aglietta, M.; Aguirre, C.; Ahn, E.J.; Allard, D.; Allekotte, I.; Allen, J.; Alvarez-Muniz, J.; Ambrosio, M.; Anchordoqui, L.

    2009-06-01

    These are presentations to be presented at the 31st International Cosmic Ray Conference, in Lodz, Poland during July 2009. It consists of the following presentations: (1) Measurement of the average depth of shower maximum and its fluctuations with the Pierre Auger Observatory; (2) Study of the nuclear mass composition of UHECR with the surface detectors of the Pierre Auger Observatory; (3) Comparison of data from the Pierre Auger Observatory with predictions from air shower simulations: testing models of hadronic interactions; (4) A Monte Carlo exploration of methods to determine the UHECR composition with the Pierre Auger Observatory; (5) The delay of the start-time measured with the Pierre Auger Observatory for inclined showers and a comparison of its variance with models; (6) UHE neutrino signatures in the surface detector of the Pierre Auger Observatory; and (7) The electromagnetic component of inclined air showers at the Pierre Auger Observatory.

  9. Observation of Electronic Excitation Transfer Through Light Harvesting Complex II Using Two-Dimensional Electronic-Vibrational Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Lewis, NHC; Gruenke, NL; Oliver, TAA; Ballottari, M; Bassi, R; Fleming, GR

    2016-10-05

    Light-harvesting complex II (LHCII) serves a central role in light harvesting for oxygenic photosynthesis and is arguably the most important photosynthetic antenna complex. In this article, we present two-dimensional electronic–vibrational (2DEV) spectra of LHCII isolated from spinach, demonstrating the possibility of using this technique to track the transfer of electronic excitation energy between specific pigments within the complex. We assign the spectral bands via comparison with the 2DEV spectra of the isolated chromophores, chlorophyll a and b, and present evidence that excitation energy between the pigments of the complex are observed in these spectra. Lastly, we analyze the essential components of the 2DEV spectra using singular value decomposition, which makes it possible to reveal the relaxation pathways within this complex.

  10. Electronic structure of R Sb (R =Y , Ce, Gd, Dy, Ho, Tm, Lu) studied by angle-resolved photoemission spectroscopy

    Science.gov (United States)

    Wu, Yun; Lee, Yongbin; Kong, Tai; Mou, Daixiang; Jiang, Rui; Huang, Lunan; Bud'ko, S. L.; Canfield, P. C.; Kaminski, Adam

    2017-07-01

    We use high-resolution angle-resolved photoemission spectroscopy (ARPES) and electronic structure calculations to study the electronic properties of rare-earth monoantimonides RSb (R = Y, Ce, Gd, Dy, Ho, Tm, Lu). The experimentally measured Fermi surface (FS) of RSb consists of at least two concentric hole pockets at the Γ point and two intersecting electron pockets at the X point. These data agree relatively well with the electronic structure calculations. Detailed photon energy dependence measurements using both synchrotron and laser ARPES systems indicate that there is at least one Fermi surface sheet with strong three-dimensionality centered at the Γ point. Due to the "lanthanide contraction", the unit cell of different rare-earth monoantimonides shrinks when changing the rare-earth ion from CeSb to LuSb. This results in the differences in the chemical potentials in these compounds, which are demonstrated by both ARPES measurements and electronic structure calculations. Interestingly, in CeSb, the intersecting electron pockets at the X point seem to be touching the valence bands, forming a fourfold-degenerate Dirac-like feature. On the other hand, the remaining rare-earth monoantimonides show significant gaps between the upper and lower bands at the X point. Furthermore, similar to the previously reported results of LaBi, a Dirac-like structure was observed at the Γ point in YSb, CeSb, and GdSb, compounds showing relatively high magnetoresistance. This Dirac-like structure may contribute to the unusually large magnetoresistance in these compounds.

  11. Mean values of the LMM Auger transition in a KLM model.

    Science.gov (United States)

    Malonda, A Grau; Carles, A Grau; Garcia, G

    2006-01-01

    The standardization of radionuclides decaying by electron capture can be carried out in LS counters by the CIEMAT/NIST method. The KLM model considers a simplified atomic rearrangement model in which all L- and M-subshells have been averaged. In this paper, instead of considering the 22 rearrangement pathways of the KLM model, we concentrate our analysis on the pathways corresponding to L-Auger electron transition. It is proved that the counting efficiency depends strongly on the energy E(LMM). Therefore, it is important to know the optimum value for E(LMM) and how to obtain it. To this end, the equations of the probabilities and the reduced energies for 3816 atomic rearrangement pathways have been derived. To average the equations, a computer program called MOYEN has been developed. The energy E(LMM) has been computed for 55Fe and 125I from different mean value definitions.

  12. Muon counting using silicon photomultipliers in the AMIGA detector of the Pierre Auger observatory

    Science.gov (United States)

    Aab, A.; Abreu, P.; Aglietta, M.; Ahn, E. J.; Samarai, I. Al; Albuquerque, I. F. M.; Allekotte, I.; Allison, P.; Almela, A.; Alvarez Castillo, J.; Alvarez-Muñiz, J.; Ambrosio, M.; Anastasi, G. A.; Anchordoqui, L.; Andrada, B.; Andringa, S.; Aramo, C.; Arqueros, F.; Arsene, N.; Asorey, H.; Assis, P.; Aublin, J.; Avila, G.; Badescu, A. M.; Balaceanu, A.; Baus, C.; Beatty, J. J.; Becker, K. H.; Bellido, J. A.; Berat, C.; Bertaina, M. E.; Bertou, X.; Biermann, P. L.; Billoir, P.; Biteau, J.; Blaess, S. G.; Blanco, A.; Blazek, J.; Bleve, C.; Boháčová, M.; Boncioli, D.; Bonifazi, C.; Borodai, N.; Botti, A. M.; Brack, J.; Brancus, I.; Bretz, T.; Bridgeman, A.; Briechle, F. L.; Buchholz, P.; Bueno, A.; Buitink, S.; Buscemi, M.; Caballero-Mora, K. S.; Caccianiga, B.; Caccianiga, L.; Cancio, A.; Canfora, F.; Caramete, L.; Caruso, R.; Castellina, A.; Cataldi, G.; Cazon, L.; Cester, R.; Chavez, A. G.; Chiavassa, A.; Chinellato, J. A.; Chudoba, J.; Clay, R. W.; Colalillo, R.; Coleman, A.; Collica, L.; Coluccia, M. R.; Conceição, R.; Contreras, F.; Cooper, M. J.; Coutu, S.; Covault, C. E.; Cronin, J.; Dallier, R.; D'Amico, S.; Daniel, B.; Dasso, S.; Daumiller, K.; Dawson, B. R.; de Almeida, R. M.; de Jong, S. J.; De Mauro, G.; de Mello Neto, J. R. T.; De Mitri, I.; de Oliveira, J.; de Souza, V.; Debatin, J.; del Peral, L.; Deligny, O.; Di Giulio, C.; Di Matteo, A.; Díaz Castro, M. L.; Diogo, F.; Dobrigkeit, C.; D'Olivo, J. C.; Dorofeev, A.; dos Anjos, R. C.; Dova, M. T.; Dundovic, A.; Ebr, J.; Engel, R.; Erdmann, M.; Erfani, M.; Escobar, C. O.; Espadanal, J.; Etchegoyen, A.; Falcke, H.; Fang, K.; Farrar, G.; Fauth, A. C.; Fazzini, N.; Fick, B.; Figueira, J. M.; Filevich, A.; Filipčič, A.; Fratu, O.; Freire, M. M.; Fujii, T.; Fuster, A.; García, B.; Garcia-Pinto, D.; Gaté, F.; Gemmeke, H.; Gherghel-Lascu, A.; Ghia, P. L.; Giaccari, U.; Giammarchi, M.; Giller, M.; Głas, D.; Glaser, C.; Glass, H.; Golup, G.; Gómez Berisso, M.; Gómez Vitale, P. F.; González, N.; Gookin, B.; Gordon, J.; Gorgi, A.; Gorham, P.; Gouffon, P.; Grillo, A. F.; Grubb, T. D.; Guarino, F.; Guedes, G. P.; Hampel, M. R.; Hansen, P.; Harari, D.; Harrison, T. A.; Harton, J. L.; Hasankiadeh, Q.; Haungs, A.; Hebbeker, T.; Heck, D.; Heimann, P.; Herve, A. E.; Hill, G. C.; Hojvat, C.; Holt, E.; Homola, P.; Hörandel, J. R.; Horvath, P.; Hrabovský, M.; Huege, T.; Hulsman, J.; Insolia, A.; Isar, P. G.; Jandt, I.; Jansen, S.; Johnsen, J. A.; Josebachuili, M.; Kääpä, A.; Kambeitz, O.; Kampert, K. H.; Kasper, P.; Katkov, I.; Keilhauer, B.; Kemp, E.; Kieckhafer, R. M.; Klages, H. O.; Kleifges, M.; Kleinfeller, J.; Krause, R.; Krohm, N.; Kuempel, D.; Kukec Mezek, G.; Kunka, N.; Kuotb Awad, A.; LaHurd, D.; Latronico, L.; Lauscher, M.; Lebrun, P.; Legumina, R.; Leigui de Oliveira, M. A.; Letessier-Selvon, A.; Lhenry-Yvon, I.; Link, K.; Lopes, L.; López, R.; López Casado, A.; Luce, Q.; Lucero, A.; Malacari, M.; Mallamaci, M.; Mandat, D.; Mantsch, P.; Mariazzi, A. G.; Mariş, I. C.; Marsella, G.; Martello, D.; Martinez, H.; Martínez Bravo, O.; Masías Meza, J. J.; Mathes, H. J.; Mathys, S.; Matthews, J.; Matthews, J. A. J.; Matthiae, G.; Mayotte, E.; Mazur, P. O.; Medina, C.; Medina-Tanco, G.; Melo, D.; Menshikov, A.; Messina, S.; Micheletti, M. I.; Middendorf, L.; Minaya, I. A.; Miramonti, L.; Mitrica, B.; Mockler, D.; Molina-Bueno, L.; Mollerach, S.; Montanet, F.; Morello, C.; Mostafá, M.; Müller, G.; Muller, M. A.; Müller, S.; Naranjo, I.; Navas, S.; Nellen, L.; Neuser, J.; Nguyen, P. H.; Niculescu-Oglinzanu, M.; Niechciol, M.; Niemietz, L.; Niggemann, T.; Nitz, D.; Nosek, D.; Novotny, V.; Nožka, H.; Núñez, L. A.; Ochilo, L.; Oikonomou, F.; Olinto, A.; Pakk Selmi-Dei, D.; Palatka, M.; Pallotta, J.; Papenbreer, P.; Parente, G.; Parra, A.; Paul, T.; Pech, M.; Pedreira, F.; Pȩkala, J.; Pelayo, R.; Peña-Rodriguez, J.; Pereira, L. A. S.; Perrone, L.; Peters, C.; Petrera, S.; Phuntsok, J.; Piegaia, R.; Pierog, T.; Pieroni, P.; Pimenta, M.; Pirronello, V.; Platino, M.; Plum, M.; Porowski, C.; Prado, R. R.; Privitera, P.; Prouza, M.; Quel, E. J.; Querchfeld, S.; Quinn, S.; Ramos-Pollant, R.; Rautenberg, J.; Ravignani, D.; Reinert, D.; Revenu, B.; Ridky, J.; Risse, M.; Ristori, P.; Rizi, V.; Rodrigues de Carvalho, W.; Rodriguez Fernandez, G.; Rodriguez Rojo, J.; Rodríguez-Frías, M. D.; Rogozin, D.; Rosado, J.; Roth, M.; Roulet, E.; Rovero, A. C.; Saffi, S. J.; Saftoiu, A.; Salazar, H.; Saleh, A.; Salesa Greus, F.; Salina, G.; Sanabria Gomez, J. D.; Sánchez, F.; Sanchez-Lucas, P.; Santos, E. M.; Santos, E.; Sarazin, F.; Sarkar, B.; Sarmento, R.; Sarmiento-Cano, C.; Sato, R.; Scarso, C.; Schauer, M.; Scherini, V.; Schieler, H.; Schmidt, D.; Scholten, O.; Schovánek, P.; Schröder, F. G.; Schulz, A.; Schulz, J.; Schumacher, J.; Sciutto, S. J.; Segreto, A.; Settimo, M.; Shadkam, A.; Shellard, R. C.; Sigl, G.; Silli, G.; Sima, O.; Śmiałkowski, A.; Šmída, R.; Snow, G. R.; Sommers, P.; Sonntag, S.; Sorokin, J.; Squartini, R.; Stanca, D.; Stanič, S.; Stasielak, J.; Strafella, F.; Suarez, F.; Suarez Durán, M.; Sudholz, T.; Suomijärvi, T.; Supanitsky, A. D.; Sutherland, M. S.; Swain, J.; Szadkowski, Z.; Taborda, O. A.; Tapia, A.; Tepe, A.; Theodoro, V. M.; Timmermans, C.; Todero Peixoto, C. J.; Tomankova, L.; Tomé, B.; Tonachini, A.; Torralba Elipe, G.; Torres Machado, D.; Torri, M.; Travnicek, P.; Trini, M.; Ulrich, R.; Unger, M.; Urban, M.; Valbuena-Delgado, A.; Valdés Galicia, J. F.; Valiño, I.; Valore, L.; van Aar, G.; van Bodegom, P.; van den Berg, A. M.; van Vliet, A.; Varela, E.; Vargas Cárdenas, B.; Varner, G.; Vázquez, J. R.; Vázquez, R. A.; Veberič, D.; Verzi, V.; Vicha, J.; Villaseñor, L.; Vorobiov, S.; Wahlberg, H.; Wainberg, O.; Walz, D.; Watson, A. A.; Weber, M.; Weindl, A.; Wiencke, L.; Wilczyński, H.; Winchen, T.; Wittkowski, D.; Wundheiler, B.; Wykes, S.; Yang, L.; Yelos, D.; Yushkov, A.; Zas, E.; Zavrtanik, D.; Zavrtanik, M.; Zepeda, A.; Zimmermann, B.; Ziolkowski, M.; Zong, Z.; Zuccarello, F.

    2017-03-01

    AMIGA (Auger Muons and Infill for the Ground Array) is an upgrade of the Pierre Auger Observatory designed to extend its energy range of detection and to directly measure the muon content of the cosmic ray primary particle showers. The array will be formed by an infill of surface water-Cherenkov detectors associated with buried scintillation counters employed for muon counting. Each counter is composed of three scintillation modules, with a 10 m2 detection area per module. In this paper, a new generation of detectors, replacing the current multi-pixel photomultiplier tube (PMT) with silicon photo sensors (aka. SiPMs), is proposed. The selection of the new device and its front-end electronics is explained. A method to calibrate the counting system that ensures the performance of the detector is detailed. This method has the advantage of being able to be carried out in a remote place such as the one where the detectors are deployed. High efficiency results, i.e. 98% efficiency for the highest tested overvoltage, combined with a low probability of accidental counting (~2%), show a promising performance for this new system.

  13. Photoelectron spectroscopy of hexachloroplatinate-nucleobase complexes: Nucleobase excited state decay observed via delayed electron emission

    Science.gov (United States)

    Sen, Ananya; Matthews, Edward M.; Hou, Gao-Lei; Wang, Xue-Bin; Dessent, Caroline E. H.

    2015-11-01

    We report low-temperature photoelectron spectra of isolated gas-phase complexes of the hexachloroplatinate dianion bound to the nucleobases uracil, thymine, cytosine, and adenine. The spectra display well-resolved, distinct peaks that are consistent with complexes where the hexachloroplatinate dianion is largely intact. Adiabatic electron detachment energies for the hexachloroplatinate-nucleobase complexes are measured as 2.26-2.36 eV. The magnitudes of the repulsive Coulomb barriers (RCBs) of the complexes are all ˜1.7 eV, values that are lower than the RCB of the uncomplexed PtCl62- dianion as a result of charge solvation by the nucleobases. In addition to the resolved spectral features, broad featureless bands indicative of delayed electron detachment are observed in the 193 nm photoelectron spectra of the four clusters. The 266 nm spectra of the PtCl62- ṡ thymine and PtCl62- ṡ adenine complexes also display very prominent delayed electron emission bands. These results mirror recent results on the related Pt(CN)42- ṡ nucleobase complexes [A. Sen et al., J. Phys. Chem. B 119, 11626 (2015)]. The observation of delayed electron emission bands in the PtCl62- ṡ nucleobase spectra obtained in this work, as for the previously studied Pt(CN)42- ṡ nucleobase complexes, is attributed to one-photon excitation of nucleobase-centred excited states that can effectively couple to the electron detachment continuum, producing strong electron detachment. Moreover, the selective, strong excitation of the delayed emission bands in the 266 nm spectra is linked to fundamental differences in the individual nucleobase photophysics at this excitation energy. This strongly supports our previous suggestion that the dianion within these clusters can be viewed as a "dynamic tag" which has the propensity to emit electrons when the attached nucleobase decays over a time scale long enough to allow autodetachment.

  14. The Electronic Structure of Carbon and its Allotropes as Determined by Soft X-Ray Emission Spectroscopy

    Science.gov (United States)

    Velasquez, Steven

    1993-01-01

    A study of the electronic structure of the stage I and stage II alkali graphite intercalation compounds using soft x-ray emission spectroscopy has been done. The pi band of the alkali graphite intercalation compounds is strongly affected by the intercalation process as witnessed by the apparent change in shape of the density of states in comparison to highly oriented pyrolytic graphite. From the change in shape, it is possible to determine the amount of charge transferred from the intercalant to the graphite. Our result of complete charge transfer is in disagreement with the results of Wiech and his co-workers. A thorough discussion of both methods of analysis is presented. A comparison of the observed density of states of synthetically grown diamond with natural diamond indicates that synthetic diamond is not the same as natural diamond. A brief discussion of various techniques for growing diamond is presented, as well as the construction of a chemical vapor deposition apparatus to grow diamond-like thin films along with soft x-ray emission and Raman spectroscopy measurements. We find that diamond can only be grown at low pressures if it is highly defective. This is in agreement with theoretical models of chemical vapor deposition. We also discuss the electronic structure of a very rare form of diamond, Lonsdaleite (hexagonal diamond). Lonsdaleite is sp^3 bonded carbon but in a hexagonal matrix. It is only found in highly shocked systems and appears to be the metastable phase between graphite and diamond on the carbon phase diagram. We also briefly discuss the most recently discovered member of the carbon family, Buckminsterfullerene. We present electronic structure data on C_ {60} samples produced in a carbon-arc generator designed and built at the University. Comparison of our data to other published data shows very good agreement.

  15. Kissing G domains of MnmE monitored by X-ray crystallography and pulse electron paramagnetic resonance spectroscopy.

    Directory of Open Access Journals (Sweden)

    Simon Meyer

    2009-10-01

    Full Text Available MnmE, which is involved in the modification of the wobble position of certain tRNAs, belongs to the expanding class of G proteins activated by nucleotide-dependent dimerization (GADs. Previous models suggested the protein to be a multidomain protein whose G domains contact each other in a nucleotide dependent manner. Here we employ a combined approach of X-ray crystallography and pulse electron paramagnetic resonance (EPR spectroscopy to show that large domain movements are coupled to the G protein cycle of MnmE. The X-ray structures show MnmE to be a constitutive homodimer where the highly mobile G domains face each other in various orientations but are not in close contact as suggested by the GDP-AlF(x structure of the isolated domains. Distance measurements by pulse double electron-electron resonance (DEER spectroscopy show that the G domains adopt an open conformation in the nucleotide free/GDP-bound and an open/closed two-state equilibrium in the GTP-bound state, with maximal distance variations of 18 A. With GDP and AlF(x, which mimic the transition state of the phosphoryl transfer reaction, only the closed conformation is observed. Dimerization of the active sites with GDP-AlF(x requires the presence of specific monovalent cations, thus reflecting the requirements for the GTPase reaction of MnmE. Our results directly demonstrate the nature of the conformational changes MnmE was previously suggested to undergo during its GTPase cycle. They show the nucleotide-dependent dynamic movements of the G domains around two swivel positions relative to the rest of the protein, and they are of crucial importance for understanding the mechanistic principles of this GAD.

  16. Electronic structure of interstitial hydrogen in lutetium oxide from DFT+U calculations and comparison study with μ SR spectroscopy

    Science.gov (United States)

    da Silva, E. Lora; Marinopoulos, A. G.; Vieira, R. B. L.; Vilão, R. C.; Alberto, H. V.; Gil, J. M.; Lichti, R. L.; Mengyan, P. W.; Baker, B. B.

    2016-07-01

    The electronic structure of hydrogen impurity in Lu2O3 was studied by first-principles calculations and muonium spectroscopy. The computational scheme was based on two methods which are well suited to treat defect calculations in f -electron systems: first, a semilocal functional of conventional density-functional theory (DFT) and secondly a DFT+U approach which accounts for the on-site correlation of the 4 f electrons via an effective Hubbard-type interaction. Three different types of stable configurations were found for hydrogen depending upon its charge state. In its negatively charged and neutral states, hydrogen favors interstitial configurations residing either at the unoccupied sites of the oxygen sublattice or at the empty cube centers surrounded by the lanthanide ions. In contrast, the positively charged state stabilized only as a bond configuration, where hydrogen binds to oxygen ions. Overall, the results between the two methods agree in the ordering of the formation energies of the different impurity configurations, though within DFT+U the charge-transition (electrical) levels are found at Fermi-level positions with higher energies. Both methods predict that hydrogen is an amphoteric defect in Lu2O3 if the lowest-energy configurations are used to obtain the charge-transition, thermodynamic levels. The calculations of hyperfine constants for the neutral interstitial configurations show a predominantly isotropic hyperfine interaction with two distinct values of 926 MHz and 1061 MHz for the Fermi-contact term originating from the two corresponding interstitial positions of hydrogen in the lattice. These high values are consistent with the muonium spectroscopy measurements which also reveal a strongly isotropic hyperfine signature for the neutral muonium fraction with a magnitude slightly larger (1130 MHz) from the ab initio results (after scaling with the magnetic moments of the respective nuclei).

  17. Ozone absorption spectroscopy in search of low-lying electronic states

    Science.gov (United States)

    Anderson, S. M.; Mauersberger, K.

    1995-01-01

    A spectrometer capable of detecting ozone absorption features 9 orders of magnitude weaker than the Hartley band has been employed to investigate the molecule's near-infrared absorption spectrum. At this sensitivity a wealth of information on the low-lying electronically excited states often believed to play a role in atmospheric chemistry is available in the form of vibrational and rotational structure. We have analyzed these spectra using a combination of digital filtering and isotope substitution and find evidence for three electronically excited states below 1.5 eV. The lowest of these states is metastable, bound by approximately 0.1 eV and probably the (3)A2 rather than the (3)B2 state. Its adiabatic electronic energy is 1.24 +/- 0.01 eV, slightly above the dissociation energy of the ground state. Two higher states, at 1.29 +/- 0.03 and 1.48 +/- 0.03 eV are identified as the (3)B2 and the (