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Sample records for auger electron spectroscopy

  1. Auger electron spectroscopy of alloys

    International Nuclear Information System (INIS)

    This thesis describes how the surface compositions of some alloys can be determined by Auger Electron Spectroscopy (AES). The motivation for this research and the reasons for the choice of alloy systems studied are formulated. The theoretical background of AES is briefly discussed and the apparatus used and the experimental procedures applied are described. Four alloy systems have been investigated in this thesis - Ni-Cu and Pd - Ag (consisting of a component active in most cataytic reactions - Ni and Pd; and a component which is almost inactive for a number of reactions - Cu and Ag) and Pt - Pd and Pt-Ir (consisting of two active components). Knowledge of the surface composition of the various alloy systems is shown to be essential for the interpretation of catalytic results. (Auth./C.F.)

  2. 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)

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

    International Nuclear Information System (INIS)

    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 MnF2 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

  4. Defect identification by compositional defect review using auger electron spectroscopy

    International Nuclear Information System (INIS)

    Defect identification plays an enabling role in determining the source of particles that occur during semiconductor processing and are subsequently detected by defect inspection tools. Auger electron spectroscopy provides a high spatial resolution, surface sensitive analytical probe that is well matched to examining small, thin or complex defects. A focused ion beam (FIB) can be used to cross-section buried defects and structures for subsequent Auger analysis. Such measurements have been made on defects from two wafers pulled at different process steps. One wafer was analyzed after poly-Si deposition, and the other wafer was analyzed after metal 2 etch. The defects on the poly-Si wafer are Si particles. Three types of particles were found on the metal 2 wafer: C-based, stainless steel, and Si-oxide. The majority of defects on this wafer are C-based. Auger, EDS and FIB results will be compared for representative defects on these two wafers

  5. Coincidence Auger spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Penent, F. [LCPMR, Universite Pierre et Marie Curie, 75231 Paris 5 (France) and DIAM, Universite Pierre et Marie Curie, 75252 Paris 5 (France)]. E-mail: penent@ccr.jussieu.fr; Lablanquie, P. [LURE, Universite Paris Sud, 91898 Orsay (France); Hall, R.I. [DIAM, Universite Pierre et Marie Curie, 75252 Paris 5 (France); Palaudoux, J. [LCPMR, Universite Pierre et Marie Curie, 75231 Paris 5 (France); Ito, K. [Photon Factory, IMSS, KEK, Tsukuba 305-0801 (Japan); Hikosaka, Y. [Photon Factory, IMSS, KEK, Tsukuba 305-0801 (Japan); IMS, Okazaki 444-8585 (Japan); Aoto, T. [Photon Factory, IMSS, KEK, Tsukuba 305-0801 (Japan); Eland, J.H.D. [Physical and Theoretical Chemistry Laboratory, South Parks Road, Oxford OX1 3DW (United Kingdom)

    2005-06-15

    Auger electron spectroscopy (AES) and photoelectron spectroscopy (PES) are (with X-ray emission spectroscopy, XES) powerful analytical tools for material science and gas phase studies. However, the interpretation of Auger spectra can be very difficult due to the number and complexity of the involved processes. A deeper analysis, that allows a better understanding of relaxation processes following inner shell ionization, is possible with coincidence Auger spectroscopy. This method gives a new insight into electron correlation and allows disentangling of complex Auger electron spectra. In this paper, we present some examples related to gas phase coincidence Auger electron spectroscopy using synchrotron radiation. The detection in coincidence of an Auger electron with a threshold photoelectron presents two main advantages which are good energy resolution and high coincidence count rates. This technique has also provided new results on double Auger decay processes. A further qualitative breakthrough has been made with the development of a new experimental set-up based on a magnetic bottle time-of-flight electron spectrometer. This opens up the field of multi-electron coincidence spectroscopy and allows a most detailed analysis with characterization of all possible decay pathways following inner shell ionization.

  6. Monte-Carlo simulation of backscattered electrons in Auger electron spectroscopy. Part 1: Backscattering factor calculation

    Energy Technology Data Exchange (ETDEWEB)

    Tholomier, M.; Vicario, E.; Doghmane, N.

    1987-10-01

    The contribution of backscattered electrons to Auger electrons yield was studied with a multiple scattering Monte-Carlo simulation. The Auger backscattering factor has been calculated in the 5 keV-60 keV energy range. The dependence of the Auger backscattering factor on the primary energy and the beam incidence angle were determined. Spatial distributions of backscattered electrons and Auger electrons are presented for a point incident beam. Correlations between these distributions are briefly investigated.

  7. Auger electron spectroscopy as a tool for measuring intramolecular charges of adsorbed molecules

    Science.gov (United States)

    Magkoev, T. T.

    1993-10-01

    A way for the determination of the values of intramolecular charges of adsorbed molecules of some binary dielectrics, based on Auger electron spectroscopy (AES), is proposed. These values can be obtained from the coverage dependences of the ratios of intensities of anion KL 23L 23 and KL 1L 1 Auger transitions, which are sensitive to the amount of charge at the 2p-orbitals. As an example, MgO adsorbed on Mo(110) is presented.

  8. Application of Auger electron spectroscopy in studies about diffusion of Cu in thin Ni films

    International Nuclear Information System (INIS)

    The diffusion coefficient of Cu in thin Ni films (350A) at low temperatures is determined by using Auger electron spectroscopy and timepermeation technic. A grain-boundary mechanism is proposed for the diffusion of Cu in Ni. The activation energy is determined to Q=0,6eV. (Author)

  9. Auger spectroscopy and surface analysis

    International Nuclear Information System (INIS)

    In 1925 Pierre Auger reported on his observations of low energy electrons associated with core-ionised atoms in cloud chamber experiments. He was able to correctly identify the mechanism for their production, and such electrons are now known as Auger electrons. Typically Auger electrons have energies in the range 10 eV to 2 keV. The short distance that such low energy electrons travel in solids ensures that Auger electrons come from the surface layers. The data generated by the AES technique are complex. There are at least three electrons involved in the process, and there are many possible configurations for the atom. These possibilities led to spectra that are not readily interpreted in detail. Theory lags behind experiment in this area. In principle, it should be possible to find information about the chemical environment of atoms from Auger spectra. While there are clear changes in spectral lineshapes, there is no simple way to go from the spectra to an understanding of the chemical bonding of the atom. There are a number of experiments currently underway which aim to improve our understanding of the Auger process. Synchrotron experiments with tunable energy x-rays are providing new insight. Experiments that use positrons to excite Auger emission have also produced further recent understanding. Coincidence experiments between photoelectrons and Auger electrons have also made recent advances. Auger photoelectron coincidence spectroscopy reduces the complexity of Auger spectra by only counting those electrons that occur as a consequence of selected ionizations. The effect is to reduce the complexity of the spectra, and to isolate processes that are often clouded by the simultaneous occurrence of other effects. (author)

  10. Atomic and molecular photoelectron and Auger-electron-spectroscopy studies using synchrotron radiation

    International Nuclear Information System (INIS)

    Electron spectroscopy, combined with synchrotron radiation, was used to measure the angular distributions of photoelectrons and Auger electrons from atoms and molecules as functions of photon energy. The branching ratios and partial cross sections were also measured in certain cases. By comparison with theoretical calculations, the experimental results are interpreted in terms of the characteristic electronic structure and ionization dynamics of the atomic or molecular sample. The time structure of the synchrotron radiation source was used to record time-of-flight (TOF) spectra of the ejected electrons. The double-angle-TOF method for the measurement of photoelectron angular distributions is discussed. This technique offers the advantages of increased electron collection efficiency and the elimination of certain systematic errors. An electron spectroscopy study of inner-shell photoexcitation and ionization of Xe, photoelectron angular distributions from H2 and D2, and photoionization cross sections and photoelectron asymmetries of the valence orbitals of NO are reported

  11. Quantum-beat Auger spectroscopy

    CERN Document Server

    Zhang, Song Bin

    2015-01-01

    The concept of nonlinear quantum-beat pump-probe Auger spectroscopy is introduced by discussing a relatively simple four-level model system. We consider a coherent wave packet involving two low-lying states that was prepared by an appropriate pump pulse. This wave packet is subsequently probed by a weak, time-delayed probe pulse with nearly resonant coupling to a core-excited state of the atomic or molecular system. The resonant Auger spectra are then studied as a function of the duration of the probe pulse and the time delay. With a bandwidth of the probe pulse approaching the energy spread of the wave packet, the Auger yields and spectra show quantum beats as a function of pump-probe delay. An analytic theory for the quantum-beat Auger spectroscopy will be presented, which allows for the reconstruction of the wave packet by analyzing the delaydependent Auger spectra. The possibility of extending this method to a more complex manifold of electronic and vibrational energy levels is also discussed.

  12. Scanning Auger electron spectroscopy studies of grain-boundary segregation in Type 304 stainless steel

    International Nuclear Information System (INIS)

    Scanning Auger electron spectroscopy studies have been conducted on grain-boundary surfaces of Type 304 stainless steel that were fractured in situ. To enhance the probability of intergranular fracture, the specimens were first subjected to creep deformation for 1000 h at 7000C. A semiquantitative surface chemical composition was calculated from the peak heights of Auger electron spectra. The concentration of Cr at the fracture surface was not different from the bulk value. This indicates that the long-term heat treatment caused healing of the sensitization. The concentrations of S, C, and Si at the fracture surface were at least an order of magnitude higher than the bulk values. Chemical composition profiles obtained by ion-sputtering indicated that segregation of S, C, P, and Si occurred within a depth of several atomic monolayers from the grain-boundary surface. Mo, Mn and Cu were not detected. The concentrations of Ni and Fe are in good agreement with the bulk chemical analysis

  13. 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...

  14. Sputtering measurements on controlled thermonuclear reactor materials using Auger electron spectroscopy

    International Nuclear Information System (INIS)

    Simultaneous auger electron spectroscopy and ion sputtering have been used to measure the sputter yield, S (atom/ion), for Ar+ on carbon, tungsten, niobium, and silver in the energy range from 0.5 to 1.5 keV and for H+ on tungsten, carbon, and silver at 11 keV. All measurements were performed on thin films, ranging in thickness from 150 to 6000 A, which were maintained at room temperature during bombardment. These films were produced by vacuum vapor deposition, and the thicknesses were measured by surface profilometry. The auger electron signals were used to determine the time required to etch through a film; from these measurements and a knowledge of the ion current density, the sputter yield was determined. For Ar+, 0.7 less than or equal to S less than or equal to 5.1 and for H+, 0.004 less than or equal to S less than or equal to 0.04 for the various materials studied in this energy range. Agreement with earlier experimental results is generally within +-25 percent

  15. Atomic and Molecular Photoelectron and Auger Electron SpectroscopyStudies Using Synchrotron Radiation

    Energy Technology Data Exchange (ETDEWEB)

    Southworth, Stephen H.

    1982-01-01

    Electron spectroscopy, combined with synchrotron radiation, was used to measure the angular distributions of photoelectrons and Auger electrons from atoms and molecules as functions of photon energy. The branching ratios and partial cross sections were a 130 measured in certain cases. By comparison with theoretical calculations, the experimental results are interpreted in terms of the characteristic electronic structure and ionization dynamics of the atomic or molecular sample. The time structure of the synchrotron radiation source was used to record time-of-flight (TOF) spectra o f the ejected electrons. The ''a double-angle-TOF'' method for the measurement of photoelectron angular distributions is discussed. This technique offers the advantages of increased electron collect ion efficiency and the elimination of certain systematic errors. Several results were obtained for Xe using photon energies in the range hv {approx_equal} 60-190 eV, where excitation and ionization of the inner-subshell 4d electrons dominates. The 4d asymmetry parameter {beta} exhibits strong oscillations with energy, in agreement with several theoretical calculations. As predicted, the 5p asymmetry parameter was observed to deviate strongly from that calculated using the independent-electron model, due to intershell correlation with the 4d electrons.

  16. Secondary electron yield and Auger electron spectroscopy measurements on oxides, carbide, and nitride of niobium

    International Nuclear Information System (INIS)

    Secondary electron yield measurements before and after Ar ion sputtercleaning were made on Nb and Nb compounds of interest for rf superconductingcavities. Total secondary electron yields (sigma) for primary energies 20--1500 eV were measured for solid Nb (sigma/sub max/ = 1.3 at 300 eV), anodized Nb2O5 (sigma/sub max/ = 1.2 at 300 eV), and powders of Nb(sigma/sub max/ = 1.0 at 400 eV), NbO (sigma/sub max/ = 0.9 at 400 eV), NbO2 (sigma/sub max/ = 1.0 at 400 eV), Nb2O5 (sigma/sub max/ = 0.95 at 400 eV), NbC(sigma/sub max/ = 0.8 at 400 eV), and NbN (sigma/sub max/ = 0.8 at 500 eV). Determinations were made for Auger elemental sensitivities, and the relationship between Auger peak heights and oxide stoichiometry is discussed. The sputter etch rate of anodized Nb2O5 was measured by depth profiling anodic coatings of known thickness

  17. Quantitative auger electron spectroscopy of the interface carbon layer formation on the vacuum cleavage surfaces of layered semiconductor In4Se3 crystals

    International Nuclear Information System (INIS)

    The results of the qualitative Auger electron spectroscopy of the interface carbon layer formation on the high vacuum cleavage surfaces of layered semiconductor In4Se3 crystals are presented. The kinetics of interfacial carbon layer formation on the cleavage surfaces of crystals and the elemental and phase composition of the interface dependent on the exposition time in high vacuum and on the dose of electron irradiation have been studied by the quantitative Auger electron and mass-spectroscopy methods

  18. Investigation of grain boundary chemistry in Al-Li 2195 welds using Auger electron spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Sanders, J.H. [National Aeronautics and Space Administration, Huntsville, AL (United States). George C. Marshall Space Flight Center

    1996-05-01

    Al-Li alloy 2195 is a low-density material with high fracture toughness that is particularly well-suited for aerospace systems. It will replace Al-Cu alloy 2219 in the Super Light Weight Tank (SLWT), a modified version of the external tank being developed for the Space Shuttle to support Space Station deployment. Recent efforts have focused on joining 2195 with variable polarity plasma arc welding, as well as repairing 2195 welds with tungsten inert gas techniques. During this study, Auger electron spectroscopy (AES) was used to examine grain boundary chemistry in 2195 welds. Results indicated that weld integrity depends on whether (and how much) the grain boundaries are covered with thin films comprised of a mixture of discontinuous Al{sub 2}O{sub 3} in Al (Al/Al{sub 2}O{sub 3}), which form during weld solidification. O was probably introduced as a contaminant in the shielding gases, occurring at low levels considered negligible for Al alloys that do not contain Li. However, oxidation kinetics in 2195 are increased by Li enrichment of small quantities of Al{sub 2}O{sub 3}, further enhancing thin film formation at the grain boundaries. Al{sub 2}O{sub 3} can ultimately occupy sufficient grain boundary area to degrade the material`s mechanical properties, producing negative effects that are compounded by the cumulative heat input of multi-pass repair welding. (orig.)

  19. Auger electron spectroscopy in sputtering measurements: Application to low-energy Ar+ sputtering of Ag and Nb

    International Nuclear Information System (INIS)

    The sputtering of Ag and Nb by Ar+ in the energy range from 0.5 to 1.5 keV has been measured. The agreement with extant data, where available, is good. The experimental technique is a new adaptation of certain earlier methods and employs Auger electron spectroscopy of a continuously sputtered area of a thin-film composite structure, produced by vapor deposition. This new method should permit very low sputter yields (Sapproximately-less-than10-3) to be measured in subsequent experiments

  20. Electronic many-body effects at metal-organic interfaces studied with PES, NEXAFS and resonant Auger Raman spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Haeming, M.; Schoell, A.; Reinert, F. [Universitaet Wuerzburg, Experimentelle Physik VII, D-97074 Wuerzburg (Germany); Umbach, E. [Karlsruhe Institut fuer Technologie (KIT) D-76021 Karlsruhe (Germany)

    2011-07-01

    Electronic many-body and correlation effects have been studied intensively at transition metal compounds with localized d/f electrons. They are related to interesting material properties, e.g. Mott metal-insulator transitions, charge transfer satellites and superconductivity. Recent investigations of graphene,{sup 1} C{sub 60},{sup 2} and TTF-TCNQ{sup 3} showed that many-body effects can also be important for organic thin films. We have investigated several organic thin films (PTCDA, PTCDI, BTCDA, BTCDI, SnPc) deposited on a Ag(111) surfaces with photoelectron spectroscopy, NEXAFS and resonant Auger Raman spectroscopy. Our data provide significant indications for electronic many-body effects involving substrate-adsorbate charge transfer, which can be understood by concepts developed for charge transfer compounds. These results give insight into new, interesting aspects of physics at metal-organic interfaces. {sup 1} I.

  1. Channel-resolved photo- and Auger-electron spectroscopy of halogenated hydrocarbons

    Science.gov (United States)

    Ablikim, Utuq; Kaderiya, B.; Kumarapan, V.; Kushawaha, R.; Rudenko, A.; Rolles, D.; Xiong, H.; Berrah, N.; Bomme, C.; Savelyev, E.; Kilcoyne, D.

    2016-05-01

    Inner-shell photoelectron and Auger electron spectra of polyatomic molecules such as halogenated hydrocarbons are typically hard to interpret and assign due to many overlapping states that form broad bands even in high-resolution measurements. With the help of electron-ion-ion coincidence measurements performed using the velocity map imaging technique, we are able to detect high-energy (assigning individual components of the electron spectra to specific potential surfaces and final states. In this work, we present measurements on CH3 I, CH2 IBr, and CH2 ICl molecules in the gas-phase using soft x-ray light provided by the Advanced Light Source at LBNL. This project is supported by the DOE, Office of Science, BES, Division of Chemical, Geological and Biological Sciences under Award Number DE-FG02-86ER13491 (U.A., B.K., V.K., A.R., D.R.) and Award Number DE-SC0012376 (H.X., N.B.).

  2. Characterisation of the surface over-layer of welded uranium by FIB, SIMS and Auger electron spectroscopy

    International Nuclear Information System (INIS)

    Secondary ion mass spectrometry (SIMS), focused ion beam (FIB) milling and Auger electron spectroscopy have been used to examine the composition and surface structure of uranium welded by an electron beam. Four characteristic areas of the metal surface were designated, these being: body (unaffected by the welding process), heat affected zone (HAZ), weld edge and weld. Surface composition to a depth of a few microns was determined using SIMS profiling, and direct thickness measurements of surface over-layers on the metal were made using FIB. Marked variations in both the thickness and composition of the over-layers were found when comparing the body/HAZ, weld edge and weld material. Additionally, numerous prismatic inclusions, approximately 5 μm2, were observed at the surface of the weld material. Auger and SIMS analyses indicated these inclusions were nitro-carbides. An increased concentration of these inclusions and other elemental impurities at the margins of the weld and within the HAZ indicated that during welding a segregation of impurities from the molten metal had occurred. The results are discussed in terms of processes considered to be occurring during welding and their implications in regard to corrosion in hydrogen atmospheres.

  3. Auger electron appearance potential spectrum of Ni

    International Nuclear Information System (INIS)

    Electrons are accelerated onto a solid polycrystalline Ni surface. These primary electrons interact with the surface to produce one of two phenomena: x-ray fluorescence, or Auger electron emission. Auger Electron Appearance Potential Spectroscopy (AEAPS) is a process by which the Auger component of the secondary electron flux is analysed to extract qualitative information about the electronic structure of the empty conduction band states. In AEAPS, the threshold behavior of the Auger transitions is examined by taking the first derivative of the secondary electron current with respect to the incident electron energy using the potential modulation technique. Width of the empty band, degree of localization of the conduction band wave functions, overlapping of the 3d band with the 4s, and satellite phenomena are among the important parameters ascertainable by AEAPS. The present AEAPS measurements of L3 levels of Ni are compared with the reported data from Soft X-ray Appear nce Potential Spectroscopy (SXAPS) of Ni. SXAPS is a complimentary process of AEAPS in that it examines the secondary xray fluorescence from the surface in much the same way as AEAPS examines the total electron yield. AEAPS, used alone, or in conjunction with SXAPS, is considered to be a powerful technique for the systematic investgation of series of metals, such as the transition, or lanthanide series

  4. Silicidation in Ni/Si thin film system investigated by X-ray diffraction and Auger electron spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Abhaya, S. [Materials Science Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102 (India); Amarendra, G. [Materials Science Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102 (India)]. E-mail: amar@igcar.gov.in; Kalavathi, S. [Materials Science Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102 (India); Gopalan, Padma [Materials Science Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102 (India); Kamruddin, M. [Materials Science Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102 (India); Tyagi, A.K. [Materials Science Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102 (India); Sastry, V.S. [Materials Science Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102 (India); Sundar, C.S. [Materials Science Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102 (India)

    2007-02-15

    Silicide formation induced by thermal annealing in Ni/Si thin film system has been investigated using glancing incidence X-ray diffraction (GIXRD) and Auger electron spectroscopy (AES). Silicide formation takes place at 870 K with Ni{sub 2}Si, NiSi and NiSi{sub 2} phases co-existing with Ni. Complete conversion of intermediate silicide phases to the final NiSi{sub 2} phase takes place at 1170 K. Atomic force microscopy measurements have revealed the coalescence of pillar-like structures to ridge-like structures upon silicidation. A comparison of the experimental results in terms of the evolution of various silicide phases is presented.

  5. ANALYSIS OF PASSIVATED SURFACES FOR MASS SPECTROMETER INLET SYSTEMS BY AUGER ELECTRON AND X-RAY PHOTOELECTRON SPECTROSCOPY

    Energy Technology Data Exchange (ETDEWEB)

    Ajo, H.; Clark, E.

    2010-09-01

    Stainless steel coupons approximately 0.5' in diameter and 0.125' thick were passivated with five different surface treatments and an untreated coupon was left as a control. These surface treatments are being explored for use in tritium storage containers. These coupons were made to allow surface analysis of the surface treatments using well-know surface analysis techniques. Depth profiles using Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS) were performed on these coupons to characterize the surface and near surface regions. Scanning electron microscope (SEM) images were collected as well. All of the surface treatments studied here appear to change the surface morphology dramatically, as evidenced by lack of tool marks on the treated samples. In terms of the passivation treatment, Vendors A-D appeared to have oxide layers that were very similar in thickness to each other (0.7-0.9 nm thick) as well as the untreated samples (the untreated sample oxide layers appeared to be somewhat larger). Vendor E's silicon coating appears to be on the order of 200 nm thick.

  6. Effect of heating on the behaviors of hydrogen in C-TiC films with auger electron spectroscopy and secondary ion mass spectroscopy analyses

    International Nuclear Information System (INIS)

    C-TiC films with a content of 75% TiC were prepared with magnetron sputtering deposition followed by Ar+ ion bombardment. Effect of heating on the behaviors of hydrogen in C-TiC films before and after heating was studied with Auger Electron Spectroscopy and Secondary Ion Mass Spectroscopy (SIMS) analyses. SIMS depth profiles of hydrogen after H+ ion implantation and thermal treatment show different hydrogen concentrations in C-TiC coatings and stainless steel. SIMS measurements show the existence of TiH, TiH2, CH3, CH4, C2H2 bonds in the films after H+ ion irradiation and the changes in the Ti LMM, Ti LMV and C KLL Auger line shape reveal that they have a good hydrogen retention ability after heating up to the temperature 393 K. All the results show that C-TiC coatings can be used as a hydrogen retainer or hydrogen permeable barrier on stainless steel to protect it from hydrogen brittleness

  7. A detailed Auger electron spectroscopy study of the first stages of the growth of C60 thin films

    Science.gov (United States)

    Vidal, R. A.; Ferrón, J.

    2015-11-01

    In this work we take advantage of the large sensitivity and in-depth resolution of Auger electron spectroscopy (AES) to study in a detailed way the growth of C60 over different substrates, namely Cu(1 1 1), Si(1 0 0) and graphene. The ability of AES, as compared to more local probes like STM or AFM, to follow the process in a dynamic way, allows us to study the growth of C60 below and over one ML, including the change of C60 over either Si or Cu to the growth of C60 over a C60 film. We found that the growth always proceeds layer by layer. This result shows that differences in diffusion barriers are not as important as one may think following the idea of diffusion by a jumping mechanism. We propose that the sticking coefficient, governed by the adsorption energy, is responsible for the differences observed between Cu and Si. Our results also point to a different charge transfer among fullerene molecules and these surfaces. The same result is suggested in the case of C60 over graphene, but in this case our conclusion comes from the variable temperature experiments.

  8. Investigation of Sn surface segregation during GeSn epitaxial growth by Auger electron spectroscopy and energy dispersive x-ray spectroscopy

    International Nuclear Information System (INIS)

    The mechanism of Sn surface segregation during the epitaxial growth of GeSn on Si (001) substrates was investigated by Auger electron spectroscopy and energy dispersive X-ray spectroscopy. Sn surface segregation depends on the growth temperature and Sn content of GeSn layers. During Sn surface segregation, Sn-rich nanoparticles form and move on the surface during the deposition, which results in a rough surface owing to facet formation. The Sn-rich nanoparticles moving on the surface during the deposition absorb Sn from the periphery and yield a lower Sn content, not on the surface but within the layer, because the Sn surface segregation and the GeSn deposition occur simultaneously. Sn surface segregation can occur at a lower temperature during the deposition compared with that during postannealing. This suggests that the Sn surface segregation during the deposition is strongly promoted by the migration of deposited Ge and Sn adatoms on the surface originating from the thermal effect of substrate temperature, which also suggests that limiting the migration of deposited Ge and Sn adatoms can reduce the Sn surface segregation and improve the crystallinity of GeSn layers

  9. Time-dependent investigation of sub-monolayers of Ni on Pd using Positron-annihilation induced Auger Electron Spectroscopy and XPS

    Science.gov (United States)

    Zimnik, Samantha; Piochacz, Christian; Vohburger, Sebastian; Hugenschmidt, Christoph

    2016-01-01

    The surface of a polycrystalline Pd-substrate covered with (sub-) monolayers of Ni was investigated with Positron-annihilation induced Auger Electron Spectroscopy (PAES). Comparative studies using conventional AES induced by electrons and X-rays showed the outstanding surface sensitivity of PAES. Time-dependent PAES was performed on a 0.5 ML Ni cover layer on Pd and compared with conventional X-ray induced Photoelectron Spectroscopy (XPS) in order to observe changes in the elemental composition of the surface. The PAES results appear to show a migration of Ni atoms into the Pd substrate, whereas the Ni signal shows a decrease of 12% within 13 h with respect to the initial value.

  10. Surface compositions of atomic layer deposited Zn{sub 1−x}Mg{sub x}O thin films studied using Auger electron spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Ting; Romero, Danilo; Gomez, Romel D., E-mail: rdgomez@umd.edu [Department of Electrical and Computer Engineering, University of Maryland, College Park, Maryland 20742 (United States)

    2015-09-15

    In this paper, the authors present Auger electron spectroscopy (AES) studies of Zn{sub 1−x}Mg{sub x}O (ZMO) films grown via interrupted atomic-layer deposition (ALD) techniques. The ZMO films were fabricated by alternating ALD deposition of ZnO and MgO layers up to 1000 cycles. Zn{sub 1−x}Mg{sub x}O films with progressively decreasing Mg/Zn ratios (Mg/Zn = 1/1, 1/2, 1/3, 1/4, 1/5, 1/6, 1/9, and 2/8, 3/12, 4/16, and 5/20) were fabricated for this study. The AES results exhibit an abrupt drop of Mg composition on the ZMO surface when the Mg/Zn < 1/3. Additionally, the surface composition ratios of O to Mg, O to Zn, and Mg to Zn were estimated with known Auger sensitivity factors. The results indicate that Mg ions diffuse into the bulk, forming Zn{sub 1−x}Mg{sub x}O alloys.

  11. Influence of the "surface effect" on the segregation parameters of S in Fe(100): A multi-scale modelling and Auger Electron Spectroscopy study

    Science.gov (United States)

    Barnard, P. E.; Terblans, J. J.; Swart, H. C.

    2015-12-01

    The article takes a new look at the process of atomic segregation by considering the influence of surface relaxation on the segregation parameters; the activation energy (Q), segregation energy (ΔG), interaction parameter (Ω) and the pre-exponential factor (D0). Computational modelling, namely Density Functional Theory (DFT) and the Modified Darken Model (MDM) in conjunction with Auger Electron Spectroscopy (AES) was utilized to study the variation of the segregation parameters for S in the surface region of Fe(100). Results indicate a variation in each of the segregation parameters as a function of the atomic layer under consideration. Values of the segregation parameters varied more dramatically as the surface layer is approached, with atomic layer 2 having the largest deviations in comparison to the bulk values. This atomic layer had the highest Q value and formed the rate limiting step for the segregation of S towards the Fe(100) surface. It was found that the segregation process is influenced by two sets of segregation parameters, those of the surface region formed by atomic layer 2, and those in the bulk material. This article is the first to conduct a full scale investigation on the influence of surface relaxation on segregation and labelled it the "surface effect".

  12. Application of the Auger and X-ray photoelectron electronic spectroscopies to the study of superficial segregation in the system Pt-Rh

    International Nuclear Information System (INIS)

    The Auger and X-ray photoelectron spectroscopies are applied to the study of the superficial segregation in the system of the binary alloy Pt-Rh. The methodology for the cleaning of the samples, which is essential for the obtainment of reproducible results, has been established. The spectra qualitative analysis allows to identify the element segregated. The application of the Gallon model permits to develop a quantitative study of the phenomenon. (S.M.)

  13. Differential auger spectrometry

    Science.gov (United States)

    Strongin, Myron; Varma, Matesh Narayan; Anne, Joshi

    1976-06-22

    Differential Auger spectroscopy method for increasing the sensitivity of micro-Auger spectroanalysis of the surfaces of dilute alloys, by alternately periodically switching an electron beam back and forth between an impurity free reference sample and a test sample containing a trace impurity. The Auger electrons from the samples produce representative Auger spectrum signals which cancel to produce an Auger test sample signal corresponding to the amount of the impurity in the test samples.

  14. Verification of surface polarity of O-face ZnO(0 0 0 1{sup Macron }) by quantitative modeling analysis of Auger electron spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Su, C.W., E-mail: cwsu@mail.ncyu.edu.tw [Department of Electrophysics, National Chiayi University, 300 Syuefu Rd., Chiayi 60004, Taiwan (China); Huang, M.S.; Tsai, T.H.; Chang, S.C. [Department of Electrophysics, National Chiayi University, 300 Syuefu Rd., Chiayi 60004, Taiwan (China)

    2012-12-15

    Highlights: Black-Right-Pointing-Pointer Quantitative Auger intensity ratios to predict macroscopic surface type to Zn-face or O-face can be obtained using hard sphere model and considering electron mean free paths. Black-Right-Pointing-Pointer Calculation of electron signals from 6-layer depth is the best condition in estimating Auger intensity ratios. Black-Right-Pointing-Pointer The ratio deviated from the estimation reference after surface treated by annealing or sputtering is classified to Zn-rich or O-rich surface. Black-Right-Pointing-Pointer A Zn-rich surface may exist on an O-face surface. Black-Right-Pointing-Pointer Surface type of a composite material can be quickly obtained by quantitative analysis of Auger intensity ratio. - Abstract: Is crystalline ZnO(0 0 0 1{sup Macron }) O-face surface believed to be enriched by Zn atoms? This study may get the answer. We proposed a simplified model to simulate surface concentration ratio on (0 0 0 1{sup Macron })-O or (0 0 0 1)-Zn surface based on the hard-sphere model. The simulation ratio was performed by integrating electron signals from the assumed Auger emission, in which the electron mean free path and relative atomic layer arrangements inside the different polarity ZnO crystal surface were considered as relevant parameters. After counting more than 100 experimental observations of Zn/O ratios, the high frequency peak ratio was found at around 0.428, which was near the value predicted by the proposed model using the IMFP database. The ratio larger than the peak value corresponds to that observed in the annealed samples. A downward trend of the ratio evaluated on the post-sputtering sample indicates the possibility of a Zn-enriched phase appearing on the annealed O-face surface. This phenomenon can further elucidate the O-deficiency debate on most ZnO materials.

  15. Study of the adsorption of methyl iodide and molecular iodine on clean uranium and uranium dioxide surfaces by means of X-ray photoelectron (XPS) and Auger electron spectroscopy (AES)

    International Nuclear Information System (INIS)

    The adsorption of methyl iodide as well as of molecular iodine on uranium metal and on uranium dioxide has been studied at 250C. Surfaces of the substrates were cleaned and characterized before and after exposure using X-ray photoelectron (XPS) and X-ray and electron induced Auger electron (AES) spectroscopy. Exposures amounted up to 1500 L CH3I on uranium metal, 1000 L CH3I on UO2, 100 L I2 on uranium metal, and 75 L I2 on UO2 (1 L = 1 Langmuir = 10-6 torr x sec). From the measured binding energies, Auger parameters, and intensity ratios for substrate and adsorbate constituents we deduced that for both CH3I and I2 on uranium metal a uranium iodide, UI3, is formed. The adsorption of CH3I on U-metal is in addition accompanied by the formation of a carbide-type carbon, UC. Thus, in both cases a dissociative (adsorption/reaction) process is observed. For adsorption of CH3I on UO2 the experimental findings indicate a dissociative process, too, though the species formed could not be identified. In contrast, I2 adsorption on UO2 appears to have non-dissociative character. Saturation coverages for CH3I were found to be approx.= 2 L on U-metal and approx.= 5 L on UO2, for I2 approx.= 40 L on U-metal and 10-15 L on UO2. Variations in the iodine Auger kinetic energy and in the Auger parameter are interpreted in light of extraatomic relaxation processes. (orig.)

  16. Electronic structure of Ti metal and TiO2 powder studied by hard and soft (Cu Kα1 and Al Kα1) X-ray photoelectron and Auger spectroscopy

    International Nuclear Information System (INIS)

    High-energy X-ray photoelectron spectroscopy (XPS) is of particular importance for minimizing the effects of surface contamination by increasing photoelectron escape depths. In this study high-resolution high-energy Cu Kα1 and soft Al Kα1 XPS and Auger electron spectroscopy were used to compare the electronic structure of Ti in TiO2 powder and Ti metal. The Ti 1s in TiO2 XPS line is narrower and more symmetric than in Ti metal. A comparison of the relative intensities of the L23M23M45 and L23M23M23 Auger transitions in Ti metal and TiO2 is consistent with the expected transfer of Ti 3d electrons away from the Ti site in the oxide. The satellites accompanying the Ti 1s XPS line excited by Cu Kα1 X-rays occur at the same energies as the satellites accompanying the Ti 2s and 2p XPS lines excited by Al Kα1 X-rays indicating that they do not depend on the core-level, the experimental resolution or inelastic scattering processes

  17. Photoelectron-Auger electron coincidence study for condensed matter

    Energy Technology Data Exchange (ETDEWEB)

    Stefani, G. [Department of Physics and Unita' INFM, University Roma Tre, Via della Vasca Navale 84, I-00146 Rome (Italy)]. E-mail: stefani@fis.uniroma3.it; Gotter, R. [National Laboratory TASC-INFM, Area Science Park, SS 14 Km 163.5, Basovizza, I-34012 Trieste (Italy); Ruocco, A. [Department of Physics and Unita INFM, University Roma Tre, Via della Vasca Navale 84, I-00146 Rome (Italy); Offi, F. [Department of Physics and Unita INFM, University Roma Tre, Via della Vasca Navale 84, I-00146 Rome (Italy); Pieve, F. Da [Department of Physics and Unita INFM, University Roma Tre, Via della Vasca Navale 84, I-00146 Rome (Italy); Iacobucci, S. [IMIP-CNR Area della Ricerca di Roma, via Salaria Km 29, 3 Montelibretti (Italy); Morgante, A. [National Laboratory TASC-INFM, Area Science Park, SS 14 Km 163.5, Basovizza, I-34012 Trieste (Italy); Verdini, A. [National Laboratory TASC-INFM, Area Science Park, SS 14 Km 163.5, Basovizza, I-34012 Trieste (Italy); Liscio, A. [IMIP-CNR Area della Ricerca di Roma, via Salaria Km 29, 3 Montelibretti (Italy); Yao, H. [Department of Physics and Astronomy and Laboratory of Surface Modification, Rutgers University, 136 Frelinghuysen Road, Piscataway, NJ 08855 (United States); Bartynski, R.A. [Department of Physics and Astronomy and Laboratory of Surface Modification, Rutgers University, 136 Frelinghuysen Road, Piscataway, NJ 08855 (United States)

    2004-12-01

    Advances in materials science have produced a wide array of new solid-state systems with tunable properties and previously unattainable combinations of phenomena that hold the promise of entirely new approaches to technological applications. Invariably, these new materials are increasingly complex and include a large number of constituents in a variety of chemical states. Entirely new theoretical and experimental approaches are needed to gain the insights necessary for intelligent engineering of these materials. In the past 20 years, a steadily increasing number of electron-electron coincidence experiments on atoms and molecules have demonstrated the capability of investigating complicated systems with sensitivity and specificity well beyond the limits imposed by conventional electron spectroscopies. Over the past decade or so, Auger-photoelectron coincidence spectroscopy (APECS) has emerged as a powerful technique for obtaining detailed information about complex materials systems. Moreover, the recent advent of angle-resolved (AR)-APECS has introduced a new level of discrimination in studying the distribution of electrons photoemitted from complex systems. In this review, we describe the basic ideas behind APECS and discuss a study of the SiO{sub 2} system as an example of the unique information this technique can provide. We then introduce the concept of AR-APECS, explain its novel state and angular momentum selectivity that can be used to disentangle information about complex systems that is hidden to conventional spectroscopies. Examples of AR-APECS measurements from Cu, Ge, and graphite that exemplify the capabilities of this technique are presented.

  18. Experimental evidence for extreme surface sensitivity in Auger-Photoelectron Coincidence Spectroscopy (APECS) from solids

    Energy Technology Data Exchange (ETDEWEB)

    Liscio, A.; Gotter, R.; Ruocco, A.; Iacobucci, S.; Danese, A.G.; Bartynski, R.A.; Stefani, G

    2004-07-01

    Core hole creation and subsequent Auger decay processes are studied with unprecedented discrimination by Auger-Photoelectron Coincidence Spectroscopy (APECS). Early works in this field have already pointed out the intrinsic surface sensitivity of these experiments. However, it was not until recently that a model calculation was developed to quantitatively evaluate it. Here we present the first attempt to experimentally establish an effective target thickness for such experiments. The angular distribution of 3p{sub 3/2} photoelectron with kinetic energy of 160 eV is measured in coincidence with the M{sub 3}VV Auger electron with kinetic energy of 55 eV on a Cu (1 1 1) surface. Coincidence and non-coincidence photoelectron angular distributions display differences that, to large extent, are explained by confining the source of the coincident signal within the first two layers of Cu target, thus establishing an experimental upper limit for the effective target thickness of the APECS experiment.

  19. Electron microscopy and auger spectroscopy study of the wetting of the grain boundaries in the systems Mo-Pb, Mo-Sn, Mo-Ni and Ni-Pb

    International Nuclear Information System (INIS)

    Understanding the mechanism of the intergranular penetration of a liquid phase into a metallic solid is an important problem. The structural and chemical characterization of nano-metric films at grain boundaries is now possible by using high resolution electron microscopy associated with X-ray micro-analysis, electron energy loss spectroscopy and Auger spectroscopy. In order to study this problem, two different classes of model materials were selected according to their crystallographic structure: a bcc metal (molybdenum) and an fcc one (nickel). The wetting element was either lead or tin or nickel. In a first approach, the metallic matrix was polycrystalline. The conditions in which the liquid phase penetrates into the grain boundaries were studied by using special preparation and observation techniques. In particular, the use of a Focused Ion Beam microscope (FIB) allowed the preparation of thin foils located very precisely inside the matrix as well as multi-scale observations. These specimens were further observed in electron microscopy with a very high resolution. (authors)

  20. Surface and subsurface oxidation of Mo2C/Mo(100): low-energy ion-scattering, auger electron, angle-resolved X-ray photoelectron, and mass spectroscopy studies.

    Science.gov (United States)

    Ovári, László; Kiss, János; Farkas, Arnold P; Solymosi, Frigyes

    2005-03-17

    The interaction of oxygen with a carburized Mo(100) surface was investigated at different temperatures (300-1000 K). The different information depths of low-energy ion-scattering (LEIS) spectroscopy, with topmost layer sensitivity, Auger electron spectroscopy (AES), and angle-resolved X-ray photoelectron spectroscopy (ARXPS) allowed us to discriminate between reactions on the topmost layer and subsurface transformations. According to ARXPS measurements, a carbide overlayer was prepared by the high-temperature decomposition of C(2)H(4) on Mo(100), and the carbon distribution proved to be homogeneous with a Mo(2)C stoichiometry down to the information depth of XPS. O(2) adsorbs dissociatively on the carbide layer at room temperature. One part of the chemisorbed oxygen is bound to both C and Mo sites, indicated by LEIS. Another fraction of oxygen atoms probably resides in the hollow sites not occupied by C. The removal of C from the outermost layer by O(2), in the form of CO, detected by mass spectroscopy (MS), was observed at 500-600 K. The carbon-depleted first layer is able to adsorb more oxygen compared to the Mo(2)C/Mo(100) surface. Applying higher doses of O(2) at 800 K results in the inward diffusion of O and the partial oxidation of Mo atoms. This process, however, is not accompanied by the removal of C from subsurface sites. The depletion of C from the bulk starts only at 900 K (as shown by MS, AES, and XPS), very probably by the diffusion of C to the surface followed by its reaction with oxygen. At T(ads) = 1000 K, the carbon content of the sample, down to the information depth of XPS, decreased further, accompanied by the attenuation of the C concentration gradient and a substantially decreased amount of oxygen.

  1. Properties of Auger electrons following excitation of polarized atoms by polarized electrons

    Energy Technology Data Exchange (ETDEWEB)

    Kupliauskiene, A. [Institute of Theoretical Physics and Astronomy of Vilnius University, A. Gostauto 12, LT-01108 Vilnius (Lithuania)], E-mail: akupl@itpa.lt; Tutlys, V. [Institute of Theoretical Physics and Astronomy of Vilnius University, A. Gostauto 12, LT-01108 Vilnius (Lithuania)

    2009-01-15

    In non-relativistic approximation, the most general expression for differential cross sections describing the properties of Auger-electron emission induced in the excitation of polarized atoms by polarized electrons is obtained for the first time. The ways of the application of the general expressions suitable for the specific experimental conditions are outlined by deriving the expressions for the asymmetry parameters and the magnetic dichroism of the angular distribution of the Auger electrons as well as of the angular correlations between the scattered and Auger electrons.

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

    International Nuclear Information System (INIS)

    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

  3. Auger electron spectroscopic study of CO{sub 2} adsorption on Zircaloy-4 surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Stojilovic, N.; Farkas, N. [Institute for Teaching and Learning and Departments of Physics and Chemistry, University of Akron, Akron, OH 44325-6236 (United States); Ramsier, R.D. [Institute for Teaching and Learning and Departments of Physics and Chemistry, University of Akron, Akron, OH 44325-6236 (United States)], E-mail: rex@uakron.edu

    2008-02-28

    We investigate the adsorption of CO{sub 2} onto Zircaloy-4 (Zry-4) surfaces at 150, 300 and 600 K using Auger electron spectroscopy (AES). Following CO{sub 2} adsorption at 150 K the graphitic form of carbon is detected, whereas upon chemisorption at 300 and 600 K we detect the carbidic phase. As the adsorption temperature is increased, the carbon Auger signal increases, whereas the oxygen signal decreases. Adsorption at all three temperatures results in a shift of the Zr Auger features, indicating surface oxidation. The effect of adsorbed CO{sub 2} on the Zr(MVV) and Zr(MNV) transitions depends on adsorption temperature and is less pronounced at higher temperatures. On the other hand, changes in the Zr(MNN) feature are similar for all three adsorption temperatures. The changes in the Zr Auger peak shapes and positions are attributed to oxygen from dissociated CO{sub 2}, with the differences observed at various temperatures indicative of the diffusion of oxygen into the subsurface region.

  4. Ramsey method for Auger-electron interference induced by an attosecond twin pulse

    OpenAIRE

    Buth, Christian; Schafer, Kenneth J.

    2010-01-01

    We examine the archetype of an interference experiment for Auger electrons: two electron wave packets are launched by inner-shell ionizing a krypton atom using two attosecond light pulses with a variable time delay. This setting is an attosecond realization of the Ramsey method of separated oscillatory fields. Interference of the two ejected Auger-electron wave packets is predicted, indicating that the coherence between the two pulses is passed to the Auger electrons. For the detection of the...

  5. 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

  6. Ultrafast Molecular Three-Electron Collective Auger Decay

    Science.gov (United States)

    Feifel, Raimund

    2016-06-01

    A new class of many-electron Auger transitions in atoms was initially proposed over 40 years ago, but the first tentative evidence for its real existence was only adduced by Lee et al. in 1993, on the basis of the resonant Auger spectrum of Kr. Using a multi-electron coincidence technique with synchrotron radiation, we unambiguously showed very recently that the transition suggested by Lee et al. in Kr really does take place, but with a rather small branching ratio. Related inter-atomic three-electron transitions in rare gas clusters were recently predicted by Averbukh and Kolorenc and demonstrated by Ouchi et al.. From consideration of the energy levels involved it seems that the basic three-electron process could occur in molecules too, wherever a double inner-valence shell vacancy lies at a higher energy than the molecular triple ionisation onset. Experiments on CH_3F reveal for the first time the existence of this new decay pathway there, and calculations show that despite its three-electron nature, its effective oscillator strength is orders of magnitudes higher than in atoms, allowing an efficient competition with both molecular dissociation and two-electron decay channels on the ultrafast time scale. The dramatic enhancement of the molecular three-electron Auger transition can be explained in terms of a partial breakdown of the molecular orbital picture of ionisation. We predict that the collective decay pathway will be significant in a wide variety of heteroatomic molecules ionised by extreme UV and soft X-rays, particularly at Free-Electron-Lasers where double inner-shell vacancies can be created efficiently by two-photon transitions. G.N. Ogurtsov et al., Sov. Phys. Tech. Phys. 15, 1656 (1971) and V.V. Afrosimov et al., JETP Lett. 21, 249 (1975). I. Lee, R. Wehlitz, U. Becker and M. Ya. Amusia, J. Phys. B: At. Mol. Opt. Phys. 26, L41 (1993). J.H.D. Eland, R.J. Squibb, M. Mucke, S. Zagorodskikh, P. Linusson, and R. Feifel, New J. Phys. 17, 122001 (2015). V

  7. Digital electronics for the Pierre Auger Observatory AMIGA muon counters

    Science.gov (United States)

    Wainberg, O.; Almela, A.; Platino, M.; Sanchez, F.; Suarez, F.; Lucero, A.; Videla, M.; Wundheiler, B.; Melo, D.; Hampel, M. R.; Etchegoyen, A.

    2014-04-01

    The ``Auger Muons and Infill for the Ground Array'' (AMIGA) project provides direct muon counting capacity to the Pierre Auger Observatory and extends its energy detection range down to 0.3 EeV. It currently consists of 61 detector pairs (a Cherenkov surface detector and a buried muon counter) distributed over a 23.5 km2 area on a 750 m triangular grid. Each counter relies on segmented scintillator modules storing a logical train of `0's and `1's on each scintillator segment at a given time slot. Muon counter data is sampled and stored at 320 MHz allowing both the detection of single photoelectrons and the implementation of an offline trigger designed to mitigate multi-pixel PMT crosstalk and dark rate undesired effects. Acquisition is carried out by the digital electronics built around a low power Cyclone III FPGA. This paper presents the digital electronics design, internal and external synchronization schemes, hardware tests, and first results from the Observatory.

  8. Digital Electronics for the Pierre Auger Observatory AMIGA Muon Counters

    CERN Document Server

    Wainberg, O; Platino, M; Sanchez, F; Suarez, F; Lucero, A; Videla, M; Wundheiler, B; Melo, D; Hampel, M; Etchegoyen, A

    2013-01-01

    The "Auger Muons and Infill for the Ground Array" (AMIGA) project provides direct muon counting capacity to the Pierre Auger Observatory and extends its energy detection range down to 0.3 EeV. It currently consists of 61 detector pairs (a Cherenkov surface detector and a buried muon counter) distributed over a 23.5 km2 area on a 750 m triangular grid. Each counter relies on segmented scintillator modules storing a logical train of '0's and '1's on each scintillator segment at a given time slot. Muon counter data is sampled and stored at 320 MHz allowing both the detection of single photoelectrons and the implementation of an offline trigger designed to mitigate multi-pixel PMT crosstalk and dark rate undesired effects. Acquisition is carried out by the digital electronics built around a low power Cyclone III FPGA. This paper presents the digital electronics design, internal and external synchronization schemes, hardware tests, and first results from the Observatory.

  9. Observation of resonance recombination lines in electron excited Auger spectra of Gd

    International Nuclear Information System (INIS)

    Combined measurements of electron excited Nsub(4,5) Auger spectra and photoelectron emission on clean and oxidized Gd lead to a distinction between Auger lines originating from 4d → continuum and 4d → 4f resonance excitations. Several Auger structures are identified as due to the direct recombination of 4d94f8 states with the 4f and valence electrons. The shape of the most prominent Auger line for oxidized Gd agrees perfectly with the Fano profile of the 4f photoemission intensity. (orig.)

  10. Challenges for lithium species identification in complementary Auger and X-ray photoelectron spectroscopy

    Science.gov (United States)

    Hoffmann, M.; Zier, M.; Oswald, S.; Eckert, J.

    2015-08-01

    The combination of high spatial resolution and near-surface chemical information makes Auger electron spectroscopy (AES) a powerful tool for comprehensive surface analysis. The recent interest in lithium metal as an active material in lithium sulphur or lithium air batteries increases the demand for a thorough knowledge of the reactions happening at the electrode interface. Applying AES to the complex surfaces of batteries, however, requires a detailed understanding of the interactions occurring with the highly reactive materials during investigation, especially when using metallic lithium with its passivation layers formed even under glove box atmosphere. The article is focused on the influence of electron beam damage and residual gas under ultra-high vacuum conditions on the observations made. Immediate irradiation effects are shown to highly depend on electron dose leading to misinterpretation the surface composition and a non-sufficient stability of the sample. The results are further supported by coupled X-ray photoelectron spectroscopy (XPS) measurements that help to understand the beam induced phenomena. An improved output of the spectroscopic measurement could be achieved employing AES mappings. This allows an improved insight into the local distribution of different lithium compounds in the material surface and can also be applied to other battery active materials.

  11. Auger electron and X-ray photoelectron spectroscopic study of the biocorrosion of copper by alginic acid polysaccharide

    Science.gov (United States)

    Jolley, John G.; Geesey, Gill G.; Hankins, Michael R.; Wright, Randy B.; Wichlacz, Paul L.

    1989-08-01

    Thin films (3.4 nm) of copper on germanium substrates were exposed to 2% alginic acid polysaccharide aqueous solution. Pre- and post-exposure characterization were done by Auger electron spectroscopy and X-ray photoelectron spectroscopy. Ancillary graphite furnace atomic absorption spectroscopy was used to monitor the removal process of the copper thin film from the germanium substrate. Results indicate that some of the copper was oxidized by the alginic acid solution. Some of the copper was removed from the Cu/Ge interface and incorporated into the polymer matrix. Thus, biocorrosion of copper was exhibited by the alginic acid polysaccharide.

  12. Angle-Resolved Auger Spectroscopy as a Sensitive Access to Vibronic Coupling

    Science.gov (United States)

    Knie, A.; Patanen, M.; Hans, A.; Petrov, I. D.; Bozek, J. D.; Ehresmann, A.; Demekhin, Ph. V.

    2016-05-01

    In the angle-averaged excitation and decay spectra of molecules, vibronic coupling may induce the usually weak dipole-forbidden transitions by the excitation intensity borrowing mechanism. The present complementary theoretical and experimental study of the resonant Auger decay of core-to-Rydberg excited CH4 and Ne demonstrates that vibronic coupling plays a decisive role in the formation of the angle-resolved spectra by additionally involving the decay rate borrowing mechanism. Thereby, we propose that the angle-resolved Auger spectroscopy can in general provide very insightful information on the strength of the vibronic coupling.

  13. Digital Electronics for the Pierre Auger Observatory AMIGA Muon Counters

    OpenAIRE

    Wainberg, O.; A. Almela; Platino, M.; Sanchez, F.; Suarez, F.; Lucero, A.; Videla, M.; B. Wundheiler; Melo, D.; Hampel, M.; Etchegoyen, A.

    2013-01-01

    The "Auger Muons and Infill for the Ground Array" (AMIGA) project provides direct muon counting capacity to the Pierre Auger Observatory and extends its energy detection range down to 0.3 EeV. It currently consists of 61 detector pairs (a Cherenkov surface detector and a buried muon counter) distributed over a 23.5 km2 area on a 750 m triangular grid. Each counter relies on segmented scintillator modules storing a logical train of '0's and '1's on each scintillator segment at a given time slo...

  14. Photoelectron Spectroscopy of Ions: Study of the Auger Decay of the 4d→nf (n=4,5) Resonances in Xe^{5+} Ion.

    Science.gov (United States)

    Bizau, J-M; Cubaynes, D; Guilbaud, S; Penent, F; Lablanquie, P; Andric, L; Palaudoux, J; Al Shorman, M M; Blancard, C

    2016-03-11

    We have studied, for the first time by electron spectroscopy, the Auger decay of the 4d→nf (n=4,5) resonances in Xe^{5+} ion. By detecting in coincidence the Auger electrons with the resulting Xe^{6+} ions, we unravel the contribution of the different final ionic states to the total cross section measured by ion spectroscopy. A strong intensity of 5s5p satellite lines has been observed, up to 4 times stronger than the 5s^{2} main lines. This unexpected behavior is confirmed by multiconfiguration Dirac-Fock calculations. This technique provides the most stringent test for theoretical models and allows us to disentangle the contribution of ions in the ground and metastable states in the target beam. PMID:27015477

  15. Metrological electron spectroscopy:AES%计量学的电子谱:俄歇电子能谱

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    @@ Electron spectroscopy is now very popular particularly in surface analysis.Many manufacturers make their sophisticated machines,in which Auger electron spectroscopy(AES)and X-ray photoelectron spectroscopy (XPS)have been widely distributed and commonly used.Although,the electron spectroscopy is not in the category of metrology,i.e.,the SI(system international).

  16. Validation of 64Cu-ATSM damaging DNA via high-LET Auger electron emission

    International Nuclear Information System (INIS)

    Radioactive copper (II) (diacetyl-bis N4-methylthiosemicarbazone) (Cu-ATSM) isotopes were originally developed for the imaging of hypoxia in tumors. Because the decay of a 64Cu atom is emitting not only positrons but also Auger electrons, this radionuclide has great potential as a theranostic agent. However, the success of 64Cu-ATSM internal radiation therapy would depend on the contribution of Auger electrons to tumor cell killing. Therefore, we designed a cell culture system to define the contributions to cell death from Auger electrons to support or refute our hypothesis that the majority of cell death from 64Cu-ATSM is a result of high-LET Auger electrons and not positrons or other low-LET radiation. Chinese hamster ovary (CHO) wild type and DNA repair–deficient xrs5 cells were exposed to 64Cu-ATSM during hypoxic conditions. Surviving fractions were compared with those surviving gamma-radiation, low-LET hadron radiation, and high-LET heavy ion exposure. The ratio of the D10 values (doses required to achieve 10% cell survival) between CHO wild type and xrs5 cells suggested that 64Cu-ATSM toxicity is similar to that of high-LET Carbon ion radiation (70 keV/μm). γH2AX foci assays confirmed DNA double-strand breaks and cluster damage by high-LET Auger electrons from 64Cu decay, and complex types of chromosomal aberrations typical of high-LET radiation were observed after 64Cu-ATSM exposure. The majority of cell death was caused by high-LET radiation. This work provides strong evidence that 64Cu-ATSM damages DNA via high-LET Auger electrons, supporting further study and consideration of 64Cu-ATSM as a cancer treatment modality for hypoxic tumors. (author)

  17. Radiotoxicity induced by auger electron emitters in human osteosarcoma cell line using comet assay

    International Nuclear Information System (INIS)

    The comet assay (single cell gel electrophoresis assay) was used to evaluate the radiotoxicity of Auger electron emitters in the human osteosarcoma cell line (HOS-8603). After internal exposure to 67Ga-EDTMP, the sarcoma cell has been injured severely. The comet length was longer along with the increase of dose, the appearance of comet tail was different from that with respect to the 60Co γ-ray irradiation. DNA damage of cell was mainly due to the radiation effect of Auger electrons. The 67Ga may be a therapeutic radionuclide with good prospect for tumor treatment and palliation of bone pain induced by metastasis

  18. 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.

  19. Communication: Formation of slow electrons in the Auger decay of core-ionized water molecules

    Science.gov (United States)

    Hikosaka, Y.; Yamamoto, K.; Nakano, M.; Odagiri, T.; Soejima, K.; Suzuki, I. H.; Lablanquie, P.; Penent, F.; Ito, K.

    2012-11-01

    Double Auger decay of O1s-1 and its satellite states in H2O has been studied with a multi-electron coincidence method, and a process leading to autoionizing O* fragments has been revealed. The breaking of the two O-H bonds producing the autoionizing O* fragments occurs for highly excited H2O2+ populated by the initial Auger decay. The O* fragments are more favorably produced in the decay from the satellite states, resulting from the larger population of highly excited H2O2+ states inheriting the valence excitation in the initial state.

  20. Surface sensitivity effects with local probe scanning Auger-scanning electron microscopy

    NARCIS (Netherlands)

    Van Agterveld, DTL; Palasantzas, G; De Hosson, JTM; Bentley, J; Allen, C; Dahmen, U; Petrov,

    2001-01-01

    Ultra-high-vacuum segregation studies on in-situ fractured Cu-Sb alloys were performed in terms of nanometer scale scanning Auger/Electron microscopy. S contamination leads to the formation Of Cu2S precipitates which, upon removal due to fracture, expose pits with morphology that depends on the prec

  1. Relationship between chromatin structure and sensitivity to molecularly targeted auger electron radiation therapy.

    NARCIS (Netherlands)

    Terry, S.Y.A.; Vallis, K.A.

    2012-01-01

    PURPOSE: The open structure of euchromatin renders it susceptible to DNA damage by ionizing radiation (IR) compared with compact heterochromatin. The effect of chromatin configuration on the efficacy of Auger electron radiotherapy was investigated. METHODS AND MATERIALS: Chromatin structure was alte

  2. Electron energy loss spectroscopy in advanced materials

    Energy Technology Data Exchange (ETDEWEB)

    Zaluzec, N.J.

    1991-01-01

    The combination of a Transmission Electron Microscope (TEM) with an electron energy loss spectrometer (EELS) yields a powerful tool for the microcharacterization of materials. However, the application of this technique to advanced materials problems can only be fully appreciated when the information obtained using EELS is related to that obtained from other analytical spectroscopies. In this chapter, we briefly discuss the relative performance of X-ray, Auger and Photoelectron Spectroscopies with EELS pointing out the limitations and merits of each. This comparison is followed by examples of the application of EELS to investigations involving high {Tc} superconductors, artificial metallic superlattices, amorphous magnetic materials and the characterization of metallic hydride phases. 14 refs., 22 figs.

  3. Calculations of energies and absolute intensities of Auger electrons and X-rays arising from electron capture decay

    Institute of Scientific and Technical Information of China (English)

    ZHOU Chun-Mei; WU Zhen-Dong; HUANG Xiao-Long

    2005-01-01

    Calculations of energies and absolute intensities of Auger electron and X-ray arising from electron capture are introduced briefly. The calculation codes and main process are also presented. The application is also given by taking 55Fe ε decay as an example.

  4. Fragmentation of CF3Br induced by fluroine is core excitation: Energy resolved auger electron multiple-ion coincidence measurements

    International Nuclear Information System (INIS)

    Fragmentation processes in CF3Br near the F K edge were investigated using synchrotron radiation and Energy Resolved Auger Electron Multiple Ion Coincidence (ERAEMICO). Time-of flight mass spectra were collected in coincidence with either selected F 1s Auger or resonant-Auger electrons which were energy analyzed with a hemispherical detector. In addition, a more inclusive mass spectrum was taken near the F 1s ionization potential in coincidence with low energy electrons. Preliminary spectra the Br2+ ion intensity is negligible and the relative CF+ abundance is higher. These differences confirm the notion that the electronic state prior to bond breakage governs the resulting fragmentation pattern

  5. Site-selective resonant Auger spectroscopy of iso-dichloroethylene at the carbon K-edge

    International Nuclear Information System (INIS)

    Highlights: ► We provide detailed results on electron decay following core excitations to two carbon atoms to the LUMO in different chemical environments to the LUMO in CH2=CCl2. ► The experimental results are compared with high-quality theoretical calculations. ► We report calculated valence spectra in the ground-state, C (CH2) and C (CCl2) core-excited states. -- Abstract: This study focuses on the two C1s-to-LUMO (lowest unoccupied molecular orbital) excitations of the iso-dichloroethylene (H2C=CCl2) and the subsequent Auger decay. We investigate the effect of the two different carbon core excitations on the population of the cation produced after electronic relaxation. The resonant Auger spectra are interpreted by comparison to the valence shells photoionization spectrum and with the help of theoretical calculations. Several consequences of the core-hole localization on the electronic decay are observed. In particular, the resonant excitation of the C1s(CH2) to the LUMO leads to a large intensity increase in the region of the first satellite state, whereas no dramatic changes are observed for the C1s(CCl2) excitation.

  6. Studies of the AgM5N45N4.5 spectrum of disordered Ag0.5Pd0.5 alloy by Auger photoelectron coincidence spectroscopy (APECS)

    International Nuclear Information System (INIS)

    Full text: The Auger electron emission process from solids is very complex, with a range of intrinsic processes producing intensity in final spectra. These processes can include the basic Auger process, initial- and final-states, shake-up/off and Coster-Kronig (CK) processes. Auger Photoelectron Coincidence Spectroscopy (APECS) is a technique to detect the Auger electron only when the 'initial' photoelectron also is detected. By counting those Auger electrons that arrive in coincidence with a photoelectron of certain binding energy, the initial state is uniquely determined, thus controlling the magnitude of various satellites of the Auger spectrum. AxPd1-x is a disordered alloy. XPS spectra indicated that the FWHM of Ag 3d5/2 increases from 0.56 eV in pure Ag to 0.77 eV in Ag0.5Pd0.5. The disorder broadening of the Ag 3d core line in AgPd is due to the spread of local potentials in the atomic cores arising from the effects of charge transfer. In this study, an effect of disorder broadening of the core level photoelectron line on the Ag MVV Auger spectra in random substituted Ag0.5Pd0.5 alloy has been investigated by APECS. Data were collected for the AgM5V45V45 Auger line in coincidence with Ag 3d photoelectron lines. It is shown that the broadening of the AgM5V45V45 line is directly associated with the presence of disorder broadening of the Ag 3d5/2 photoelectron line

  7. Contribution of scanning Auger microscopy to electron beam damage study

    International Nuclear Information System (INIS)

    Electron bombardment can produce surface modifications of the analysed sample. The electron beam effects on solid surfaces which have been discussed in the published literature can be classified into the following four categories: (1) heating and its consequent effects, (2) charge accumulation in insulators and its consequent effects, (3) electron stimulated adsorption (ESA), and (4) electron stimulated desorption and/or decomposition (ESD). In order to understand the physico-chemical processes which take place under electron irradiation in an Al-O system, we have carried out experiments in which, effects, such as heating, charging and gas contamination, were absent. Our results point out the role of an enhanced surface diffusion of oxygen during electron bombardment of an Al (111) sample. The importance of this phenomenon and the contribution of near-elastic scattering of the primary electrons (5 keV) to the increase of the oxidation degree observed on Al (111) are discussed, compared to the generally studied effects

  8. Doppler effect in fluorine K-Auger line produced in electron-induced core ionization of SF6.

    Science.gov (United States)

    Mondal, S; Singh, R K; Shanker, R

    2006-01-21

    An experimental evidence is reported on the observation of the Doppler effect in fluorine K-Auger line emitted from a core-ionized SF6 molecule under an impact of 16 keV electrons. The emitting source of the Auger line is found to acquire a kinetic energy of 4.7+/-0.3 keV. We propose that such large energy is released from the Coulomb repulsion taking place between F+ and SF5+ fragment ions under influence of an intense focusing field of the incident electrons. In the presence of the Coulomb field of these ions, the Auger line obtains a polarization P = 76%+/-7%.

  9. 123I: Calculation of the Auger electron spectrum and assessment of the strand breakage efficiency

    International Nuclear Information System (INIS)

    Auger cascades induced by electron capture in 123I have been simulated by the Monte Carlo technique with special emphasis on the determination of the electron kinetic energies. By using an approach which considers the individual electron population of all electronic shells before and after a transition, errors in the electron energy normally introduced when applying the so-called (Z+1)-approximation are avoided. Thus, the energy of the electrons released in transitions between higher shells were found to be about half the value mentioned in the literature. An average total number of 7.6 electrons (6.4 Auger-, and 1.2 shake-off electrons) has been determined to be emitted per decay, a number which is considerably lower than those reported in similar studies. The efficiency of strand break induction has been assessed to be 0.4 DSB and 1.1 additional SSB per decay of DNA bound 123I. A comparison with the corresponding DSB values of 125I reveals that 125I is 2.5 times more effective than 123I. This is about the same ratio as that determined by Makrigiorgos on the basis of cell killing experiments

  10. Distribution of strand breaks produced by Auger electrons in decay of iodine 125 in triplex DNA

    International Nuclear Information System (INIS)

    In this study we investigate the possibility of using Auger electrons as a probing agent for the study of structures of nucleic acids. To this end, we present the distribution of breaks produced in strands of a DNA duplex and a triplex-forming oligonucleotide (TFO) carrying Auger emitting radionuclide 125I. The method of calculation includes use of a molecular model of plasmid DNA duplex with bound TFO carrying a labelled 125I at position C5 of a single deoxycytosine residue, a source of Auger spectra, Monte Carlo electron track structure and the ensuing chemistry codes, to simulate the distribution of breaks produced in both strands of a plasmid DNA. Frequencies of fragment length distributions were obtained for the TFO, the purine and the pyrimidine strands. The frequency of breaks in the purine strand showed good correlation with the published experimental results, while that for the pyrimidine strand is lower by a factor of 3. It is concluded that the true structure of triplex DNA may not be purely of B-form

  11. Distribution of strand breaks produced by Auger electrons in decay of iodine 125 in triplex DNA

    Energy Technology Data Exchange (ETDEWEB)

    Nikjoo, H.; Panyutin, I.G.; Terrissol, M.; Vrigneaud, J.M.; Laughton, C.A. [MRC Radiation and Genome Stability Unit, Harwell (United Kingdom)

    2000-11-01

    In this study we investigate the possibility of using Auger electrons as a probing agent for the study of structures of nucleic acids. To this end, we present the distribution of breaks produced in strands of a DNA duplex and a triplex-forming oligonucleotide (TFO) carrying Auger emitting radionuclide {sup 125}I. The method of calculation includes use of a molecular model of plasmid DNA duplex with bound TFO carrying a labelled {sup 125}I at position C5 of a single deoxycytosine residue, a source of Auger spectra, Monte Carlo electron track structure and the ensuing chemistry codes, to simulate the distribution of breaks produced in both strands of a plasmid DNA. Frequencies of fragment length distributions were obtained for the TFO, the purine and the pyrimidine strands. The frequency of breaks in the purine strand showed good correlation with the published experimental results, while that for the pyrimidine strand is lower by a factor of 3. It is concluded that the true structure of triplex DNA may not be purely of B-form.

  12. Satellite X-ray lines and KLL Auger electrons from fluorine compounds

    International Nuclear Information System (INIS)

    Fluorine K X-rays are excited by irradiation of solid samples (LiF, NaF, KF, RbF, CsF, AgF; BeF2, MgF2, CaF2, CrF2, FeF2, CoF2, NiF2, CuF2, SnF2, ZnF2, PbF2, BaF2) with α-particles. Optimal conditions for the observation of Kαsub(3,4) satellites from thick samples are obtained with 2 MeV4He+ particles from a Van de Graaff generator. X-rays are analysed with a Bragg spectrometer equipped with a flat crystal of TIAP, the resolution is 1.2 eV for Fluorine K X-rays. Auger electrons are excited by irradiation of same samples with Al Kαsub(1,2) X-rays; electrons from the main KLL Auger line are detected with a resolution of about 1 eV. The observations made on these compounds are in accordance with previous data on a few samples as reported by Deconninck et al. (1978). Important variations in shape and amplitude are observed in Kαsub(3,4) X-ray and KLL Auger spectra. The relative amplitude of the Kαsub(3,4) peak is maximum in ionic compound and the peak width is narrower, this amplitude decreases with increasing covalency and the presence of energy band is observed by the energy spreading of the peaks (X-ray and Auger). The competition between different decay modes is investigated in an attempt to interpretate the relative amplitude of the satellite peaks. (author)

  13. 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.

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

    Science.gov (United States)

    Kleifges, M.

    2016-07-01

    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 km2. 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.

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

    International Nuclear Information System (INIS)

    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 of this

  16. 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

  17. Radiotoxicity induced by Auger electron emitters in human osteosarcoma cell line using comet assay

    Institute of Scientific and Technical Information of China (English)

    XU Yu-Jie; LI Qing-Nuan; ZHU Ran; ZHU Ben-Xing; ZHANG Yong-Ping; ZHANG Xiao-Dong; FAN Wo; HONG Cheng-Jiao; LI Wen-Xin

    2003-01-01

    The comet assay (single cell gel electrophoresis assay) was used to evaluate the radiotoxicity of Augerelectron emitters in the human osteosarcoma cell line (HOS-8603). After internal exposure to 67Ga-EDTMP, the sar-coma cell has been injured severely. The comet length was longer along with the increase of dose, the appearance ofcomet tail was different from that with respect to the 60Co γ-ray irradiation. DNA damage of cell was mainly due tothe radiation effect of Auger electrons. The 67Ga may be a therapeutic radionuclide with good prospect for tumortreatment and palliation of bone pain induced by metastasis.

  18. Kinetic energies to analyze the experimental auger electron spectra by density functional theory calculations

    Science.gov (United States)

    Endo, Kazunaka

    2016-02-01

    In the Auger electron spectra (AES) simulations, we define theoretical modified kinetic energies of AES in the density functional theory (DFT) calculations. The modified kinetic energies correspond to two final-state holes at the ground state and at the transition-state in DFT calculations, respectively. This method is applied to simulate Auger electron spectra (AES) of 2nd periodic atom (Li, Be, B, C, N, O, F)-involving substances (LiF, beryllium, boron, graphite, GaN, SiO2, PTFE) by deMon DFT calculations using the model molecules of the unit cell. Experimental KVV (valence band electrons can fill K-shell core holes or be emitted during KVV-type transitions) AES of the (Li, O) atoms in the substances agree considerably well with simulation of AES obtained with the maximum kinetic energies of the atoms, while, for AES of LiF, and PTFE substance, the experimental F KVV AES is almost in accordance with the spectra from the transitionstate kinetic energy calculations.

  19. Density of Trap States and Auger-mediated Electron Trapping in CdTe Quantum-Dot Solids.

    Science.gov (United States)

    Boehme, Simon C; Azpiroz, Jon Mikel; Aulin, Yaroslav V; Grozema, Ferdinand C; Vanmaekelbergh, Daniël; Siebbeles, Laurens D A; Infante, Ivan; Houtepen, Arjan J

    2015-05-13

    Charge trapping is an ubiquitous process in colloidal quantum-dot solids and a major limitation to the efficiency of quantum dot based devices such as solar cells, LEDs, and thermoelectrics. Although empirical approaches led to a reduction of trapping and thereby efficiency enhancements, the exact chemical nature of the trapping mechanism remains largely unidentified. In this study, we determine the density of trap states in CdTe quantum-dot solids both experimentally, using a combination of electrochemical control of the Fermi level with ultrafast transient absorption and time-resolved photoluminescence spectroscopy, and theoretically, via density functional theory calculations. We find a high density of very efficient electron traps centered ∼0.42 eV above the valence band. Electrochemical filling of these traps increases the electron lifetime and the photoluminescence quantum yield by more than an order of magnitude. The trapping rate constant for holes is an order of magnitude lower that for electrons. These observations can be explained by Auger-mediated electron trapping. From density functional theory calculations we infer that the traps are formed by dicoordinated Te atoms at the quantum dot surface. The combination of our unique experimental determination of the density of trap states with the theoretical modeling of the quantum dot surface allows us to identify the trapping mechanism and chemical reaction at play during charge trapping in these quantum dots. PMID:25853555

  20. Sputtering measurements on CTR materials using Auger electron spectroscopy

    International Nuclear Information System (INIS)

    The sputter yield of Nb, W, C, and Ag by Ar+ in the energy range from 0.5 to 1.5 keV was measured. In addition, the sputter yield for W, C and Ag by H+ at 11.0 keV has been determined. With the exception of carbon, the data are in general agreement with earlier work. For carbon, some discrepancies between the present work and earlier studies are found. It is suggested that major factors contributing to these discrepancies are structural and/or chemical in nature

  1. Improvements upon the continuum wavefunctions of Auger electrons by use of the least-squares variational method

    International Nuclear Information System (INIS)

    A variational least-squares technique is developed to obtain an iterative improvements upon the wavefunctions of Auger electrons emitted by the ion Ar2+. The core potentials seen by the Auger electrons are evaluated on the basis of the Hartree-Fock orbitals delivered by the conventional Hartree-Fock programs. In order to illustrate our technique, the transition rates of the Auger electrons emitted from Ar corresponding to different configurations, namely 1s → 3p 3p, 1s → 3s 3s, 1s → 2s 2s, 1s → 2p 2p, 1s → 2s 3s and 1s → 2p 3p are calculated. (author)

  2. Electron spectroscopy with fast heavy ions

    International Nuclear Information System (INIS)

    Since about 1970 the spectroscopy of Auger-electrons and characteristic x-rays following energetic ion-atom collisions has received a great deal of attention. An increasing number of accelerators, capable of providing a large number of projectile ion species over a wide range of projectile energies, became available for studying ion-atom collision phenomena. Many charged particles from protons up to heavy ions like uranium can be accelerated to energies ranging over six orders of magnitude. This allows us to study systematically a great variety of effects accompanied by dynamic excitation processes of the atomic shells in either the projectile- or target-atoms. The studies yield fundamental information regarding the excitation mechanism (e.g., Coulomb and quasi-molecular excitation) and allow sensitive tests of atomic structure theories. This information in turn is valuable to other fields in physics like plasma-, astro-, or solid-state (surface) physics. It is a characteristic feature of fast heavy-ion accelerators that they can produce highly stripped ion species which have in turn the capability to highly ionize neutral target atoms or molecules in a single collision. The ionization process, mainly due to the strong electrical fields that are involved, allows us to study few-electron atoms with high atomic numbers Z. High resolution spectroscopy performed with these atoms allows a particularly good test of relativistic and QED effects. The probability of producing these few electron systems is determined by the charge state and the velocity of the projectile ions. In this contribution the possibilities of using electron spectroscopy as a tool to investigate fast ion-atom collisions is discussed and demonstrated with a few examples. 30 references

  3. Electron spectroscopy of dilute nitrides

    International Nuclear Information System (INIS)

    The application of electron spectroscopies in dilute nitride semiconductor research for both chemical analysis and the determination of electronic and lattice vibrational properties is described. X-ray photoelectron spectroscopy of the nitrogen bonding configurations in dilute InNxSb1-x and InNxAs1-x alloys is presented. High resolution electron-energy-loss spectroscopy (HREELS) of the plasmon excitations in InNxSb1-x is shown to provide information on the electronic properties of the material, before and after annealing. HREELS is also used to investigate the GaN-like phonon modes in GaNxAs1-x alloys

  4. Investigation of low-Z Coster-Kronig transitions by means of Auger and photoelectron spectroscopy

    Science.gov (United States)

    Yin, L. I.; Tsang, T.; Adler, I.

    1972-01-01

    Experimental intensity ratios of Auger transitions for Co, Ni, Cu, and Zn as well as the relative L sub 2 and L sub 3 level widths of Cu and Zn, derived from their photoelectron spectra, are presented. Evidence is presented that a great deal of vacancy reorganization took place following photoionization and prior to Auger emission. These reorganizations are assumed to be due to Coster-Kronig transitions f sub 23. These results are compared with theoretical calculations and agree with predicted discontinuity at Z = 30 where f sub 23 transitions become energetically impossible.

  5. Oxidation of metals and alloys in controlled atmospheres using in situ transmission electron microscopy and Auger spectrography

    Science.gov (United States)

    Rao, D. B.; Heinemann, K.; Douglass, D. L.

    1976-01-01

    Single-crystalline thin films of copper were oxidized at an isothermal temperature of 425 C and at an oxygen partial pressure of .005 Torr in situ in a high-resolution electron microscope. The specimens were prepared by epitaxial vapor deposition onto polished 100 and 110 faces of rocksalt and mounted in a hot stage inside an ultra-high-vacuum specimen chamber of the microscope. Large amounts of sulfur, carbon, and oxygen were detected by Auger electron spectroscopy on the surface of the as-received films and were removed in situ by ion-sputter etching immediately prior to the oxidation. The nucleation and growth characteristics of Cu2O on Cu were studied. Results show that neither stacking faults nor dislocations are associated with the Cu2O nucleation sites. The growth of Cu2O nuclei is linear with time. The experimental findings, including results from oxygen dissolution experiments and from repetitive oxidation-reduction-oxidation sequences, fit well into the framework of an oxidation process involving (a) the formation of a surface-charge layer, (b) oxygen saturation in the metal and (c) nucleation, followed by surface diffusion of oxygen and bulk diffusion of copper for lateral and vertical oxide growth, respectively.

  6. Relationship Between Chromatin Structure and Sensitivity to Molecularly Targeted Auger Electron Radiation Therapy

    Energy Technology Data Exchange (ETDEWEB)

    Terry, Samantha Y.A. [CR-UK/MRC Gray Institute for Radiation Oncology and Biology, Department of Oncology, University of Oxford, Oxford (United Kingdom); Vallis, Katherine A., E-mail: katherine.vallis@oncology.ox.ac.uk [CR-UK/MRC Gray Institute for Radiation Oncology and Biology, Department of Oncology, University of Oxford, Oxford (United Kingdom)

    2012-07-15

    Purpose: The open structure of euchromatin renders it susceptible to DNA damage by ionizing radiation (IR) compared with compact heterochromatin. The effect of chromatin configuration on the efficacy of Auger electron radiotherapy was investigated. Methods and Materials: Chromatin structure was altered in MDA-MB-468 and 231-H2N human breast cancer cells by suberoylanilide hydroxamic acid (SAHA), 5-aza-2-deoxycytidine, or hypertonic treatment. The extent and duration of chromatin structural changes were evaluated using the micrococcal nuclease assay. DNA damage ({gamma}H2AX assay) and clonogenic survival were evaluated after exposure to {sup 111}In-DTPA-hEGF, an Auger electron-emitting radiopharmaceutical, or IR. The intracellular distribution of {sup 111}In-DTPA-hEGF after chromatin modification was investigated in cell fractionation experiments. Results: Chromatin remained condensed for up to 20 minutes after NaCl and in a relaxed state 24 hours after SAHA treatment. The number of {gamma}H2AX foci per cell was greater in MDA-MB-468 and 231-H2N cells after IR (0.5 Gy) plus SAHA (1 {mu}M) compared with IR alone (16 {+-} 0.6 and 14 {+-} 0.3 vs. 12 {+-} 0.4 and 11 {+-} 0.2, respectively). More {gamma}H2AX foci were observed in MDA-MB-468 and 231-H2N cells exposed to {sup 111}In-DTPA-hEGF (6 MBq/{mu}g) plus SAHA vs. {sup 111}In-DTPA-hEGF alone (11 {+-} 0.3 and 12 {+-} 0.7 vs. 9 {+-} 0.4 and 7 {+-} 0.3, respectively). 5-aza-2-deoxycytidine enhanced the DNA damage caused by IR and {sup 111}In-DTPA-hEGF. Clonogenic survival was reduced in MDA-MB-468 and 231-H2N cells after IR (6 Gy) plus SAHA (1 {mu}M) vs. IR alone (0.6% {+-} 0.01 and 0.3% {+-} 0.2 vs. 5.8% {+-} 0.2 and 2% {+-} 0.1, respectively) and after {sup 111}In-DTPA-hEGF plus SAHA compared to {sup 111}In-DTPA-hEGF alone (21% {+-} 0.4% and 19% {+-} 4.6 vs. 33% {+-} 2.3 and 32% {+-} 3.7). SAHA did not affect {sup 111}In-DTPA-hEGF nuclear localization. Hypertonic treatment resulted in fewer {gamma}H2AX foci per cell

  7. The Use of Auger Spectroscopy for the in situ Elemental Characterization of Sub-micrometer Presolar Grains

    Energy Technology Data Exchange (ETDEWEB)

    Stadermann, Frank J.; Floss, Christine; Bose, Maitrayee P.; Lea, Alan S.

    2009-10-01

    Presolar grains are small samples of stardust which can be found at low abundances in some of the most unaltered types of extraterrestrial materials. These grains condensed in the environments of massive stars before the formation of the solar system and survived incorporation into solar system materials without completely losing their isotopic, elemental and mineralogical makeup. Laboratory analyses of these presolar grains give insights into stellar nucleosynthesis and provide clues about the physical and chemical conditions during their formation as well as about interstellar exposure history and parent body processes. Since most presolar grains are less than 1 micrometer in diameter and represent only a few ppm of their host materials (e.g., meteorites or interplanetary dust particles), locating and studying these particles can be analytically challenging. Recently, we began using scanning Auger spectroscopy for the in situ elemental characterization of presolar grains and found that this technique, especially when paired with spatially matched NanoSIMS isotopic studies, can provide important insights that would be difficult to obtain with other analytical approaches. Here we discuss details of applying Auger spectroscopy to sub-micrometer sized geological samples and address practical issues such as sample preparation, measurement settings, data processing, and elemental quantification.

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

    Energy Technology Data Exchange (ETDEWEB)

    Rezaee, Mohammad, E-mail: Mohammad.Rezaee@USherbrooke.ca; Hunting, Darel J.; Sanche, Léon [Groupe en Sciences des Radiations, Département de Médecine Nucléaire et Radiobiologie, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, Québec J1H 5N4 (Canada)

    2014-07-15

    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{sup 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. Results: For a single decay of{sup 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{sup 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. Conclusions: Ultra-low-energy electrons (<18 eV) substantially contribute to the absorbed dose and to the molecular damage from Auger-electron emitting radionuclides; hence, they should

  9. Diffraction and holography with photoelectrons and Auger electrons: Some new directions

    Energy Technology Data Exchange (ETDEWEB)

    Fadley, C.S. (California Univ., Davis, CA (United States) Lawrence Berkeley Lab., CA (United States))

    1992-06-01

    The current status of photoelectron and Auger-electron diffraction is reviewed, with emphasis on new directions of activity. The use of forward scattering in the study of adsorbed molecules, epitaxial overlayers, and clean surfaces is one of the most developed applications, and one that will become more powerful as higher energy resolution and perhaps spin analysis are used to resolve emitters on the basis of chemical state, position at a surface, or magnetic state. The use of larger data sets spanning a considerable fraction of the solid angle above a surface will also much enhance the structural information available, for example, in the growth of epitaxial layers or nanostructures on surfaces. Detailed fitting of experimental data to theoretical calculations based upon either single scattering or multiple scattering should also provide more rich structural information, including such parameters as substrate interlayer relaxation. Surface phase transitions in which near-surface layers become highly disordered can also be studied, with results that are complementary to those from such techniques as low energy electron diffraction and medium energy ion scattering. Short-range magnetic order also can be probed by somehow resolving the spin of the outgoing electrons, e.g. by using multiplet-split core levels.

  10. 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...

  11. New trigger algorithm of the Auger fluorescence telescopes and validation of their single electron resolution; Neuer Triggeralgorithmus der Auger-Fluoreszenzteleskope und Validierung ihrer Ein-Elektron-Aufloesung

    Energy Technology Data Exchange (ETDEWEB)

    Asch, T.

    2005-12-15

    The Pierre Auger Observatory analyses air shower events of ultra high energy cosmic rays. For the first time the two detector techniques to measure Cherenkov and fluorescence light have been combined to detect primary particle with energies >10{sup 19}eV. The raw data rate, as measured by the telescope's electronics, is in the order of 9 Gigabyte per second. A multi level trigger system, which reduces the data systematically in several levels and complexities without rejecting important shower events, is necessary. The different trigger levels are realised in hardware as well as in software. A new ansatz for the first software trigger and its functionality is developed and discussed. The trigger is based on the so far not used information of the readout electronics. The resulting trigger level is more efficient and rejects sheet lightning better compared with present trigger level. Thus, the trigger rate to the next trigger level is decreased and the DAQ system is released. Different calibration methods, which are made regularly, are essential for an experiment. The results of different calibration methods have to be consistent to each other. The single electron resolution of the photomultiplier tubes play an important role in this context. The single electron resolution is a geometry and material dependent factor and up to now only known from Monte Carlo simulations. The experimental validation through direct measurement and the importance of the single electron resolution are discussed. The measurement was possible with small modifications of the configuration. The result of the single electron resolution is within its error in good agreement with the one known from Monte Carlo simulations. The low statistical error of 4% shows a low manufacturing tolerance, so that we can assume the resolution to be constant for the type of photomultiplier tubes used. (orig.)

  12. Block copolymer micelles target Auger electron radiotherapy to the nucleus of HER2-positive breast cancer cells.

    Science.gov (United States)

    Hoang, Bryan; Reilly, Raymond M; Allen, Christine

    2012-02-13

    Intracellular trafficking of Auger electron emitting radionuclides to perinuclear and nuclear regions of cells is critical to realizing their full therapeutic potential. In the present study, block copolymer micelles (BCMs) were labeled with the Auger electron emitter indium-111 ((111)In) and loaded with the radiosensitizer methotrexate. HER2 specific antibodies (trastuzumab fab) and nuclear localization signal (NLS; CGYGPKKKRKVGG) peptides were conjugated to the surface of the BCMs to direct uptake in HER2 expressing cells and subsequent localization in the cell nucleus. Cell uptake and intracellular distribution of the multifunctional BCMs were evaluated in a panel of breast cancer cell lines with different levels of HER2 expression. Indeed cell uptake was found to be HER2 density dependent, confirming receptor-mediated internalization of the BCMs. Importantly, conjugation of NLS peptides to the surface of BCMs was found to result in a significant increase in nuclear uptake of the radionuclide (111)In. Successful nuclear targeting was shown to improve the antipoliferative effect of the Auger electrons as measured by clonogenic assays. In addition, a significant radiation enhancement effect was observed by concurrent delivery of low-dose MTX and (111)In in all breast cancer cell lines evaluated.

  13. Electronic imaging and high spatial resolution slow electron spectroscopy

    International Nuclear Information System (INIS)

    Scanning electron microscopy and scanning Auger are now commonly used techniques. They are extended here to the complete electron energy distribution. It is shown that pictures can be obtained with electron energy loss peaks or with true secondary electron peaks of very low energy. These pictures are performed with very low primary electron energies (Esub(p) approximately 250 eV) and a fairly good spatial resolution. A very wide field of application of these techniques is now open. In the next future, work function and adsorbed hydrogen micromapping will be obtained

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

    International Nuclear Information System (INIS)

    Targeting of radiation damage to specific DNA sequences is the essence of antigene 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 125I with the sequence-specific action of triplex-forming oligonucleotides (TFO). TFO complementary to polypurine-polypyrimidine regions of human genes were synthesized and labeled with 125I-dCTP by the primer extension method. 125I-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 125I-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 125I with single-nucleotide resolution. It was showed that the designed 125I-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 125I-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 125I-TFO to target specific sequences in their natural environment - within eukaryotic nucleus. Repair of 125I-TFO-induced DNA damage should typically result in mutagenic gene inactivation

  15. 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.

  16. Specific energy from Auger and conversion electrons of 131I, 188Re-anti-CD20 to a lymphocyte's nucleus

    Science.gov (United States)

    Torres-García, E.; Carrillo-Cazares, T. A.

    2011-01-01

    The typical radionuclides used to label anti-CD20 in the treatment of non-Hodgkin's lymphoma are 90Y, 131I, and 188Re, with the emission of beta particles, Auger electrons, and conversion electrons for the latter two. The aim of the present work was to calculate the contribution of high linear energy transfer radiation as Auger electrons (AE) and conversion electrons (CE) of 131I and 188Re-anti-CD20 to mean specific energy into the cell nucleus by Monte Carlo simulation (MCS), so as to infer therapeutic effectiveness on a dosimetric basis. MCS was used to quantify the frequency-mean specific energy into the cell nucleus, where the cell was modeled by two concentric spheres, considering two cell models. The results showed that 10% and 33% of the mean-specific energies (z¯) per disintegration imparted to the cell nucleus for both geometries are due to AE and CE; on the other hand, if the hit of AE and CE occurs, the contribution to (z¯) is about 64% and 86% for 131I and 188Re, respectively. According to the amount of specific energy from AE and CE into the cell nucleus by positive event, they can cause catastrophic effects in the nuclear DNA in the treatment of non-Hodgkin's lymphoma with 131I, 188Re-anti-CD20.

  17. Ultra high vacuum scanning Auger/electron microscopy studies of oxidation and B surface segregation of in situ fractured B- doped Ni3Al alloys

    NARCIS (Netherlands)

    Agterveld, D.T.L. van; Koch, S.A.; Palasantzas, G.; Hosson, J.Th.M. De

    2001-01-01

    This paper focuses on local probe Auger spectroscopy studies of segregation and oxidation of in situ fractured Ni3Al specimens, both with and without B-doping. Although immediately after in situ fracture small amounts of segregated B at grain boundaries were observed occasionally in the B-doped spec

  18. 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.

    2016-05-17

    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.

  19. Accelerator based Production of Auger-Electron-emitting Isotopes for Radionuclide Therapy

    DEFF Research Database (Denmark)

    Thisgaard, Helge

    In this research project the focus has been on the identification and production of new, unconventional Augerelectron- emitting isotopes for targeted radionuclide therapy of cancer. Based on 1st principles dosimetry calculations on the subcellular level, the Augeremitter 119Sb has been identified...... 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...

  20. Proceedings of the 5. seminar on electron spetroscopy of socialist countries

    International Nuclear Information System (INIS)

    Instrumental, experimental, and theoretical aspects of electron spectroscopy as well as their applications to solve problems arising in surface physics and surface chemistry have been discussed. 94 synopses on photoelectron spectroscopy (XPS and UPS), Auger electron spectroscopy, electron energy loss spectroscopy, appearance potential spectroscopy, low-energy electron diffraction, reflection of high-energy electron diffraction, and secondary ion mass spectroscopy are included

  1. Localized Irradiation of Cell Membrane by Auger Electrons Is Cytotoxic Through Oxidative Stress-Mediated Nontargeted Effects

    Science.gov (United States)

    Paillas, Salomé; Ladjohounlou, Riad; Lozza, Catherine; Pichard, Alexandre; Boudousq, Vincent; Jarlier, Marta; Sevestre, Samuel; Le Blay, Marion; Deshayes, Emmanuel; Sosabowski, Jane; Chardès, Thierry; Navarro-Teulon, Isabelle; Mairs, Robert J.

    2016-01-01

    Abstract Aims: We investigated whether radiation-induced nontargeted effects are involved in the cytotoxic effects of anticell surface monoclonal antibodies labeled with Auger electron emitters, such as iodine 125 (monoclonal antibodies labeled with 125I [125I-mAbs]). Results: We showed that the cytotoxicity of 125I-mAbs targeting the cell membrane of p53+/+ HCT116 colon cancer cells is mainly due to nontargeted effects. Targeted and nontargeted cytotoxicities were inhibited in vitro following lipid raft disruption with Methyl-β-cyclodextrin (MBCD) or filipin or use of radical oxygen species scavengers. 125I-mAb efficacy was associated with acid sphingomyelinase activation and modulated through activation of the AKT, extracellular signal-related kinase ½ (ERK1/2), p38 kinase, c-Jun N-terminal kinase (JNK) signaling pathways, and also of phospholipase C-γ (PLC-γ), proline-rich tyrosine kinase 2 (PYK-2), and paxillin, involved in Ca2+ fluxes. Moreover, the nontargeted response induced by directing 5-[(125)I]iodo-2′-deoxyuridine to the nucleus was comparable to that of 125I-mAb against cell surface receptors. In vivo, we found that the statistical significance of tumor growth delay induced by 125I-mAb was removed after MBCD treatment and observed oxidative DNA damage beyond the expected Auger electron range. These results suggest the involvement of nontargeted effects in vivo also. Innovation: Low-energy Auger electrons, such as those emitted by 125I, have a short tissue range and are usually targeted to the nucleus to maximize their cytotoxicity. In this study, we show that targeting the cancer cell surface with 125I-mAbs produces a lipid raft-mediated nontargeted response that compensates for the inferior efficacy of non-nuclear targeting. Conclusion: Our findings describe the mechanisms involved in the efficacy of 125I-mAbs targeting the cancer cell surface. Antioxid. Redox Signal. 25, 467–484. PMID:27224059

  2. 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.

  3. Evaluation of new iodinated acridine derivatives for targeted radionuclide therapy of melanoma using 125I, an Auger electron emitter

    International Nuclear Information System (INIS)

    The full text of the publication follows. The increasing incidence of melanoma and the lack of effective therapy on the disseminated form have led to an urgent need for new specific therapies. Several iodo-benzamides or analogs are known to possess specific affinity for melanoma tissue. New hetero-aromatic derivatives have been designed with a cytotoxic moiety and termed DNA intercalating agents. These compounds could be applied in targeted radionuclide therapy using 125I, Auger electrons emitter which gives high-energetic localized irradiation. Two iodinated acridine derivatives have been reported to present an in vivo kinetic profile conducive to application in targeted radionuclide therapy. The aim of the present study was to perform a preclinical evaluation of these compounds. The DNA intercalating property was confirmed for both compounds. After radiolabeling with 125I, the two compounds induced in vitro a significant radiotoxicity on B16F0 melanoma cells. The acridine compound, ICF01040, appeared more radio toxic than the acridone compound, ICF01035. While cellular uptake was similar for both compounds, SIMS analysis and in vitro protocol showed a stronger affinity for melanin with ICF01035, which was able to induce a predominant scavenging process in the melanosome and restrict access to the nucleus. Nevertheless, an important radiotoxicity was measured for the two compounds while the nuclear accumulation was low. Indeed, even if nuclear localization remains the main target sensitive to Auger electrons, the cell membrane remains sensitive to 125I decays. So, these compounds may induce secondary toxic effects of irradiation, such as membrane lipid damage. Conducted to current experiments are evaluate such hypothesis. Taken together, these results suggest that ICF01040 is a better candidate for application in targeted radionuclide therapy using 125I. The next step will be in vivo evaluation, where high tumoral vectorization gives promising perspectives

  4. 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.

  5. X-ray Photoelectron Spectroscopy Database (Version 4.1)

    Science.gov (United States)

    SRD 20 X-ray Photoelectron Spectroscopy Database (Version 4.1) (Web, free access)   The NIST XPS Database gives access to energies of many photoelectron and Auger-electron spectral lines. The database contains over 22,000 line positions, chemical shifts, doublet splittings, and energy separations of photoelectron and Auger-electron lines.

  6. Narrow electron injector for ballistic electron spectroscopy

    International Nuclear Information System (INIS)

    A three-terminal hot electron transistor is used to measure the normal energy distribution of ballistic electrons generated by an electron injector utilizing an improved injector design. A triple barrier resonant tunneling diode with a rectangular transmission function acts as a narrow (1 meV) energy filter. An asymmetric energy distribution with its maximum on the high-energy side with a full width at half maximum of ΔEinj=10 meV is derived. [copyright] 2001 American Institute of Physics

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

    Science.gov (United States)

    Videla, M.; Platino, M.; García, B.; Almela, A.; de la Vega, G.; Lucero, A.; Suarez, F.; Wainberg, O.; Sanchez, F.; Yelos, D.

    2015-08-01

    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 m2 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.

  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. Spherical electrostatic electron spectrometer for Moessbauer spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Benczer-Koller, N.; Kolk, B.

    1977-01-01

    A high transmission spherical electrostatic electron spectrometer was constructed for combined Moessbauer and conversion electron spectroscopies. To date, a transmission of 7% and an energy resolution of 2.5% at 14 keV were achieved for a source of 1 cm diameter.

  11. In-trap conversion electron spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Weissman, L. E-mail: weissman@nscl.msu.edu; Ames, F.; Aeysto, J.; Forstner, O.; Reisinger, K.; Rinta-Antila, S

    2002-10-21

    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 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. 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.

  13. Dependence of Cell Survival on Iododeoxyuridine Concentration in 35-keV Photon-Activated Auger Electron Radiotherapy

    International Nuclear Information System (INIS)

    Purpose: To measure and compare Chinese hamster ovary cell survival curves using monochromatic 35-keV photons and 4-MV x-rays as a function of concentration of the radiosensitizer iododeoxyuridine (IUdR). Methods and Materials: IUdR was incorporated into Chinese hamster ovary cell DNA at 16.6 ± 1.9%, 12.0 ± 1.4%, and 9.2 ± 1.3% thymidine replacement. Cells were irradiated from 1 to 8 Gy with 35-keV synchrotron-generated photons and conventional radiotherapy 4-MV x-rays. The effects of the radiation were measured via clonogenic survival assays. Surviving fraction was plotted vs. dose and fit to a linear quadratic model. Sensitization enhancement ratios (SER10) were calculated as the ratio of doses required to achieve 10% surviving fraction for cells without and with DNA-incorporated IUdR. Results: At 4 MV, SER10 values were 2.6 ± 0.1, 2.2 ± 0.1, and 1.5 ± 0.1 for 16.6%, 12.0%, and 9.2% thymidine replacement, respectively. At 35 keV, SER10 values were 4.1 ± 0.2, 3.0 ± 0.1, and 2.0 ± 0.1, respectively, which yielded SER10 ratios (35 keV:4 MV) of 1.6 ± 0.1, 1.4 ± 0.1, and 1.3 ± 0.1, respectively. Conclusions: SER10 increases monotonically with percent thymidine replacement by IUdR for both modalities. As compared to 4-MV x-rays, 35-keV photons produce enhanced SER10 values whose ratios are linear with percent thymidine replacement and assumed to be due to Auger electrons contributing to enhanced dose to DNA. Although this Auger effectiveness factor is less than the radiosensitization factor of IUdR, both could be important for the clinical efficacy of IUdR radiotherapy.

  14. Evaluation of new iodinated acridine derivatives for targeted radionuclide therapy of melanoma using 125I, an Auger electron emitter.

    Science.gov (United States)

    Gardette, Maryline; Papon, Janine; Bonnet, Mathilde; Desbois, Nicolas; Labarre, Pierre; Wu, Ting-Dee; Miot-Noirault, Elisabeth; Madelmont, Jean-Claude; Guerquin-Kern, Jean-Luc; Chezal, Jean-Michel; Moins, Nicole

    2011-12-01

    The increasing incidence of melanoma and the lack of effective therapy on the disseminated form have led to an urgent need for new specific therapies. Several iodobenzamides or analogs are known to possess specific affinity for melanoma tissue. New heteroaromatic derivatives have been designed with a cytotoxic moiety and termed DNA intercalating agents. These compounds could be applied in targeted radionuclide therapy using (125)I, which emits Auger electrons and gives high-energy, localized irradiation. Two iodinated acridine derivatives have been reported to present an in vivo kinetic profile conducive to application in targeted radionuclide therapy. The aim of the present study was to perform a preclinical evaluation of these compounds. The DNA intercalating property was confirmed for both compounds. After radiolabeling with (125)I, the two compounds induced in vitro a significant radiotoxicity to B16F0 melanoma cells. Nevertheless, the acridine compound appeared more radiotoxic than the acridone compound. While cellular uptake was similar for both compounds, SIMS analysis and in vitro protocol showed a stronger affinity for melanin with acridone derivative, which was able to induce a predominant scavenging process in the melanosome and restrict access to the nucleus. In conclusion, the acridine derivative with a higher nuclear localization appeared a better candidate for application in targeted radionuclide therapy using (125)I. PMID:20567996

  15. Electron spectroscopy of collisional excited atoms

    International Nuclear Information System (INIS)

    In this thesis measurements are described in which coincidences are detected between scattered projectiles and emitted electrons. This yields information on two-electron excitation processes. In order to show what can be learnt from coincidence experiments a detailed theoretical analysis is given. The transition amplitudes, which contain all the information, are introduced (ch.2). In ch.3 the experimental set-up is shown. The results for the Li+-He system are shown in ch. 7 and are compared with predictions based on the Molecular-Orbitalmodel which however does not account for two-excitation mechanisms. With the transition amplitudes also the wave function of the excited atom has been completely determined. In ch.8 the shape of the electron cloud, induced by the collision, is derived from the amplitudes. The relation between the oscillatory motion of this cloud after the collision and the correlation between the two electrons of the excited atom is discussed. In ch. 6 it is shown that the broad structures in the non-coincident energy spectra of the Li+-He system are erroneously interpretated as a result of electron emission from the (Li-He)+-quasimolecule. A model is presented which explains, based on the results obtained from the coincidence measurements, these broad structures. In ch. 4 the Post-Collision Interaction process is treated. It is shown that for high-energy collisions, in contrast with general assumptions, PCI is important. In ch. 5 the importance of PCI-processes in photoionization of atoms, followed by Auger decay, are studied. From the formulas derived in ch. 4 simple analytical results are obtained. These are applied to recent experiments and good agreement is achieved. 140 refs.; 55 figs.; 9 tabs

  16. Dynamical effects in electron spectroscopy

    Science.gov (United States)

    Zhou, Jianqiang Sky; Kas, J. J.; Sponza, Lorenzo; Reshetnyak, Igor; Guzzo, Matteo; Giorgetti, Christine; Gatti, Matteo; Sottile, Francesco; Rehr, J. J.; Reining, Lucia

    2015-11-01

    One of the big challenges of theoretical condensed-matter physics is the description, understanding, and prediction of the effects of the Coulomb interaction on materials properties. In electronic spectra, the Coulomb interaction causes a renormalization of energies and change of spectral weight. Most importantly, it can lead to new structures, often called satellites. These can be linked to the coupling of excitations, also termed dynamical effects. State-of-the-art methods in the framework of many-body perturbation theory, in particular, the widely used GW approximation, often fail to describe satellite spectra. Instead, approaches based on a picture of electron-boson coupling such as the cumulant expansion are promising for the description of plasmon satellites. In this work, we give a unified derivation of the GW approximation and the cumulant expansion for the one-body Green's function. Using the example of bulk sodium, we compare the resulting spectral functions both in the valence and in the core region, and we discuss the dispersion of quasi-particles and satellites. We show that self-consistency is crucial to obtain meaningful results, in particular, at large binding energies. Very good agreement with experiment is obtained when the intrinsic spectral function is corrected for extrinsic and interference effects. Finally, we sketch how one can approach the problem in the case of the two-body Green's function, and we discuss the cancellation of various dynamical effects that occur in that case.

  17. Dynamical effects in electron spectroscopy.

    Science.gov (United States)

    Zhou, Jianqiang Sky; Kas, J J; Sponza, Lorenzo; Reshetnyak, Igor; Guzzo, Matteo; Giorgetti, Christine; Gatti, Matteo; Sottile, Francesco; Rehr, J J; Reining, Lucia

    2015-11-14

    One of the big challenges of theoretical condensed-matter physics is the description, understanding, and prediction of the effects of the Coulomb interaction on materials properties. In electronic spectra, the Coulomb interaction causes a renormalization of energies and change of spectral weight. Most importantly, it can lead to new structures, often called satellites. These can be linked to the coupling of excitations, also termed dynamical effects. State-of-the-art methods in the framework of many-body perturbation theory, in particular, the widely used GW approximation, often fail to describe satellite spectra. Instead, approaches based on a picture of electron-boson coupling such as the cumulant expansion are promising for the description of plasmon satellites. In this work, we give a unified derivation of the GW approximation and the cumulant expansion for the one-body Green's function. Using the example of bulk sodium, we compare the resulting spectral functions both in the valence and in the core region, and we discuss the dispersion of quasi-particles and satellites. We show that self-consistency is crucial to obtain meaningful results, in particular, at large binding energies. Very good agreement with experiment is obtained when the intrinsic spectral function is corrected for extrinsic and interference effects. Finally, we sketch how one can approach the problem in the case of the two-body Green's function, and we discuss the cancellation of various dynamical effects that occur in that case. PMID:26567648

  18. Dynamical effects in electron spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Jianqiang Sky, E-mail: jianqiang.zhou@polytechnique.edu; Reshetnyak, Igor; Giorgetti, Christine; Sottile, Francesco; Reining, Lucia [Laboratoire des Solides Irradiés, École Polytechnique, CNRS, CEA-DSM-IRAMIS, Université Paris-Saclay, F-91128 Palaiseau (France); Kas, J. J.; Rehr, J. J. [Department of Physics, University of Washington, Seattle, Washington 98195-1560 (United States); Sponza, Lorenzo [Department of Physics, King’s College London, London WC2R 2LS (United Kingdom); Guzzo, Matteo [Institut für Physik und IRIS Adlershof, Humboldt-Universität zu Berlin, D-12489 Berlin (Germany); Gatti, Matteo [Laboratoire des Solides Irradiés, École Polytechnique, CNRS, CEA-DSM-IRAMIS, Université Paris-Saclay, F-91128 Palaiseau (France); Synchrotron SOLEIL, L’Orme des Merisiers, Saint-Aubin, BP 48, F-91192 Gif-sur-Yvette (France)

    2015-11-14

    One of the big challenges of theoretical condensed-matter physics is the description, understanding, and prediction of the effects of the Coulomb interaction on materials properties. In electronic spectra, the Coulomb interaction causes a renormalization of energies and change of spectral weight. Most importantly, it can lead to new structures, often called satellites. These can be linked to the coupling of excitations, also termed dynamical effects. State-of-the-art methods in the framework of many-body perturbation theory, in particular, the widely used GW approximation, often fail to describe satellite spectra. Instead, approaches based on a picture of electron-boson coupling such as the cumulant expansion are promising for the description of plasmon satellites. In this work, we give a unified derivation of the GW approximation and the cumulant expansion for the one-body Green’s function. Using the example of bulk sodium, we compare the resulting spectral functions both in the valence and in the core region, and we discuss the dispersion of quasi-particles and satellites. We show that self-consistency is crucial to obtain meaningful results, in particular, at large binding energies. Very good agreement with experiment is obtained when the intrinsic spectral function is corrected for extrinsic and interference effects. Finally, we sketch how one can approach the problem in the case of the two-body Green’s function, and we discuss the cancellation of various dynamical effects that occur in that case.

  19. Proximity Scanning Transmission Electron Microscopy/Spectroscopy

    CERN Document Server

    Hwang, Ing-Shouh

    2016-01-01

    Here a new microscopic method is proposed to image and characterize very thin samples like few-layer materials, organic molecules, and nanostructures with nanometer or sub-nanometer resolution using electron beams of energies lower than 20 eV. The microscopic technique achieves high resolution through the proximity (or near-field) effect, as in scanning tunneling microscopy (STM), while it also allows detection of transmitted electrons for imaging and spectroscopy, as in scanning transmission electron microscopy (STEM). This proximity transmission electron microscopy (PSTEM) does not require any lens to focus the electron beam. It also allows detailed characterization of the interaction of low-energy electron with materials. PSTEM can operate in a way very similar to scanning tunneling microscopy, which provides high-resolution imaging of geometric and electronic structures of the sample surface. In addition, it allows imaging and characterization of the interior structures of the sample based on the detected...

  20. Determination of the inelastic mean free path of electrons in polythiophenes using elastic peak electron spectroscopy method

    Science.gov (United States)

    Lesiak, B.; Kosinski, A.; Jablonski, A.; Kövér, L.; Tóth, J.; Varga, D.; Cserny, I.; Zagorska, M.; Kulszewicz-Bajer, I.; Gergely, G.

    2001-04-01

    The inelastic mean free path (IMFP) is an important parameter for quantitative surface characterisation by Auger electron spectroscopy, X-ray photoelectron spectroscopy or electron energy loss spectroscopy. An extensive database of the IMFPs for selected elements, inorganic and organic compounds has been recently published by Powell and Jablonski. As it follows from this compilation, the published material on IMFPs for conductive polymers is very limited. Selected polymers, such as polyacetylenes and polyanilines, have been investigated only recently. The present study is a continuation of the research on IMFPs determination in conductive polymers using the elastic peak electron spectroscopy (EPES) method. In the present study three polythiophene samples have been studied using high energy resolution spectrometer and two standards: Ni and Ag. The resulting experimental IMFPs are compared to the respective IMFP values determined using the predictive formulae proposed by Tanuma and Powell (TPP-2M) and by Gries (G1), showing a good agreement. The scatter between the experimental and predicted IMFPs in polythiophenes is evaluated. The statistical and systematic errors, their sources and the possible contributions to the systematic error due to influence of the accuracy of the input parameters, such as the surface composition and density, on the IMFPs derived from the experiments and Monte Carlo calculations, are extensively discussed.

  1. Evaluation of two (125)I-radiolabeled acridine derivatives for Auger-electron radionuclide therapy of melanoma.

    Science.gov (United States)

    Gardette, Maryline; Viallard, Claire; Paillas, Salomé; Guerquin-Kern, Jean-Luc; Papon, Janine; Moins, Nicole; Labarre, Pierre; Desbois, Nicolas; Wong-Wah-Chung, Pascal; Palle, Sabine; Wu, Ting-Di; Pouget, Jean-Pierre; Miot-Noirault, Elisabeth; Chezal, Jean-Michel; Degoul, Francoise

    2014-08-01

    We previously selected two melanin-targeting radioligands [(125)I]ICF01035 and [(125)I]ICF01040 for melanoma-targeted (125)I radionuclide therapy according to their pharmacological profile in mice bearing B16F0 tumors. Here we demonstrate in vitro that these compounds present different radiotoxicities in relation to melanin and acidic vesicle contents in B16F0, B16F0 PTU and A375 cell lines. ICF01035 is effectively observed in nuclei of achromic (A375) melanoma or in melanosomes of melanized melanoma (B16F0), while ICF01040 stays in cytoplasmic vesicles in both cells. [(125)I]ICF01035 induced a similar survival fraction (A50) in all cell lines and led to a significant decrease in S-phase cells in amelanotic cell lines. [(125)I]ICF01040 induced a higher A50 in B16 cell lines compared to [(125)I]ICF01035 ones. [(125)I]ICF01040 induced a G2/M blockade in both A375 and B16F0 PTU, associated with its presence in cytoplasmic acidic vesicles. These results suggest that the radiotoxicity of [(125)I]ICF01035 and [(125)I]ICF01040 are not exclusively reliant on DNA alterations compatible with γ rays but likely result from local dose deposition (Auger electrons) leading to toxic compound leaks from acidic vesicles. In vivo, [(125)I]ICF01035 significantly reduced the number of B16F0 lung colonies, enabling a significant increase in survival of the treated mice. Targeting melanosomes or acidic vesicles is thus an option for future melanoma therapy. PMID:24691673

  2. The electronic paramagnetic resonance spectroscopy - Applications

    International Nuclear Information System (INIS)

    This collective book addresses the various applications of electronic paramagnetic resonance (EPR) spectroscopy. The addressed issues (and chapters) are: the dosimetry of ionizing radiation, the tracing of natural organic matter within drainage basins, the detection and characterisation of free radicals after spin trapping, copper complexation by peptides involved in neuro-degenerative diseases, crystal chemistry of clay minerals and alteration process and evolution of continental surfaces, structure and catalytic mechanism of redox enzymes, the primitive carbonated matter, use of paramagnetic probes to study structural transitions within proteins, organic radicals and molecular magnetism, EPR of transient magnetic species, characterization of contrast agents for magnetic resonance imaging, and fundamentals and applications of ferromagnetic resonance spectroscopy. Appendices present the principles of magnetic resonance (Bloch equations and pulse methods), the pulse EPR (ESEEM, HYSCORE and PELDOR experiments), the principle of continuous wave ENDOR (Electron-nuclear double resonance) spectroscopy, and the protein functions

  3. Auger electron spectra in 5.5 MeV/amu Nesup(q+) and Arsup(q+) ion impact on Ne

    International Nuclear Information System (INIS)

    A study of Ne K-Auger spectra induced by 5.5 MeV/amu Ne3+, Ne10+, Ar6+ and Ar17+ heavy ions on Ne is presented. Some average quantities (the centroid energy of KLL Auger spectra, the average number of L vacancies produced simultaneously with the K vacancy, the effective charge of the projectile in the actual process, Zsub(eff), the satellite to total intensity ratio) characterizing the KLsup(n) ionization process have been extracted from these spectra. Relative K-shell ionization cross sections and KLM to KLL cross section ratios have also been evaluated. The deduced experimental Zsub(eff) values have been compared to the results of plane wave Born approximation (PWBA) and binary encounter approximation (BEA) calculations. A simple model calculat on is made in an attempt to nterpret the variation of the probability for the ejection of an L-shell electron (Psub(L)) as a function of Zsub(eff)/vsub(p). Some statements regarding individual lines and groups in the Auger spectra are made

  4. Photoelectron recapture and reemission process associated with double Auger decay in Ar

    Science.gov (United States)

    Hikosaka, Y.; Mashiko, R.; Odagiri, T.; Adachi, J.; Tanaka, H.; Kosuge, T.; Ito, K.

    2016-06-01

    Multielectron coincidence spectroscopy has been performed for Ar at a photon energy of only 0.2 eV above the 2 p1 /2 threshold. It is revealed that a postcollision interaction induced by double Auger decay leads to photoelectron recapture, followed by reemission of the captured electron, where the recapture of the slow photoelectron forms the A r2 + Rydberg-excited states which subsequently undergo autoionization. The energy correlation of the emitted electrons discloses that both direct and cascade paths in the double Auger decay contribute to the photoelectron recapture.

  5. Two-dimensional vibrational-electronic spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Courtney, Trevor L.; Fox, Zachary W.; Slenkamp, Karla M.; Khalil, Munira, E-mail: mkhalil@uw.edu [Department of Chemistry, University of Washington, Box 351700, Seattle, Washington 98195 (United States)

    2015-10-21

    Two-dimensional vibrational-electronic (2D VE) spectroscopy is a femtosecond Fourier transform (FT) third-order nonlinear technique that creates a link between existing 2D FT spectroscopies in the vibrational and electronic regions of the spectrum. 2D VE spectroscopy enables a direct measurement of infrared (IR) and electronic dipole moment cross terms by utilizing mid-IR pump and optical probe fields that are resonant with vibrational and electronic transitions, respectively, in a sample of interest. We detail this newly developed 2D VE spectroscopy experiment and outline the information contained in a 2D VE spectrum. We then use this technique and its single-pump counterpart (1D VE) to probe the vibrational-electronic couplings between high frequency cyanide stretching vibrations (ν{sub CN}) and either a ligand-to-metal charge transfer transition ([Fe{sup III}(CN){sub 6}]{sup 3−} dissolved in formamide) or a metal-to-metal charge transfer (MMCT) transition ([(CN){sub 5}Fe{sup II}CNRu{sup III}(NH{sub 3}){sub 5}]{sup −} dissolved in formamide). The 2D VE spectra of both molecules reveal peaks resulting from coupled high- and low-frequency vibrational modes to the charge transfer transition. The time-evolving amplitudes and positions of the peaks in the 2D VE spectra report on coherent and incoherent vibrational energy transfer dynamics among the coupled vibrational modes and the charge transfer transition. The selectivity of 2D VE spectroscopy to vibronic processes is evidenced from the selective coupling of specific ν{sub CN} modes to the MMCT transition in the mixed valence complex. The lineshapes in 2D VE spectra report on the correlation of the frequency fluctuations between the coupled vibrational and electronic frequencies in the mixed valence complex which has a time scale of 1 ps. The details and results of this study confirm the versatility of 2D VE spectroscopy and its applicability to probe how vibrations modulate charge and energy transfer in a

  6. 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.

  7. The chemical structure of the ZnO/SiC heterointerface as revealed by electron spectroscopies

    International Nuclear Information System (INIS)

    ZnO layers were deposited on 6H-SiC single crystalline wafers by radio frequency magnetron sputtering. The chemical structure of the ZnO/SiC interface was studied by x-ray photoelectron and x-ray excited Auger electron spectroscopy. A complex chemical structure, involving not only silicon–carbon and zinc–oxygen bonds but also silicon–oxygen and zinc–silicon–oxygen bonds was revealed to form at the ZnO/SiC interface. Based on the comparison with the presumably inert (i.e. chemically abrupt) ZnO/Mo interface, it was concluded that a willemite-like zinc silicate (i.e. Zn2SiO4) interface species develops between ZnO and SiC. The presence of this species at the ZnO/SiC interface will affect the electronic structure of the heterojunction and thus needs to be considered for device optimization. (paper)

  8. 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...

  9. New insight into the Auger decay process in O{sub 2}: The coincidence perspective

    Energy Technology Data Exchange (ETDEWEB)

    Arion, Tiberiu, E-mail: tiberiu.arion@cfel.de [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, Boltzmannstr. 2, 85748 Garching (Germany); Institut fuer Experimentalphysik, Universitaet Hamburg, Luruper Chaussee 149, 22761 Hamburg (Germany); Puettner, Ralph [Institut fuer Experimentalphysik, Freie Universitaet Berlin, Arnimallee 14, 14195 Berlin (Germany); Lupulescu, Cosmin [Technische Universitaet Berlin, Institut fuer Optik und atomare Physik, Hardenbergstr. 36, 10623 Berlin (Germany); Ovsyannikov, Ruslan [Helmholtz-Zentrum Berlin, Albert-Einstein-Str. 15, 12489 Berlin (Germany); Foerstel, Marko [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, Boltzmannstr. 2, 85748 Garching (Germany); Oehrwall, Gunnar [MAX-lab, Lund University, P.O. Box 118, SE-22100 Lund (Sweden); Lindblad, Andreas [Uppsala University, Department of Physics and Astronomy, Box 516, SE-751 20 Uppsala (Sweden); Ueda, Kiyoshi [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577 (Japan); Svensson, Svante [Uppsala University, Department of Physics and Astronomy, Box 516, SE-751 20 Uppsala (Sweden); Bradshaw, Alex M. [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, Boltzmannstr. 2, 85748 Garching (Germany); Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin (Germany); Eberhardt, Wolfgang [Technische Universitaet Berlin, Institut fuer Optik und atomare Physik, Hardenbergstr. 36, 10623 Berlin (Germany); Center for Free-Electron Laser Science, Notkestrasse 85, 22607 Hamburg (Germany); and others

    2012-09-15

    Highlights: Black-Right-Pointing-Pointer We developed a new experimental set-up for e,e-coincidence experiments. Black-Right-Pointing-Pointer New information on the potential curves of the final states in O{sub 2} has been extracted. Black-Right-Pointing-Pointer We observed new features, assigned to autoionization of neutral doubly excited states. -- Abstract: Photoelectron-Auger electron coincidence spectroscopy is a powerful tool for the investigation of Auger decay processes with different core-ionized intermediate states. In this paper we describe an investigation into the Auger decay of the O{sub 2} molecule, with the purpose of bringing new insight into the dynamics of the core hole decay mechanism. Using a novel experimental approach to measuring such coincidence spectra we report the highest resolution Auger spectrum of O{sub 2} recorded hitherto. In our approach, we have combined the advantages of these coincidence spectra with the high resolution and excellent signal-to-noise ratios of non-coincident Auger spectra and a state-of-the-art fit analysis. In this way we have derived information about the potential energy curves of the final states W {sup 3}{Delta}{sub u}, B {sup 3}{Pi}{sub g}, and B Prime {sup 3}{Sigma}{sub u}{sup -} and concluded that the corresponding Auger transitions are formed to a large part by strongly overlapping vibrational progressions. The present findings are compared to earlier results reported in the literature confirming some theoretical predictions.

  10. Temperature effects on Li4Ti5O12 electrode/electrolyte interfaces at the first cycle: A X-ray Photoelectron Spectroscopy and Scanning Auger Microscopy study

    Science.gov (United States)

    Gieu, J.-B.; Courrèges, C.; El Ouatani, L.; Tessier, C.; Martinez, H.

    2016-06-01

    Li4Ti5O12-based negative electrodes for Lithium-ion batteries are of interest because of the high reversibility of Li+ insertion/extraction. In this study, the surface of cycled electrodes is analysed by X-ray Photoelectron Spectroscopy (XPS) and Scanning Auger Microscopy (SAM) to investigate the effects of cycling temperature (room temperature, 60 °C and 85 °C) upon the solid electrolyte interphase (SEI) formation, which plays a major role in batteries electrochemical performances. Half-cells, with a vinylene carbonate containing electrolyte, are galvanostatically cycled at different steps of the first cycle: the mid-plateau during the first discharge, the end of the first discharge at 1.2 V and the end of the first charge at 2.0 V. XPS analysis evidences that higher temperatures promote the formation of a thicker SEI, which can explain the increase of the irreversible capacity with temperature. SAM mappings (allowing high spatial resolution ∼10-100 nm) evidence that this SEI homogeneously covers the electrode surface, regardless of the cycling temperature. During charge, the SEI is partially dissolved at room temperature, more slightly at 60 °C whereas at 85 °C, no clear evidence of layer thinning is observed. The SEI chemical composition is also investigated and reveals a majority of organic species and an increasing proportion of LiF with the temperature.

  11. 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.

  12. Étude par spectrométrie auger d'alliages aluminium-cuivre liquides

    Science.gov (United States)

    Laty, P.; Joud, J. C.; Desré, P.

    1981-03-01

    Surface analysis of liquid aluminium and aluminium-copper alloys have been performed by Auger electron spectroscopy at 775°C. Experiments were carried out, in UHV chamber, on liquid droplets located in graphite crucible heated by a heat pipe. Pure aluminium has been studied in view to estimate surface contamination. For each Al-Cu alloy surface composition is calculated from the Auger spectra. Peak to peak height ratios are deduced from limited extrapolation t zero level contamination. The deduced Al enrichment of the surface is compared with thermodynamical computation based on statistical model or Gibbs' adsorption relation.

  13. 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

  14. Stimulated excitation electron microscopy and spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Howie, A.

    2015-04-15

    Recent advances in instrumentation for electron optics and spectroscopy have prompted exploration of ultra-low excitations such as phonons, bond vibrations and Johnson noise. These can be excited not just with fast electrons but also thermally or by other external sources of radiation. The near-field theory of electron energy loss and gain provides a convenient platform for analysing these processes. Possibilities for selected phonon mapping and imaging are discussed. Effects should certainly be observable in atomic resolution structure imaging but diffraction contrast imaging could perhaps be more informative. Additional exciting prospects to be explored include the transition from phonon excitation to single atom recoil and the boosting of energy loss and gain signals with tuned laser illumination. - Highlights: • Electron energy gains and losses measure thermal or laser boosting of excitations. • Electron energy gains and losses are conveniently analysed by near field theory. • Diffraction contrast theory is relevant for phonon imaging by electrons. • The transition from phonon excitation to single atom recoil deserves study.

  15. Multidimensional Electronic Spectroscopy of Photochemical Reactions.

    Science.gov (United States)

    Nuernberger, Patrick; Ruetzel, Stefan; Brixner, Tobias

    2015-09-21

    Coherent multidimensional electronic spectroscopy can be employed to unravel various channels in molecular chemical reactions. This approach is thus not limited to analysis of energy transfer or charge transfer (i.e. processes from photophysics), but can also be employed in situations where the investigated system undergoes permanent structural changes (i.e. in photochemistry). Photochemical model reactions are discussed by using the example of merocyanine/spiropyran-based molecular switches, which show a rich variety of reaction channels, in particular ring opening and ring closing, cis-trans isomerization, coherent vibrational wave-packet motion, radical ion formation, and population relaxation. Using pump-probe, pump-repump-probe, coherent two-dimensional and three-dimensional, triggered-exchange 2D, and quantum-control spectroscopy, we gain intuitive pictures on which product emerges from which reactant and which reactive molecular modes are associated. PMID:26382095

  16. 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.

  17. Implementation of the Electron conversion Moessbauer spectroscopy

    International Nuclear Information System (INIS)

    In the present work has been exposed the principles of the Conversion Moessbauer Electron Spectroscopy and its possibilities of application. Is also described the operation of the parallel plate avalanche detector made at the CEADEN starting from modifications done to the Gancedo's model and is exposed examples of the use of this detector in the characterization of corroded surfaces, with chemical cleaning and in samples of welded joints. The experiences obtained of this work were extended to the National Polytechnic Institute of Mexico where a similar detector, made in our center, was installed there

  18. Electron spectroscopy analysis of contact surfaces in the wear of carbon brushes against copper commutators

    Science.gov (United States)

    Savage, D. E.; Lagally, M. G.; Schrader, M. E.

    Carbon brushes and copper commutator strips have been analyzed by a combination of techniques to investigate possible surface-related phenomena in the excessive wear of carbon brushes in motors and generators. X-ray photoelectron spectroscopy, scanning Auger microscopy, optical microscopy, scanning electron microscopy, and energy-dispersive X-ray analysis were used in this study. A thin SiO 2 film, of the order of 30 Å on the brushes, and of the order of several hundred Å on the commutators, was correlated with high wear and is believed to be the chief cause of the excessive wear. Possible models for the effect of SiO 2 on carbon brush wear are discussed.

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

    Science.gov (United States)

    Incerti, S.; Suerfu, B.; Xu, J.; Ivantchenko, V.; Mantero, A.; Brown, J. M. C.; Bernal, M. A.; Francis, Z.; Karamitros, M.; Tran, H. N.

    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.

  20. Auger Emitting Radiopharmaceuticals for Cancer Therapy

    Science.gov (United States)

    Falzone, Nadia; Cornelissen, Bart; Vallis, Katherine A.

    Radionuclides that emit Auger electrons have been of particular interest as therapeutic agents. This is primarily due to the short range in tissue, controlled linear paths and high linear energy transfer of these particles. Taking into consideration that ionizations are clustered within several cubic nanometers around the point of decay the possibility of incorporating an Auger emitter in close proximity to the cancer cell DNA has immense therapeutic potential thus making nuclear targeted Auger-electron emitters ideal for precise targeting of cancer cells. Furthermore, many Auger-electron emitters also emit γ-radiation, this property makes Auger emitting radionuclides a very attractive option as therapeutic and diagnostic agents in the molecular imaging and management of tumors. The first requirement for the delivery of Auger emitting nuclides is the definition of suitable tumor-selective delivery vehicles to avoid normal tissue toxicity. One of the main challenges of targeted radionuclide therapy remains in matching the physical and chemical characteristics of the radionuclide and targeting moiety with the clinical character of the tumor. Molecules and molecular targets that have been used in the past can be classified according to the carrier molecule used to deliver the Auger-electron-emitting radionuclide. These include (1) antibodies, (2) peptides, (3) small molecules, (4) oligonucleotides and peptide nucleic acids (PNAs), (5) proteins, and (6) nanoparticles. The efficacy of targeted radionuclide therapy depends greatly on the ability to increase intranuclear incorporation of the radiopharmaceutical without compromising toxicity. Several strategies to achieve this goal have been proposed in literature. The possibility of transferring tumor therapy based on the emission of Auger electrons from experimental models to patients has vast therapeutic potential, and remains a field of intense research.

  1. Drill-auger

    Energy Technology Data Exchange (ETDEWEB)

    Levkovich, P.E.; Bratisheva, L.L.; Savich, N.S.

    1981-01-01

    The author proposes a drill-auger with a drilling platform, a sectional auger-bit with a drilling-bit crown, a rotational mechanism, and a feed mechanism with vertical chain grippers. Borehole drilling operations are made more effective by drilling from a single drill platform attitude for the entirety of the auger-bit length (which is equal to the screw length). The chain teeth protrude from the auger to a diameter equal to the height of the teeth. The rotary mechanism is platform mounted with two symmetrically deployed rollers having teeth capable of kinematically interfacing with the auger teeth. The feed mechanism consists of a hydraulic jack deployed between the vertical chain protrusion and the auxiliary grippers which are themselves attached in a hinge-like fashion to the hydraulic-jack cylinder and are capable of interfacing with sections of the auger stem.

  2. Improvement of depth selective electron Moessbauer spectroscopy for investigations of locally heterogenous nanosystems

    International Nuclear Information System (INIS)

    Full text: Active use of Moessbauer spectroscopy in various investigations including study of properties of locally heterogeneous systems stipulates continuous improvements of instrumental and methodical base. There has been developed a nondestructive method of depth selective conversion electron Moessbauer spectroscopy (DS CEMS) for obtaining of Moessbauer information from subsurface locally heterogeneous systems with depth resolution about several nm. Precise investigations by this method at a combined installation electron spectrometer - nuclear gamma resonance spectrometer are of special interest. Quality of such investigations first of all depends upon the possibilities of the electron spectrometer. There were found stipulated by the electron spectrometer conditions of achievement of the depth resolution close to physical nanolimit. There was achieved evident success in development of DS CEMS method at high-effective magnetic sector electron spectrometer with double focusing equipped with large area non-equipotential electron source (a sample under investigation) of and with the position-sensitive detector of electrons, which is similar to the detector. The present spectrometer satisfies the conditions found above. It allows also to work with low-energy electrons up to 500 eV including Auger electrons and electrons of true secondary emission. Thickness about several nm with the depth resolution about tenths of nm is studied in the last case at rather high efficiency of measurements. The main aspects of use of internal conversion electrons, Auger electrons and secondary electrons accompanying decay of Moessbauer levels of different nuclei in the method of depth selective electron Moessbauer spectroscopy (DS EMS) were considered. There were recommended optimal variants for use of either that type of electron irradiation and their combinations for a number of solved problems. The electron spectrometer with a sample at a boundary of the magnetic gap corresponds to

  3. Feasibility of In-Trap Conversion Electron Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Weissman, L.; Ames, F.; Aysto, J.; Forstner, O. [CERN, EP-Division (Switzerland); Rinta-Antila, S. [University of Jyvaeskyla, Department of Physics (Finland); Schmidt, P. [J. Gutenberg-Universitaet Mainz, Institut fuer Physik (Germany)

    2001-01-15

    We have used REXTRAP at ISOLDE to test the feasibility of in-trap electron spectroscopy. The results of calculations, experiments with various electron sources as well as a first test with trapped radioactive ions are presented.

  4. Electron-nuclear double resonance spectroscopy (and electron spin-echo envelope modulation spectroscopy) in bioinorganic chemistry

    OpenAIRE

    Hoffman, Brian M.

    2003-01-01

    This perspective discusses the ways that advanced paramagnetic resonance techniques, namely electron-nuclear double resonance (ENDOR) and electron spin-echo envelope modulation (ESEEM) spectroscopies, can help us understand how metal ions function in biological systems.

  5. Electronic properties of atomic layer deposition films, anatase and rutile TiO2 studied by resonant photoemission spectroscopy

    Science.gov (United States)

    Das, C.; Richter, M.; Tallarida, M.; Schmeisser, D.

    2016-07-01

    The TiO2 films are prepared by atomic layer deposition (ALD) method using titanium isopropoxide precursors at 250 °C and analyzed using resonant photoemission spectroscopy (resPES). We report on the Ti2p and O1s core levels, on the valence band (VB) spectra and x-ray absorption spectroscopy (XAS) data, and on the resonant photoelectron spectroscopy (resPES) profiles at the O1s and the Ti3p absorption edges. We determine the elemental abundance, the position of the VB maxima, the partial density of states (PDOS) in the VB and in the conduction band (CB) and collect these data in a band scheme. In addition, we analyze the band-gap states as well as the intrinsic states due to polarons and charge-transfer excitations. These states are found to cause multiple Auger decay processes upon resonant excitation. We identify several of these processes and determine their relative contribution to the Auger signal quantitatively. As our resPES data allow a quantitative analysis of these defect states, we determine the relative abundance of the PDOS in the VB and in CB and also the charge neutrality level. The anatase and rutile polymorphs of TiO2 are analyzed in the same way as the TiO2 ALD layer. The electronic properties of the TiO2 ALD layer are compared with the anatase and rutile polymorphs of TiO2. In our comparative study, we find that ALD has its own characteristic electronic structure that is distinct from that of anatase and rutile. However, many details of the electronic structure are comparable and we benefit from our spectroscopic data and our careful analysis to find these differences. These can be attributed to a stronger hybridization of the O2p and Ti3d4s states for the ALD films when compared to the anatase and rutile polymorphs.

  6. Front-End Board with Cyclone V as a Test High-Resolution Platform for the Auger-Beyond-2015 Front End Electronics

    CERN Document Server

    Szadkowski, Zbigniew

    2014-01-01

    The surface detector (SD) array of the Pierre Auger Observatory containing at present 1680 water Cherenkov detectors spread over an area of 3000 km^2 started to operate since 2004. The currently used Front-End Boards are equipped with no-more produced ACEX and obsolete Cyclone FPGA (40 MSps/15-bit of dynamic range). Huge progress in electronics and new challenges from physics impose a significant upgrade of the SD electronics either to improve a quality of measurements (much higher sampling and much wider dynamic range) or pick-up from a background extremely rare events (new FPGA algorithms based on sophisticated approaches like e.g. spectral triggers or neural networks). Much higher SD sensitivity is necessary to confirm or reject hypotheses critical for a modern astrophysics. The paper presents the Front-End Board (FEB) with the biggest Cyclone V E FPGA 5CEFA9F31I7N, supporting 8 channels sampled with max. 250 MSps @ 14-bit resolution. Considered sampling for the SD is 120 MSps, however, the FEB has been de...

  7. Electron spectroscopy on cuprates and ruthenates

    International Nuclear Information System (INIS)

    The electronic structure of the halo-oxocuprates and ruthenates, which are isostructural to the high temperature superconductor La2-xBaxCuO4, has been investigated with X-ray absorption and photoemission spectroscopy. The halo-oxocuprates exhibit a very stable stoichiometric phase. Sr2CuO2Cl2 has a valence band maximum in the middle of the Brillouin-zone approximately 0.5 eV below the Fermi level. The dispersion of this band along the anti Γ- anti X line agree quite well with calculations for the t-J model. The dispersion along a line 3 parallel to the anti Γ- anti M line is similar to the dispersion predicted for the t-J model. However, the energy position of this peak relative to the valence band maximum does not agrees with the model calculation. Improved agreement can be gained by introducing a diagnonal hopping term in the t-J model. X-ray absorption measurements on Sr2RuO4 indicate that the unoccupied states close to the Fermi level are mainly determined by Ru-4dxz,yz.xy orbitals hybridized with O-2pπ orbitals. A peak observed at 528.5 eV photon energy is probably related to the apical oxygen sites. A relatively high amount of holes close to the Fermi level have O 2pz character. The amount of holes close to the Fermi level with O 2pz character is approximately two times higher than the amount of holes with O 2px,y character

  8. 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...

  9. Titanium oxidation-reduction at low oxygen pressure under electron bombardment

    Energy Technology Data Exchange (ETDEWEB)

    Brasca, R. [Facultad de Ingenieria Quimica, Universidad Nacional del Litoral, Santiago del Estero 2829 (S3000AOM) Santa Fe (Argentina)]. E-mail: rbrasca@fiqus.unl.edu.ar; Passeggi, M.C.G. [Laboratorio de Superficies e Interfaces, INTEC - CONICET and Universidad Nacional del Litoral, Gueemes 3450 (S3000GLN) Santa Fe (Argentina); Ferron, J. [Facultad de Ingenieria Quimica, Universidad Nacional del Litoral, Santiago del Estero 2829 (S3000AOM) Santa Fe (Argentina); Laboratorio de Superficies e Interfaces, INTEC - CONICET and Universidad Nacional del Litoral, Gueemes 3450 (S3000GLN) Santa Fe (Argentina)

    2006-12-05

    The effect of the electron bombardment on the first stages of the titanium oxidation process has been studied by means of Auger Electron Spectroscopy. Using Factor Analysis and the valence electron dependence behaviour of the titanium LMV Auger transition, we found that the process is strongly dependent on the oxygen pressure and electron current density. Depending on the irradiation conditions, films of different thickness and Ti oxidized states are obtained.

  10. Electron-probe microanalysis: x-ray spectroscopy

    International Nuclear Information System (INIS)

    The main principles on X-ray, energy and wave length dispersive spectroscopy are reviewed. In order to allow the choice of the best operating conditions, the importance of the regulation and control systems is underlined. Emission theory, X-rays nature and its interaction with matter and electrons in the matter is shown. The structure, operating procedures and necessary electronics (single channel - analysis chain) automatic-control system for the threshold-energies discrimination and the energy distribution visualization) associated to the wavelength dispersive spectroscopy are described. The focusing control, resolution, influence of chemical bonds and multilayer-structure monochromators relaled to wavelength dispersive spectroscopy are studied. Concerning the energy-dispersive spectroscopy, the detector, preamplifier, amplifier, analog-digital converter, as well as the utilization and control of the spectrometer are described. Problems and instrumental progress on energy-dispersive spectroscopy related to the electronic-noise control, charge collection and light-elements detection are discussed

  11. Some applications of ballistic electron emission microscopy/spectroscopy

    International Nuclear Information System (INIS)

    A brief review of ballistic electron emission microscopy and spectroscopy applications is presented. Results of our ballistic electron emission spectroscopy measurements on cleaved n-GaAs are given. The threshold in ballistic current-voltage characteristic is observed at bias 1.93 V which is high above the expected threshold. Explanation of this effect is given in the frame of present theoretical results. (author)

  12. 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......, and procedures for the correction of measurement errors. The applications of impedance spectroscopy are illustrated with examples from electroceramics and polymer-based dielectric systems. The way in which the technique is applied to the two classes of materials is compared with reference to the different models...

  13. 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.

  14. Diamond Analyzed by Secondary Electron Emission Spectroscopy

    Science.gov (United States)

    Krainsky, Isay L.

    1998-01-01

    Diamond is a promising semiconductor material for novel electronic applications because of its chemical stability and inertness, heat conduction properties, and so-called negative electron affinity (NEA). When a surface has NEA, electrons generated inside the bulk of the material are able to come out into the vacuum without any potential barrier (work function). Such a material would have an extremely high secondary electron emission coefficient o, very high photoelectron (quantum) yield, and would probably be an efficient field emitter. Chemical-vapor-deposited (CVD) polycrystalline diamond films have even more advantages than diamond single crystals. Their fabrication is relatively easy and inexpensive, and they can be grown with high levels of doping--consequently, they can have relatively high conductivity. Because of these properties, diamond can be used for cold cathodes and photocathodes in high-power electronics and in high-frequency and high-temperature semiconductor devices.

  15. Electronic spectroscopy of transition metal dimer

    OpenAIRE

    Qian, Yue; 钱玥

    2013-01-01

    This thesis reports laser spectroscopic studies of gas-phase transition metal dimers using laser ablation/reaction with free jet expansion and laser-induced fluorescence (LIF) spectroscopy technique. Themolecules studied in this work are palladium dimer (Pd2) and vanadium dimer (V2). Many compounds formed from these transition metals are important and functional catalysts in chemical reactions. Therefore, it is of great significance to start from the fundamental level to understand the prope...

  16. Ballistic electron spectroscopy of semiconductor heterostructures

    International Nuclear Information System (INIS)

    A systematic study of electron transport through semiconductor superlattices in the transition region between coherent and scattering induced transport is performed. The measurements are carried out using a hot electron transistor as an electron spectrometer. A quasi monoenergetic, variable energy, ballistic hot electron beam is generated by a tunneling barrier injector and used to probe the intrinsic heterostructure transport properties as a function of a uniform electric field. Under flat band conditions the eigenstates of a periodic structure extend over the entire length of the superlattice forming minibands. From the measured transfer ratios, miniband positions and miniband widths are determined and compared to the results from self consistent calculations. The transmittance of the superlattice at different superlattice bias conditions is measured by varying the energy of the injected hot electron beam. For a superlattice longer than the coherence length, the transmission becomes asymmetric and dependent on the electric field direction. The onset of scattering induced miniband transport is clearly evident and the transition between coherent and incoherent electron transport in superlattices is observed for the first time. A coherence length of 150 nm and a scattering time of 1 ps is determined. The experimental result is in good agreement to a fully three dimensional calculation including interface roughness with typical island sizes of 10 mn. This clearly demonstrates that interface roughness scattering limits the coherence length of ballistic electrons in the superlattice. (author)

  17. Single electron detection and spectroscopy via relativistic cyclotron radiation

    CERN Document Server

    Asner, D M; de Viveiros, L; Doe, P J; Fernandes, J L; Fertl, M; Finn, E C; Formaggio, J A; Furse, D; Jones, A M; Kofron, J N; LaRoque, B H; Leber, M; McBride, E L; Miller, M L; Mohanmurthy, P; Monreal, B; Oblath, N S; Robertson, R G H; Rosenberg, L J; Rybka, G; Rysewyk, D; Sternberg, M G; Tedeschi, J R; Thummler, T; VanDevender, B A; Woods, N L

    2014-01-01

    It has been understood since 1897 that accelerating charges must 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 spec- trometer. We observe the cyclotron radiation emitted by individual magnetically-trapped electrons that are produced with mildly-relativistic energies by a gaseous radioactive source. The relativistic shift in the cyclotron frequency permits a precise electron energy measurement. Precise beta elec- tron 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 demonstrates a fundamentally new approach to precision beta sp...

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

    International Nuclear Information System (INIS)

    A triphenylbromoethylene, 1,1-bis(p-hydroxyphenyl)-2-bromo-2-phenylethylene, Br-BHPE, and a bromosteroidal estrogen, 17α- bromovinylestradiol, BrVE2, were labeled with the Auger electron emitting nuclide bromine-80m, prepared by the [p,n] reaction with 80Se. 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 BrVE2 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 BrVE2 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

  19. 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.

  20. Ultrafast Charge Transfer Visualized by Two-Dimensional Electronic Spectroscopy

    OpenAIRE

    Mančal T.; Milota F.; Hauer J; Christensson N.; Bixner O.; Lukeš V.; Kauffmann H. F.

    2013-01-01

    Two-dimensional electronic spectroscopy (2D-ES) is used to investigate ultrafast excited-state dynamics in a lutetium bisphthalocyanine dimer. Following optical excitation, a chain of electron and hole transfer steps gives rise to characteristic cross-peak dynamics in the electronic 2D spectra. The combination of density matrix propagation and quantum chemical calculations results in a molecular view of the charge transfer dynamics and highlights the role of the counter-ion in providing an en...

  1. Spectral lineshapes in nonlinear electronic spectroscopy.

    Science.gov (United States)

    Nenov, Artur; Giussani, Angelo; Fingerhut, Benjamin P; Rivalta, Ivan; Dumont, Elise; Mukamel, Shaul; Garavelli, Marco

    2015-12-14

    We outline a computational approach for nonlinear electronic spectra, which accounts for the electronic energy fluctuations due to nuclear degrees of freedom and explicitly incorporates the fluctuations of higher excited states, induced by the dynamics in the photoactive state(s). This approach is based on mixed quantum-classical dynamics simulations. Tedious averaging over multiple trajectories is avoided by employing the linearly displaced Brownian harmonic oscillator to model the correlation functions. The present strategy couples accurate computations of the high-lying excited state manifold with dynamics simulations. The application is made to the two-dimensional electronic spectra of pyrene, a polycyclic aromatic hydrocarbon characterized by an ultrafast (few tens of femtoseconds) decay from the bright S2 state to the dark S1 state. The spectra for waiting times t2 = 0 and t2 = 1 ps demonstrate the ability of this approach to model electronic state fluctuations and realistic lineshapes. Comparison with experimental spectra [Krebs et al., New Journal of Physics, 2013, 15, 085016] shows excellent agreement and allows us to unambiguously assign the excited state absorption features.

  2. Electron beam induced oxidation of Ni3Al surfaces : electron flux effects

    NARCIS (Netherlands)

    Koch, S.A.; Palasantzas, G.; Agterveld, D.T.L. van; Hosson, J.Th.M. De

    2002-01-01

    Electron beam irradiation of polycrystalline boron doped Ni3Al (at 300 K and under ultrahigh vacuum conditions) induces fast oxidation. The rate and depth of oxidation initially increase with increasing electron flux as indicated by results from Auger electron spectroscopy. Curves of oxygen developm

  3. 核衰变产生的X射线和俄歇电子数据计算%Data Calculation of X-Ray and Auger Electron Arising from Nuclear Decay

    Institute of Scientific and Technical Information of China (English)

    周春梅; 黄小龙; 吴振东

    2003-01-01

    核衰变过程中,内转换电子发射和电子俘获能在原子电子壳层内留下空穴. 其他原子电子壳层的电子将填补这些空穴,其原子电子位置将重排,并发射X射线和俄歇电子. X射线和俄歇电子的能量由原子电子结合能计算得到,X射线和俄歇电子的强度分别由内转换电子发射和电子俘获在原子电子壳层内留下的空穴数,X射线荧光产额,和空穴转移系数计算得到. 本文简要介绍核衰变产生的X射线和俄歇电子数据的计算方法、计算程序与工作流程,并以核衰变为例说明其具体应用和简要讨论与总结.%In nuclear decay process, internal conversion electron emission and electron capture leave vacancies in atomic shells. The vacancies in atomic shells give rise to rearrangements in the shells which are accompanied by the emission of X-ray and the ejection of Auger electrons. The energies of X-ray and Auger electron can be calculated on the basis of atomic-electron binding energies in different atomic shells. The intensities of X-ray and Auger electron can be also calculated from vacancy number, X-ray fluorescence yield and vacancy transfer coefficient of different atomic shells. The calculation methods of energies and absolute intensities of X-ray and Auger electron arising from nuclear decay are introduced briefly. The calculation codes and flow chart are presented. The application is also given by using some nuclear decays as an example.

  4. 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).

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

    International Nuclear Information System (INIS)

    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

  6. Electron-phonon scattering in molecular electronics: from inelastic electron tunnelling spectroscopy to heating effects

    Energy Technology Data Exchange (ETDEWEB)

    Gagliardi, Alessio; Frauenheim, Thomas; Niehaus, Thomas A [Bremen Center for Computational Materials Science, University of Bremen, D-28359 Bremen (Germany); Romano, Giuseppe; Pecchia, Alessandro; Di Carlo, Aldo [CNR-INFM Department of Electronics Engineering, University of Rome ' Tor Vergata' , Via del Politecnico 1, 00133 Rome (Italy)], E-mail: gagliard@bccms.uni-bremen.de, E-mail: Gagliardi@Ing.uniroma2.it

    2008-06-15

    In this paper, we investigate dissipation in molecular electronic devices. Dissipation is a crucial quantity which determines the stability and heating of the junction. Moreover, several experimental techniques which use inelastically scattered electrons as probes to investigate the geometry in the junction are becoming fundamental in the field. In order to describe such physical effects, a non-equilibrium Green's function (NEGF) method was implemented to include scattering events between electrons and molecular vibrations in current simulations. It is well known that the final heating of the molecule depends also on the ability of the molecule to relax vibrational quanta into the contact reservoirs. A semi-classical rate equation has been implemented and integrated within the NEGF formalism to include this relaxation. The model is based on two quantities: (i) the rate of emission of phonons in the junction by electron-phonon scattering and (ii) a microscopic approach for the computation of the phonon decay rate, accounting for the dynamical coupling between the vibrational modes localized on the molecule and the contact phonons. The method is applied to investigate inelastic electron tunnelling spectroscopy (IETS) signals in CO molecules on Cu(110) substrates as well as dissipation in C{sub 60} molecules on Cu(110) and Si(100) surfaces. It is found that the mechanisms of energy relaxation are highly mode-specific and depend crucially on the lead electronic structure and junction geometry.

  7. Electron-phonon scattering in molecular electronics: from inelastic electron tunnelling spectroscopy to heating effects

    International Nuclear Information System (INIS)

    In this paper, we investigate dissipation in molecular electronic devices. Dissipation is a crucial quantity which determines the stability and heating of the junction. Moreover, several experimental techniques which use inelastically scattered electrons as probes to investigate the geometry in the junction are becoming fundamental in the field. In order to describe such physical effects, a non-equilibrium Green's function (NEGF) method was implemented to include scattering events between electrons and molecular vibrations in current simulations. It is well known that the final heating of the molecule depends also on the ability of the molecule to relax vibrational quanta into the contact reservoirs. A semi-classical rate equation has been implemented and integrated within the NEGF formalism to include this relaxation. The model is based on two quantities: (i) the rate of emission of phonons in the junction by electron-phonon scattering and (ii) a microscopic approach for the computation of the phonon decay rate, accounting for the dynamical coupling between the vibrational modes localized on the molecule and the contact phonons. The method is applied to investigate inelastic electron tunnelling spectroscopy (IETS) signals in CO molecules on Cu(110) substrates as well as dissipation in C60 molecules on Cu(110) and Si(100) surfaces. It is found that the mechanisms of energy relaxation are highly mode-specific and depend crucially on the lead electronic structure and junction geometry

  8. 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.

  9. Electron Spectroscopy: Ultraviolet and X-Ray Excitation.

    Science.gov (United States)

    Baker, A. D.; And Others

    1980-01-01

    Reviews recent growth in electron spectroscopy (54 papers cited). Emphasizes advances in instrumentation and interpretation (52); photoionization, cross-sections and angular distributions (22); studies of atoms and small molecules (35); transition, lanthanide and actinide metal complexes (50); organometallic (12) and inorganic compounds (2);…

  10. 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…

  11. 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...

  12. 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.

  13. Ultrafast Charge Transfer Visualized by Two-Dimensional Electronic Spectroscopy

    Directory of Open Access Journals (Sweden)

    Mančal T.

    2013-03-01

    Full Text Available Two-dimensional electronic spectroscopy (2D-ES is used to investigate ultrafast excited-state dynamics in a lutetium bisphthalocyanine dimer. Following optical excitation, a chain of electron and hole transfer steps gives rise to characteristic cross-peak dynamics in the electronic 2D spectra. The combination of density matrix propagation and quantum chemical calculations results in a molecular view of the charge transfer dynamics and highlights the role of the counter-ion in providing an energetic perturbation which promotes charge transfer across the complex.

  14. Electron coincidence spectroscopy - an introduction to momentum space chemistry

    International Nuclear Information System (INIS)

    The application of electron coincidence spectroscopy or (e,2e) to obtaining detailed information on the dynamic structure of atoms and molecules is discussed. The technique obtains separation energy spectra and spherically averaged electron momentum distributions for each molecular orbital in the valence region. A brief discussion of molecular orbital density functions in momentum space is given. The results using Hartree-Fock wave functions for atomic orbitals and LCAO-MO-SCF wave functions for molecular orbitals are compared with (e,2e) data. The sensitivity of the data to electron correlations in either the initial or final ion many body states is discussed and examples given

  15. Study of Pd--Ta on Si(100) using Auger electron spectroscopy, Rutherford backscattering spectrometry, and variable energy positron annihilation

    Energy Technology Data Exchange (ETDEWEB)

    van der Kolk, G.J.; Kuiper, A.E.T.; Duchateau, J.P.W.B.; Willemsen, M.; Nielsen, B.; Lynn, K.G.

    1989-05-01

    The applicability of Pd/sub x/Ta/sub 1-//sub x/ as a diffusion barrier on Si has been investigated. For this purpose Pd/sub x/Ta/sub 1-//sub x/ films of 200-nm thickness (x ranges from 0 to 1) were deposited on Si(100), and the reaction between overlayer and substrate was studied as a function of temperature. Interaction was found to occur at temperatures increasing with the Ta content. The as-deposited Pd/sub x/Ta/sub 1-//sub x/ films with 0.2less than or equal toxless than or equal to0.6 were found to be amorphous. The amorphous phase had a higher reaction temperature than the crystalline one, causing a discontinuous step in the reaction temperature. Rutherford backscattering spectrometry spectra revealed that for the Pd-rich compositions, first a stoichiometric Pd/sub 2/Si layer formed underneath a pure Ta layer. At higher temperatures TaSi/sub 2/ formed at the surface. For Ta-rich compositions Pd/sub 2/Si formed first as well; however, the reaction temperature was so high that Pd/sub 2/Si grains formed in a Si matrix. The defect density of the Ta layer, which remained after outdiffusion of Pd, was investigated using variable energy positron annihilation. The defect concentration is very high, as deduced from the trapped positron fraction. A model is presented that describes the composition dependence of the reaction temperature.

  16. Using augers to extract minerals

    Energy Technology Data Exchange (ETDEWEB)

    Levkovich, P.Ye.; Meznikov, V.I.; Savich, N.S.

    1981-08-25

    The purpose of the device is to increase productivity based on eliminating empty auger trips. Following drilling the length of the auger away from the (preparatory) working area, the auger section is put in place on the side opposite from the drilled part of the (preparatory) working area. Simultaneous with drilling the other shaft opposite to the preparatory working area, the spindle device for injecting the bit into the drilled out part is set in place. Through it the auger sections are extracted from both shafts (facing each other) directly by moving the spindle device from one shaft to the other.

  17. Binary collision model for neon Auger spectra from neon ion bombardment of the aluminum surface

    Science.gov (United States)

    Pepper, S. V.

    1986-01-01

    A model is developed to account for the angle-resolved Auger spectra from neon ion bombardment of the aluminum surface recently obtained by Pepper and Aron. The neon is assumed to be excited in a single asymmetric neon-aluminum-collision and scattered back into the vacuum where it emits an Auger electron. The velocity of the Auger electron acquires a Doppler shift by virtue of the emission from a moving source. The dependence of the Auger peak shape and energy on the incident ion energy, angle of incidence and on the angle of Auger electron emission with respect to the surface is presented. Satisfactory agreement with the angle resolved experimental observations is obtained. The dependence of the angle-integrated Auger yield on the incident ion energy and angle of incidence is also obtained and shown to be in satisfactory agreement with available experimental evidence.

  18. Communication: Investigation of the electron momentum density distribution of nanodiamonds by electron energy-loss spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Zhenbao; Yang, Bing; Lin, Yangming; Su, Dangsheng, E-mail: dssu@imr.ac.cn [Shenyang National Laboratory of Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Wenhua Road 72, Shenyang 110016 (China)

    2015-12-07

    The electron momentum distribution of detonation nanodiamonds (DND) was investigated by recording electron energy-loss spectra at large momentum transfer in the transmission electron microscope (TEM), which is known as electron Compton scattering from solid (ECOSS). Compton profile of diamond film obtained by ECOSS was found in good agreement with prior photon experimental measurement and theoretical calculation that for bulk diamond. Compared to the diamond film, the valence Compton profile of DND was found to be narrower, which indicates a more delocalization of the ground-state charge density for the latter. Combining with other TEM characterizations such as high-resolution transmission electron spectroscopy, diffraction, and energy dispersive X-ray spectroscopy measurements, ECOSS was shown to be a great potential technique to study ground-state electronic properties of nanomaterials.

  19. Communication: Investigation of the electron momentum density distribution of nanodiamonds by electron energy-loss spectroscopy

    International Nuclear Information System (INIS)

    The electron momentum distribution of detonation nanodiamonds (DND) was investigated by recording electron energy-loss spectra at large momentum transfer in the transmission electron microscope (TEM), which is known as electron Compton scattering from solid (ECOSS). Compton profile of diamond film obtained by ECOSS was found in good agreement with prior photon experimental measurement and theoretical calculation that for bulk diamond. Compared to the diamond film, the valence Compton profile of DND was found to be narrower, which indicates a more delocalization of the ground-state charge density for the latter. Combining with other TEM characterizations such as high-resolution transmission electron spectroscopy, diffraction, and energy dispersive X-ray spectroscopy measurements, ECOSS was shown to be a great potential technique to study ground-state electronic properties of nanomaterials

  20. Inexpensive read-out for coincident electron spectroscopy with a transmission electron microscope at nanometer scale using micro channel plates and multistrip anodes

    International Nuclear Information System (INIS)

    The elemental composition of a sample at nanometer scale is determined by measurement of the characteristic energy of Auger electrons, emitted in coincidence with incoming primary electrons from a microbeam in a scanning transmission electron microscope (STEM). Single electrons are detected with position sensitive detectors, consisting of MicroChannel Plates (MCP) and MultiStrip Anodes (MSA), one for the energy of the Auger electrons (Auger-detector) and one for the energy loss of primary electrons (EELS-detector). The MSAs are sensed with LeCroy 2735DC preamplifiers. The fast readout is based on LeCroy's PCOS III system. On the detection of a coincidence (Event) energy data of Auger and EELS are combined with timing data to an Event word. Event words are stored in list mode in a VME memory module. Blocks of Event words are scanned by transputers in VME and two-dimensional energy histograms are filled using the timing information to obtain a maximal true/accidental ratio. The resulting histograms are stored on disk of a PC-386, which also controls data taking. The system is designed to handle 105 Events per second, 90% of which are accidental. In the histograms the ''true'' to ''accidental'' ratio will be 5. The dead time is 15%. ((orig.))

  1. Study of the electronic properties of cobalt phthalocyanine thin films on poly- and single crystalline gold substrate by photoemission spectroscopies

    Energy Technology Data Exchange (ETDEWEB)

    Petraki, Fotini; Peisert, Heiko; Chasse, Thomas [Institut fuer Physikalische und Theoretische Chemie, Universitaet Tuebingen, Auf der Morgenstelle 8, D-72076 Tuebingen (Germany)

    2010-07-01

    Organic electronics is a new and fast developing sector of microelectronics which aims either to cover applications that are not accessible to conventional silicon semiconductor technology or to decrease the cost of the devices with the use of organic materials. In organic devices, the interfaces between the electrodes and the organic films play an important role, as they determine the injection efficiency by establishing barriers for carrier injection in the organic active layer. Therefore, interface studies contribute to the understanding and improvement of the device performance. In the present study, model experiments concerning the interface formation between Cobalt Phthalocyanine (CoPc) ultra thin films and gold substrate were carried out by X-ray and Ultra-Violet photoelectron spectroscopies (XPS, UPS) as well as Auger spectroscopy (XAES). The experimental data indicate a quite strong interaction between the organic molecules and the metallic substrate, which is confirmed by the presence of additional features at the characteristic Co 2p and CoLVV peaks of the CoPc film at the very first steps of deposition. The valence band structure of CoPc is well resolved while new features are also present for monolayer coverage. Screening mechanisms in XPS and XAES are also discussed.

  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 Plasmonic Nanostructures with Electron Energy - Loss Spectroscopy

    DEFF Research Database (Denmark)

    Raza, Søren

    for nonlocal response. The experimental work comprises the use of electron energy-loss spectroscopy (EELS) to excite and study both localized and propagating surface plasmons in metal structures. Following a short introduction, we present the theoretical foundation to describe nonlocal response in Maxwell...... 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...

  4. Probing Battery Chemistry with Liquid Cell Electron Energy Loss Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Unocic, Raymond R.; Baggetto, Loic; 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. 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. Furthermore, we discuss experimental parameters that influence measurement sensitivity and provide a framework to apply this important analytical method to future in situ electrochemical studies.

  5. In Situ Electron Energy Loss Spectroscopy in Liquids

    CERN Document Server

    Holtz, Megan E; Gao, Jie; Abruña, Héctor D; Muller, David A

    2012-01-01

    In situ scanning transmission electron microscopy (STEM) through liquids is a promising approach for exploring biological and materials processes. However, options for in situ chemical identification are limited: X-ray analysis is precluded because the holder shadows the detector, and electron energy loss spectroscopy (EELS) is degraded by multiple scattering events in thick layers. Here, we explore the limits of EELS for studying chemical reactions in their native environments in real time and on the nanometer scale. The determination of the local electron density, optical gap and thickness of the liquid layer by valence EELS is demonstrated for liquids. By comparing theoretical and experimental plasmon energies, we find that liquids appear to follow the free-electron model that has been previously established for solids. Signals at energies below the optical gap and plasmon energy of the liquid provide a high signal-to-background ratio as demonstrated for LiFePO4 in aqueous solution. The potential for using...

  6. Ultrabroadband two-quantum two-dimensional electronic spectroscopy

    Science.gov (United States)

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

    2016-08-01

    A recent theoretical study proposed that two-quantum (2Q) two-dimensional (2D) electronic spectroscopy should be a background-free probe of post-Hartree-Fock electronic correlations. Testing this theoretical prediction requires an instrument capable of not only detecting multiple transitions among molecular excited states but also distinguishing molecular 2Q signals from nonresonant response. Herein we describe a 2Q 2D spectrometer with a spectral range of 300 nm that is passively phase stable and uses only beamsplitters and mirrors. We developed and implemented a dual-chopping balanced-detection method to resolve the weak molecular 2Q signals. Experiments performed on cresyl violet perchlorate and rhodamine 6G revealed distinct 2Q signals convolved with nonresonant response. Density functional theory computations helped reveal the molecular origin of these signals. The experimental and computational results demonstrate that 2Q electronic spectra can provide a singular probe of highly excited electronic states.

  7. Quantum dynamics and electronic spectroscopy within the framework of wavelets

    International Nuclear Information System (INIS)

    This paper serves as a first-time report on formulating important aspects of electronic spectroscopy and quantum dynamics in condensed harmonic systems using the framework of wavelets, and a stepping stone to our future work on developing anharmonic wavelets. The Morlet wavelet is taken to be the mother wavelet for the initial state of the system of interest. This work reports daughter wavelets that may be used to study spectroscopy and dynamics of harmonic systems. These wavelets are shown to arise naturally upon optical electronic transition of the system of interest. Natural birth of basis (daughter) wavelets emerging on exciting an electronic two-level system coupled, both linearly and quadratically, to harmonic phonons is discussed. It is shown that this takes place through using the unitary dilation and translation operators, which happen to be part of the time evolution operator of the final electronic state. The corresponding optical autocorrelation function and linear absorption spectra are calculated to test the applicability and correctness of the herein results. The link between basis wavelets and the Liouville space generating function is established. An anharmonic mother wavelet is also proposed in the case of anharmonic electron–phonon coupling. A brief description of deriving anharmonic wavelets and the corresponding anharmonic Liouville space generating function is explored. In conclusion, a mother wavelet (be it harmonic or anharmonic) which accounts for Duschinsky mixing is suggested. (paper)

  8. Interfacial Electron Transfer and Transient Photoconductivity Studied with Terahertz Spectroscopy

    Science.gov (United States)

    Milot, Rebecca Lee

    Terahertz spectroscopy is distinguished from other far infrared and millimeter wave spectroscopies by its inherent phase sensitivity and sub-picosecond time resolution making it a versatile technique to study a wide range of physical phenomena. As THz spectroscopy is still a relatively new field, many aspects of THz generation mechanisms have not been fully examined. Using terahertz emission spectroscopy (TES), THz emission from ZnTe(110) was analyzed and found to be limited by two-photon absorption and free-carrier generation at high excitation fluences. Due to concerns about the continued use of fossil fuels, solar energy has been widely investigated as a promising source of renewable energy. Dye-sensitized solar cells (DSSCs) have been developed as a low-cost alternative to conventional photovoltaic solar cells. To solve the issues of the intermittency and inefficient transport associated with solar energy, researchers are attempting to adapt DSSCs for water oxidation and chemical fuel production. Both device designs incorporate sensitizer molecules covalently bound to metal oxide nanoparticles. The sensitizer, which is comprised of a chromophore and anchoring group, absorbs light and transfers an electron from its excited state to the conduction band of the metal oxide, producing an electric current. Using time-resolved THz spectroscopy (TRTS), an optical pump/THz probe technique, the efficiency and dynamics of electron injection from sensitizers to metal oxides was evaluated as a function of the chromophore, its anchoring group, and the metal oxide identity. Experiments for studying fully functioning DSSCs and water oxidation devices are also described. Bio-inspired pentafluorophenyl porphyrin chromophores have been designed and synthesized for use in photoelectrochemical water oxidation cells. Influences on the efficiency and dynamics of electron injection from the chromophores into TiO2 and SnO2 nanoparticles due to changes in both the central substituent to

  9. Modeling ellipsometry and electron energy loss spectroscopy of graphene

    Energy Technology Data Exchange (ETDEWEB)

    Lyon, Keenan A.; Miskovic, Zoran L. [Department of Applied Mathematics, University of Waterloo, 200 University Ave W, N2L 3G1, Waterloo, Ontario (Canada); Diebold, Alain C. [College of Nanoscale Science and Engineering, State University of New York at Albany, 255 Fuller Rd., Albany, New York 12203 (United States); Idrobo, Juan-Carlos [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States)

    2014-03-31

    Recent studies of electronic excitations in graphene by Electron Energy Loss Spectroscopy (EELS) have revealed massive high-frequency peaks assigned to the π and σ+π plasmons [1], which were semi-quantitatively modeled with a two-dimensional, two-fluid hydrodynamic (HD) model [2]. On the other hand, Spectroscopic Ellipsometry (SE) of graphene covers the region of nearly constant absorbance due to graphene’s universal optical conductivity at infrared frequencies, which is not clearly resolved by EELS, and goes up to cover the π-plasmon peak at ultraviolet frequencies [3]. To attempt to model both the SE and EELS, we amend the HD model by including a low-frequency contribution of graphene’s inter-band transitions, while monitoring the fulfillment of the f-sum rule [4] up to frequencies that cover excitations of all valence electrons.

  10. 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+.

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

    OpenAIRE

    Romins Brasca; Luciana Ines Vergara; Mario César Guillermo Passeggi; Julio Ferrón

    2007-01-01

    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+).

  12. Valence Electronic Structure of Aqueous Solutions: Insights from Photoelectron Spectroscopy

    Science.gov (United States)

    Seidel, Robert; Winter, Bernd; Bradforth, Stephen E.

    2016-05-01

    The valence orbital electron binding energies of water and of embedded solutes are crucial quantities for understanding chemical reactions taking place in aqueous solution, including oxidation/reduction, transition-metal coordination, and radiation chemistry. Their experimental determination based on liquid-photoelectron spectroscopy using soft X-rays is described, and we provide an overview of valence photoelectron spectroscopy studies reported to date. We discuss principal experimental aspects and several theoretical approaches to compute the measured binding energies of the least tightly bound molecular orbitals. Solutes studied are presented chronologically, from simple electrolytes, via transition-metal ion solutions and several organic and inorganic molecules, to biologically relevant molecules, including aqueous nucleotides and their components. In addition to the lowest vertical ionization energies, the measured valence photoelectron spectra also provide information on adiabatic ionization energies and reorganization energies for the oxidation (ionization) half-reaction. For solutes with low solubility, resonantly enhanced ionization provides a promising alternative pathway.

  13. Electronic structure of undoped and potassium doped coronene investigated by electron energy-loss spectroscopy

    OpenAIRE

    Roth, Friedrich; Bauer, Johannes; Mahns, Benjamin; Büchner, Bernd; Knupfer, Martin

    2012-01-01

    We performed electron energy-loss spectroscopy studies in transmission in order to obtain insight into the electronic properties of potassium intercalated coronene, a recently discovered superconductor with a rather high transition temperature of about 15\\,K. A comparison of the loss function of undoped and potassium intercalated coronene shows the appearance of several new peaks in the optical gap upon potassium addition. Furthermore, our core level excitation data clearly signal filling of ...

  14. 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. PMID:24927586

  15. Electron spectroscopy of selected atmospheric molecules and hydrocarbons

    Science.gov (United States)

    Davies, Julia Ann

    The thesis presents experimental results obtained by electron impact energy-loss spectroscopy. Differential oscillator strengths (DOS) of selected atmospheric molecules and hydrocarbons and vibrational excitation cross sections of ozone are measured. A critical comparison with earlier experiments and theory (where it exists) is made. The thesis is arranged in seven chapters. The first discusses molecular structure, spectroscopy and electron-molecule scattering as is relevant to the scope of this thesis. The next two chapters describe the experimental apparatus used. A high resolution electron spectrometer produces an electron beam (˜10 nA) incident upon the molecular target. Scattered electrons of selected energy-loss and scattering angle are detected by the spectrometer providing a total apparatus resolution of ˜50 meV. The vacuum system, gas inlet system and power supplies are also discussed. Chapters 4, 5 and 6 contain the main results obtained during postgraduate studies. DOS of selected atmospheric molecules (O2, N2, N2O, CO and CO2) are presented and critically compared with previous optical and synchrotron studies. Good agreement between results validates the experimental apparatus and techniques used in this work. A detailed study of the DOS of small alkanes (CH4, C2H6, C3H8 and C4H10) and small alkenes (C2H4, C3H6 and C4H8) shows similarities and trends in these series. DOS of ozone, O3, are also measured and the vibrational excitation of ozone is investigated as a function of scattering angle (40° ≤ theta ≤ 120°) and inccident energy (3 eV

  16. 8th international conference on electronic spectroscopy and structure

    Energy Technology Data Exchange (ETDEWEB)

    Robinson, Art

    2000-10-16

    Gathering from 33 countries around the world, 408 registrants and a number of local drop-in participants descended on the Clark Kerr Campus of the University of California, Berkeley, from Monday, August 7 through Saturday, August 12, 2000 for the Eighth International Conference on Electronic Structure and Spectroscopy (ICESS8). At the conference, participants benefited from an extensive scientific program comprising more than 100 oral presentations (plenary lectures and invited and contributed talks) and 330 poster presentations, as well as ample time for socializing and a tour of the Advanced Light Source (ALS) at the nearby Lawrence Berkeley National Laboratory.

  17. Tomography of Particle Plasmon Fields from Electron Energy Loss Spectroscopy

    Science.gov (United States)

    Hörl, Anton; Trügler, Andreas; Hohenester, Ulrich

    2013-08-01

    We theoretically investigate electron energy loss spectroscopy (EELS) of metallic nanoparticles in the optical frequency domain. Using a quasistatic approximation scheme together with a plasmon eigenmode expansion, we show that EELS can be rephrased in terms of a tomography problem. For selected single and coupled nanoparticles we extract the three-dimensional plasmon fields from a collection of rotated EELS maps. Our results pave the way for a fully three-dimensional plasmon-field tomography and establish EELS as a quantitative measurement device for plasmonics.

  18. 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

  19. Auger and SIMS spectrometry in microelectronics

    International Nuclear Information System (INIS)

    X-ray microanalysis limitations led to the development of analytical techniques more sensitive to the ''surface'' layer of the samples. The need for these methods arises from the importance of such layers in determining the characteristics of semiconductor devices. Two recent methods of surface analysis are described in this paper, namely the Auger Electron Spectrometry (AES) and the Secondary Ion Mass Spectrometry (SIMS). Various AES and SIMS spectrometers are already available on the market, and are currently used in R and D or production laboratories of the electronic industries

  20. Conversion electron spectroscopy of isobarically purified trapped radioactive ions

    Energy Technology Data Exchange (ETDEWEB)

    Rissanen, J.; Elomaa, V.V.; Eronen, T.; Hakala, J.; Jokinen, A.; Rahaman, S.; Rinta-Antila, S.; Aeystoe, J. [University of Jyvaeskylae, Department of Physics, P.O.B. 35 (Finland)

    2007-11-15

    The feasibility of the JYFLTRAP for in-trap spectroscopy has been studied. Several internally converted transitions have been measured for isomers of fission products with good accuracy. High-resolution spectroscopic data free of source effects have been obtained proving that trapped radioactive ions can provide excellent conversion electron sources. The shortest-lived isomer studied in this work was {sup 117m} Pd with a half-life of 19.1 ms, for which a superior peak-to-total ratio and an excellent line shape at the 9.9 keV conversion electron line have been observed. Detection efficiencies and related phenomena of the present setup are analyzed. (orig.)

  1. Angle resolved electron energy loss spectroscopy on graphite

    Science.gov (United States)

    Diebold, U.; Preisinger, A.; Schattschneider, P.; Varga, P.

    We report on angle resolved electron energy loss spectroscopy (EELS) in reflection mode with low primary energy on a graphite single crystal. Measurements with primary electron energy of 175 eV have been performed in off-Bragg-reflex geometry in two different directions within the (0001) surface plane of the graphite single crystal. In addition, EELS measurements in specular reflection mode with different primary energies and angles of incidence were done in order to distinguish between surface and bulk plasmon losses. The energy losses and the transferred momenta of the losses have been analyzed. The results are compared with the loss functions for bulk and surface excitations calculated from the dielectric function ɛ(ω, q) obtained from TEELS-data (EELS in transmission mode) [Springer Tracts Mod. Phys. 54 (1970) 77].

  2. ESCA [electron spectroscopy for chemical analysis] examination of metal oxides and electronic ceramic materials: The effect of a low-energy argon-ion beam

    International Nuclear Information System (INIS)

    Electronic ceramic materials are increasingly of interest to chemists because there is a growing interest in preparing high purity ceramics by chemical means and because the properties of the ceramics often depend on the chemical state of the elements in the ceramic. The chemical species, e.g. the oxidation state, of a metal in a ceramic can be identified by the analytical technique known as ESCA (electron spectroscopy for chemical analysis). In this work, the application of ESCA to ceramic materials begins with studies of metal oxide powders and examines the effect of a low energy argon ion beam. Two problems that occur with oxide powders and ceramics are surface charging and the formation of carbonates on the surface. Surface charging is generally compensated for by referencing to the carbon contaminant or by flooding the surface with electrons. Referencing to the contaminant peak meets with limited success when compared to the literature. Flooding the surface of oxide powders and ceramics causes peak distortion. Surface carbonates are identified in the carbon region by their separation of -4.5 eV from the contaminant carbon. To examine the effect of a low energy ion beam on metal oxide powders and ceramic powders, both the X-ray photoelectron (XPS) and X-ray induced Auger electron spectra (XAES) of SC2O3, V2O5, Cu2 O, ZnO and SnO2 are examined before and after ion beam exposure. Limited reduction of the metal is noted in the XPS spectra of V2O5. XAES indicates the Sc2O3, Cu2O and SnO2 are also reduced. XAES is especially useful for determining that reduction by the ion beam has occurred. A comparison of ion beam exposed oxide powders and heavily oxidized metal foils (Ti, Zr and Nb) shows that while the powders undergo limited reduction, the oxidized foils are reduced much more significantly with the same sputtering parameters

  3. High resolution carbon and oxygen K-LL Auger spectra of carbon dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Hiltunen, A.; Aksela, S.; Vikor, Gy.; Ricz, S. E-mail: ricz@atomki.hu; Koever, A.; Sulik, B

    1999-06-03

    The proton excited carbon and oxygen K-LL Auger spectra of carbon dioxide were measured using the high-resolution, angular resolving ESA-21 electron spectrometer. The proton impact energy was 1.0 MeV. The transition energies of both K-LL Auger-spectra (oxygen and carbon) are determined and compared with the existing theoretical and earlier experimental data. The experimental line widths full width at half maximum (FWHM) and relative intensities of the Auger lines are determined. The Auger emission was found to be isotropic within the experimental accuracy.

  4. L-shell Auger and Coster-Kronig spectra from relativistic theory

    Science.gov (United States)

    Chen, M. H.; Crasemann, B.; Aoyagi, M.; Mark, H.

    1979-01-01

    The intensities of L-shell Auger and Coster-Kronig transitions in heavy atoms have been calculated relativistically. A detailed comparison is made with measured Auger spectra of Pt and U. The pertinent transition energies were computed from relativistic wave functions with inclusion of the Breit interaction, self-energy, a vacuum-polarization correction, and complete atomic relaxation. Multiplet splitting is found to distribute Auger electrons from certain transitions among several lines. The analysis leads to reassignment of a number of lines in the measured spectra. Lines originally identified as L2-L3Ni in the U spectrum are shown to arise from M4,5 Auger transitions instead.

  5. Development of an (e,2e) electron momentum spectroscopy apparatus using an ultrashort pulsed electron gun

    International Nuclear Information System (INIS)

    An (e,2e) apparatus for electron momentum spectroscopy (EMS) has been developed, which employs an ultrashort-pulsed incident electron beam with a repetition rate of 5 kHz and a pulse duration in the order of a picosecond. Its instrumental design and technical details are reported, involving demonstration of a new method for finding time-zero. Furthermore, EMS data for the neutral Ne atom in the ground state measured by using the pulsed electron beam are presented to illustrate the potential abilities of the apparatus for ultrafast molecular dynamics, such as by combining EMS with the pump-and-probe technique.

  6. Determining the static electronic and vibrational energy correlations via two-dimensional electronic-vibrational spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Hui; Lewis, Nicholas H. C.; 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, Californial 94720 (United States); Kavli Energy NanoSciences Institute at Berkeley, Berkeley, California 94720 (United States)

    2015-05-07

    Changes in the electronic structure of pigments in protein environments and of polar molecules in solution inevitably induce a re-adaption of molecular nuclear structure. Both changes of electronic and vibrational energies can be probed with visible or infrared lasers, such as two-dimensional electronic spectroscopy or vibrational spectroscopy. The extent to which the two changes are correlated remains elusive. The recent demonstration of two-dimensional electronic-vibrational (2DEV) spectroscopy potentially enables a direct measurement of this correlation experimentally. However, it has hitherto been unclear how to characterize the correlation from the spectra. In this paper, we present a theoretical formalism to demonstrate the slope of the nodal line between the excited state absorption and ground state bleach peaks in the spectra as a characterization of the correlation between electronic and vibrational transition energies. We also show the dynamics of the nodal line slope is correlated to the vibrational spectral dynamics. Additionally, we demonstrate the fundamental 2DEV spectral line-shape of a monomer with newly developed response functions.

  7. 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.

    2016-01-01

    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. PMID:26924846

  8. Nanogap structures: combining enhanced Raman spectroscopy and electronic transport.

    Science.gov (United States)

    Natelson, Douglas; Li, Yajing; Herzog, Joseph B

    2013-04-21

    Surface-enhanced Raman spectroscopy (SERS) is an experimental tool for accessing vibrational and chemical information, down to the single molecule level. SERS typically relies on plasmon excitations in metal nanostructures to concentrate the incident radiation and to provide an enhanced photon density of states to couple emitted radiation to the far field. Many common SERS platforms involve metal nanoparticles to generate the required electromagnetic enhancements. Here we concentrate on an alternative approach, in which the relevant plasmon excitations are supported at a truly nanoscale gap between extended electrodes, rather than discrete subwavelength nanoparticles. The ability to fabricate precise gaps on demand, and in some cases to tune the gap size in situ, combined with the additional capability of simultaneous electronic transport measurements of the nanogap, provides access to information not previously available in standard SERS. We summarize the rich plasmonic physics at work in these extended systems and highlight the recent state of the art including tip-enhanced Raman spectroscopy (TERS) and the application of mechanical break junctions and electromigrated junctions. We describe in detail how we have performed in situ gap-enhanced Raman measurements of molecular-scale junctions while simultaneously subjecting these structures to electronic transport. These extended electrode structures allow us to study the pumping of vibrational modes by the flow of tunneling electrons, as well as the shifting of vibrational energies due to the applied bias. These experiments extend SERS into a tool for examining fundamental processes of dissipation, and provide insight into the mechanisms behind SERS spectral diffusion. We conclude with a brief discussion of future directions. PMID:23385304

  9. Stochastic stimulated electronic x-ray Raman spectroscopy

    CERN Document Server

    Kimberg, Victor

    2015-01-01

    Resonant inelastic x-ray scattering (RIXS) is a well-established tool for studying electronic, nuclear and collective dynamics of excited atoms, molecules and solids. An extension of this powerful method to a time-resolved probe technique at x-ray free electron lasers (XFELs) to ultimately unravel ultrafast chemical and structural changes on a femtosecond time scale is often challenging, due to the small signal rate in conventional implementations at XFELs that rely on the usage of a monochromator set up to select a small frequency band of the broadband, spectrally incoherent XFEL radiation. Here, we suggest an alternative approach, based on stochastic spectroscopy, that uses the full bandwidth of the incoming XFEL pulses. Our proposed method is relying on stimulated resonant inelastic x-ray scattering, where in addition to a pump pulse that resonantly excites the system a probe pulse on a specific electronic inelastic transition is provided, that serves as seed in the stimulated scattering process. The limit...

  10. Radioprotection by DMSO against the biological effects of incorporated radionuclides in vivo. Comparison with other radioprotectors and evidence for indirect action of Auger electrons

    International Nuclear Information System (INIS)

    Dimethyl sulfoxide (DMSO) was studied for its capacity to protect against the biological effects of chronic irradiation by incorporated radionuclides. Spermatogenesis in mice was used as experimental model and spermatogonial cell survival was the biological endpoint. DMSO was injected intratesticularly 4 h prior to a similar injection of the radiochemical and the spermhead survival determined. Iodine-125 was localized in either the cytoplasm (H125IPDM) or in the DNA (125IUdR) of the tecticular cells. Protection was observed against the high-LET type effects of DNA-bound 125I as well as the low-LET effects of cytoplasmically localized 125I with dose modification factors (DMF) of 3.1±1.0 and 4.4±1.0 respectively. No protection (DMF=1.1±0.1) was observed against the effects of high-LET 5.3 MeV alpha partciles of 210Po. The present findings provide supporting evidence that the mechanism responsible for the extreme biological damage caused by DNA-bound Auger emitters is largely radical mediated and therefore indirect in nature. (orig.)

  11. Electronic spectroscopy of organic semiconductors in helium nanodroplets

    Energy Technology Data Exchange (ETDEWEB)

    Dvorak, Matthieu; Buenermann, Oliver; Stienkemeier, Frank [Physikalisches Institut, Universitaet Freiburg (Germany); Eisfeld, Alexander [MPI-PKS, Dresden (Germany)

    2009-07-01

    Spectroscopy of molecules or molecular complexes embedded in helium nanodroplets is an outstanding tool to characterize electronic and geometric structures. Due to the unique properties of the superfluid droplets, helium nanodroplets isolation (HENDI) spectroscopy reaches far better spectral resolution than usually obtained in organic solvents or on thin films. We applied HENDI to investigate the absorption and emission spectra of the PTCDA molecule and its complexes. The PTCDA monomer shows sharp vibronic lines (<1 cm-1) that can be assigned to different internal vibration modes as well as overtones and combination modes. PTCDA complexes show different spectral features. Sharp lines, red shifted compared to the monomer absorptions are assigned to T-structured dimers. Additionally, very broad absorption lines are observed. These are assigned to complexes forming sandwich structures. Recent theoretical calculations can reproduce the spectra and support this interpretation. Furthermore, in comparison to absorption spectra, emission intensities allow to study the amount of internal relaxation before emitting a photon, giving further insight into the involved processes.

  12. Identification of irradiated chicken meat using electron spin resonance spectroscopy

    International Nuclear Information System (INIS)

    Studies were carried out on detection of irradiation treatment in chicken using electron spin resonance (ESR) spectroscopy. The effect of gamma- irradiation treatment on radiation induced signal in different types of chicken namely, broiler, deshi and layers was studied. Irradiation treatment induced a characteristic ESR signal that was not detected in non-irradiated samples. The shape of the signal was not affected by type of the bone. The intensity of radiation induced ESR signal was affected by factors such as absorbed radiation dose, bone type irradiation temperature, post-irradiation storage, post-irradiation cooking and age of the bird. Deep-frying resulted in the formation of a symmetric signal that had a different shape and was weaker than the radiation induced signal. This technique can be effectively used to detect irradiation treatment in bone-in chicken meat even if stored and/or subjected to various traditional cooking procedures. (author)

  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. Bore-auger servo-mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Levkovich, P.Ye.; Bolotov, N.L.; Kiselev, Ye.I.; Opal' ko, L.L.; Podubniy, V.I.; Savich, N.S.; Tverezyy, Yu.F.

    1980-06-06

    A bore-auger servo-mechanism is proposed for a drilling machine. This unit consists of a drilling bit, an auger boring section with a screw-type surface, upper and lower cutting disks, mounted onto the supports between the main auger sections, and a linear auger section with lateral ties. In order to simplify construction, the upper cutting disk is equipped with its own auger bits, both below and above the disks, thus facilitating interaction with the screw-type surface of the auger sections.

  15. Electron-transfer acceleration investigated by time resolved infrared spectroscopy.

    Science.gov (United States)

    Vlček, Antonín; Kvapilová, Hana; Towrie, Michael; Záliš, Stanislav

    2015-03-17

    Ultrafast electron transfer (ET) processes are important primary steps in natural and artificial photosynthesis, as well as in molecular electronic/photonic devices. In biological systems, ET often occurs surprisingly fast over long distances of several tens of angströms. Laser-pulse irradiation is conveniently used to generate strongly oxidizing (or reducing) excited states whose reactions are then studied by time-resolved spectroscopic techniques. While photoluminescence decay and UV-vis absorption supply precise kinetics data, time-resolved infrared absorption (TRIR) and Raman-based spectroscopies have the advantage of providing additional structural information and monitoring vibrational energy flows and dissipation, as well as medium relaxation, that accompany ultrafast ET. We will discuss three cases of photoinduced ET involving the Re(I)(CO)3(N,N) moiety (N,N = polypyridine) that occur much faster than would be expected from ET theories. [Re(4-N-methylpyridinium-pyridine)(CO)3(N,N)](2+) represents a case of excited-state picosecond ET between two different ligands that remains ultrafast even in slow-relaxing solvents, beating the adiabatic limit. This is caused by vibrational/solvational excitation of the precursor state and participation of high-frequency quantum modes in barrier crossing. The case of Re-tryptophan assemblies demonstrates that excited-state Trp → *Re(II) ET is accelerated from nanoseconds to picoseconds when the Re(I)(CO)3(N,N) chromophore is appended to a protein, close to a tryptophan residue. TRIR in combination with DFT calculations and structural studies reveals an interaction between the N,N ligand and the tryptophan indole. It results in partial electronic delocalization in the precursor excited state and likely contributes to the ultrafast ET rate. Long-lived vibrational/solvational excitation of the protein Re(I)(CO)3(N,N)···Trp moiety, documented by dynamic IR band shifts, could be another accelerating factor. The last

  16. Attosecond photoelectron spectroscopy of electron transport in solids

    International Nuclear Information System (INIS)

    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

  17. 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

  18. 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.

  19. Tetrachloridocuprates(II—Synthesis and Electron Paramagnetic Resonance (EPR Spectroscopy

    Directory of Open Access Journals (Sweden)

    Peter Strauch

    2012-02-01

    Full Text Available Ionic liquids (ILs on the basis of metal containing anions and/or cations are of interest for a variety of technical applications e.g., synthesis of particles, magnetic or thermochromic materials. We present the synthesis and the results of electron paramagnetic resonance (EPR spectroscopic analyses of a series of some new potential ionic liquids based on tetrachloridocuprates(II, [CuCl4]2−, with different sterically demanding cations: hexadecyltrimethylammonium 1, tetradecyltrimethylammonium 2, tetrabutylammonium 3 and benzyltriethylammonium 4. The cations in the new compounds were used to achieve a reasonable separation of the paramagnetic Cu(II ions for EPR spectroscopy. The EPR hyperfine structure was not resolved. This is due to the exchange broadening, resulting from still incomplete separation of the paramagnetic Cu(II centers. Nevertheless, the principal values of the electron Zeemann tensor (g║ and g┴ of the complexes could be determined. Even though the solid substances show slightly different colors, the UV/Vis spectra are nearly identical, indicating structural changes of the tetrachloridocuprate moieties between solid state and solution. The complexes have a promising potential e.g., as high temperature ionic liquids, as precursors for the formation of copper chloride particles or as catalytic paramagnetic ionic liquids.

  20. Electronic structure and electron energy-loss spectroscopy of ZrO2 zirconia

    Science.gov (United States)

    Dash, L. K.; Vast, Nathalie; Baranek, Philippe; Cheynet, Marie-Claude; Reining, Lucia

    2004-12-01

    The atomic and electronic structures of zirconia are calculated within density functional theory, and their evolution is analyzed as the crystal-field symmetry changes from tetrahedral [cubic (c-ZrO2) and tetragonal (t-ZrO2) phases] to octahedral (hypothetical rutile ZrO2 ), to a mixing of these symmetries (monoclinic phase, m-ZrO2 ). We find that the theoretical bulk modulus in c-ZrO2 is 30% larger than the experimental value, showing that the introduction of yttria in zirconia has a significant effect. Electronic structure fingerprints which characterize each phase from their electronic spectra are identified. We have carried out electron energy-loss spectroscopy experiments at low momentum transfer and compared these results to the theoretical spectra calculated within the random phase approximation. We show a dependence of the valence and 4p ( N2,3 edge) plasmons on the crystal structure, the dependence of the latter being brought into the spectra by local-field effects. Last, we attribute low energy excitations observed in EELS of m-ZrO2 to defect states 2eV above the top of the intrinsic valence band, and the EELS fundamental band gap value is reconciled with the 5.2 or 5.8eV gaps determined by vacuum ultraviolet spectroscopy.

  1. 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.

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

    International Nuclear Information System (INIS)

    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 ∼0.15 eV energy resolution with an electron probe size of ∼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 Y1Ba2Cu3O7-δ high-temperature superconductor illustrates these concepts and shows what kind of information can be accessed by VEELS

  3. The Pierre Auger Observatory Upgrade - Preliminary Design Report

    CERN Document Server

    Aab, A; Aglietta, M; Ahn, E J; Samarai, I Al; Albuquerque, I F M; Allekotte, I; Allison, P; Almela, A; Castillo, J Alvarez; Alvarez-Muñiz, J; Batista, R Alves; Ambrosio, M; Aminaei, A; Anchordoqui, L; Andringa, S; Aramo, C; Arqueros, F; Arsene, N; Asorey, H; Assis, P; Aublin, J; Ave, M; Avenier, M; Avila, G; Awal, N; Badescu, A M; Barber, K B; Bäuml, J; 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; Brack, J; Brancus, I; Bridgeman, A; Brogueira, P; Brown, W C; 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; Neto, J R T de Mello; De Mitri, I; de Oliveira, J; de Souza, V; del Peral, L; Deligny, O; Dembinski, H; Dhital, N; Di Giulio, C; Di Matteo, A; Diaz, J C; Castro, M L Díaz; Diogo, F; Dobrigkeit, C; Docters, W; D'Olivo, J C; Dorofeev, A; Hasankiadeh, Q Dorosti; 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; Fernandes, M; Fick, B; Figueira, J M; Filevich, A; Filipčič, A; Fox, B D; Fratu, O; Freire, M M; Fuchs, B; Fujii, T; García, B; 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; Berisso, M Gómez; Vitale, P F Gómez; 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; Hemery, N; Herve, 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; Kégl, B; Keilhauer, B; Keivani, A; Kemp, E; Kieckhafer, R M; Klages, H O; Kleifges, M; Kleinfeller, J; Krause, R; Krohm, N; Krömer, O; Kuempel, D; Mezek, G Kukec; Kunka, N; LaHurd, D; Latronico, L; Lauer, R; Lauscher, M; Lautridou, P; Coz, S Le; Lebrun, D; Lebrun, P; de Oliveira, M A Leigui; Letessier-Selvon, A; Lhenry-Yvon, I; Link, K; Lopes, L; López, R; Casado, A López; Louedec, K; Lu, L; Lucero, A; Malacari, M; Maldera, S; Mallamaci, M; Maller, J; Mandat, D; Mantsch, P; Mariazzi, A G; Marin, V; Mariş, I C; Marsella, G; Martello, D; Martin, L; Martinez, H; Bravo, O Martínez; Martraire, D; Meza, J J Masías; 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; Meyhandan, R; 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; Muller, M A; Müller, G; Müller, S; Mussa, R; Navarra, G; 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; Ochilo, L; Oikonomou, F; Olinto, A; Pacheco, N; Selmi-Dei, D Pakk; 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; Purrello, V; Quel, E J; Querchfeld, S; Quinn, S; Rautenberg, J; Ravel, O; Ravignani, D; Reinert, D; Revenu, B; Ridky, J; Riggi, S; Risse, M; Ristori, P; Rizi, V; de Carvalho, W Rodrigues; Fernandez, G Rodriguez; Rojo, J Rodriguez; Rodríguez-Frías, M D; Rogozin, D; Rosado, J; Roth, M; Roulet, E; Rovero, A C; Saffi, S J; Saftoiu, A; Salamida, F; Salazar, H; Saleh, A; Greus, F Salesa; Salina, G; Sánchez, F; Sanchez-Lucas, P; Santos, E; Santos, E M; Sarazin, F; Sarkar, B; Sarmento, R; 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; Sidelnik, I; Sigl, G; Sima, O; Śmiałkowski, A; Šmída, R; Snow, G R; Sommers, P; Sorokin, J; Squartini, R; Srivastava, Y N; Stanca, D; Stanič, S; Stapleton, J; Stasielak, J; Stephan, M; Stutz, A; Suarez, F; Suomijärvi, T; Supanitsky, A D; Sutherland, M S; Swain, J; Szadkowski, Z; Taborda, O A; Tapia, A; Tepe, A; Theodoro, V M; Timmermans, C; Peixoto, C J Todero; Toma, G; Tomankova, L; Tomé, B; Tonachini, A; Elipe, G Torralba; Machado, D Torres; Travnicek, P; Trini, M; Ulrich, R; Unger, M; Urban, M; Galicia, J F Valdés; Valiño, I; Valore, L; van Aar, G; van Bodegom, P; Berg, A M van den; van Velzen, S; van Vliet, A; Varela, E; Cárdenas, B Vargas; 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; Zhu, Y; Zimmermann, B; Ziolkowski, M; Zong, Z; Zuccarello, F

    2016-01-01

    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 m$^2$ 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.

  4. 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.

  5. Direct and Auger Electron-Induced, Single- and Double-Strand Breaks on Plasmid DNA Caused by 99mTc-Labeled Pyrene Derivatives and the Effect of Bonding Distance.

    Science.gov (United States)

    Reissig, Falco; Mamat, Constantin; Steinbach, Joerg; Pietzsch, Hans-Juergen; Freudenberg, Robert; Navarro-Retamal, Carlos; Caballero, Julio; Kotzerke, Joerg; Wunderlich, Gerd

    2016-01-01

    It is evident that 99mTc causes radical-mediated DNA damage due to Auger electrons, which were emitted simultaneously with the known γ-emission of 99mTc. We have synthesized a series of new 99mTc-labeled pyrene derivatives with varied distances between the pyrene moiety and the radionuclide. The pyrene motif is a common DNA intercalator and allowed us to test the influence of the radionuclide distance on damages of the DNA helix. In general, pUC 19 plasmid DNA enables the investigation of the unprotected interactions between the radiotracers and DNA that results in single-strand breaks (SSB) or double-strand breaks (DSB). The resulting DNA fragments were separated by gel electrophoresis and quantified by fluorescent staining. Direct DNA damage and radical-induced indirect DNA damage by radiolysis products of water were evaluated in the presence or absence of the radical scavenger DMSO. We demonstrated that Auger electrons directly induced both SSB and DSB in high efficiency when 99mTc was tightly bound to the plasmid DNA and this damage could not be completely prevented by DMSO, a free radical scavenger. For the first time, we were able to minimize this effect by increasing the carbon chain lengths between the pyrene moiety and the 99mTc nuclide. However, a critical distance between the 99mTc atom and the DNA helix could not be determined due to the significantly lowered DSB generation resulting from the interaction which is dependent on the type of the 99mTc binding motif. The effect of variable DNA damage caused by the different chain length between the pyrene residue and the Tc-core as well as the possible conformations of the applied Tc-complexes was supplemented with molecular dynamics (MD) calculations. The effectiveness of the DNA-binding 99mTc-labeled pyrene derivatives was demonstrated by comparison to non-DNA-binding 99mTcO4-, since nearly all DNA damage caused by 99mTcO4- was prevented by incubating with DMSO. PMID:27583677

  6. Electronic structure of germanium selenide investigated using ultra-violet photo-electron spectroscopy

    International Nuclear Information System (INIS)

    The valence band electronic structure of GeSe single crystals has been investigated using angle resolved photoemission spectroscopy (ARPES) and x-ray photoelectron spectroscopy. The experimentally observed bands from ARPES, match qualitatively with our LDA-based band structure calculations along the Γ–Z, Γ–Y and Γ–T symmetry directions. The valence band maximum occurs nearly midway along the Γ–Z direction, at a binding energy of −0.5 eV, substantiating the indirect band gap of GeSe. Non-dispersive features associated with surface states and indirect transitions have been observed. The difference in hybridization of Se and Ge 4p orbitals leads to the variation of dispersion along the three symmetry directions. The predominance of the Se 4pz orbitals, evidenced from theoretical calculations, may be the cause for highly dispersive bands along the Γ–T direction. Detailed electronic structure analysis reveals the significance of the cation–anion 4p orbitals hybridization in the valence band dispersion of IV–VI semiconductors. This is the first comprehensive report of the electronic structure of a GeSe single crystal using ARPES in conjugation with theoretical band structure analysis. (paper)

  7. Analysis of contaminants on electronic components by reflectance FTIR spectroscopy

    International Nuclear Information System (INIS)

    The analysis of electronic component contaminants by infrared spectroscopy is often a difficult process. Most of the contaminants are very small, which necessitates the use of microsampling techniques. Beam condensers will provide the required sensitivity but most require that the sample be removed from the substrate before analysis. Since it can be difficult and time consuming, it is usually an undesirable approach. Micro ATR work can also be exasperating, due to the difficulty of positioning the sample at the correct place under the ATR plate in order to record a spectrum. This paper describes a modified reflection beam condensor which has been adapted to a Nicolet 7199 FTIR. The sample beam is directed onto the sample surface and reflected from the substrate back to the detector. A micropositioning XYZ stage and a close-focusing telescope are used to position the contaminant directly under the infrared beam. It is possible to analyze contaminants on 1 mm wide leads surrounded by an epoxy matrix using this device. Typical spectra of contaminants found on small circuit boards are included

  8. Precessed electron beam electron energy loss spectroscopy of graphene: Beyond channelling effects

    International Nuclear Information System (INIS)

    The effects of beam precession on the Electron Energy Loss Spectroscopy (EELS) signal of the carbon K edge in a 2 monolayer graphene sheet are studied. In a previous work, we demonstrated the use of precession to compensate for the channeling-induced reduction of EELS signal when in zone axis. In the case of graphene, no enhancement of EELS signal is found in the usual experimental conditions, as graphene is not thick enough to present channeling effects. Interestingly, though it is found that precession makes it possible to increase the collection angle, and, thus, the overall signal, without a loss of signal-to-background ratio

  9. 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)

  10. Ramsey interferometry for resonant Auger decay through core-excited states

    Science.gov (United States)

    Chatterjee, Souvik; Nakajima, Takashi

    2016-08-01

    We theoretically investigate the electron dynamics in Ne atoms involving core-excited states through the Ramsey scheme with a pair of time-delayed x-ray pulses. Irradiation of Ne atoms by the ˜1 femtosecond x-ray pulse simultaneously populates two core-excited states, and an identical but time-delayed x-ray pulse probes the dynamics of the core-excited electron wave packet which is subject to the resonant Auger decay. The energy-integrated total Auger electron yield and energy-resolved Auger electron spectra in the time domain show periodic structures due to the temporal evolution of the wave packet, from which we can obtain the counterpart in the frequency domain through the Fourier transformation. The Auger electron energy spectra in the time as well as frequency domains show the interference patterns between the two Auger electron wave packets released into the continuum from the superposition of two core-excited states at different times. These spectra are important to clarify the individual contribution of the different Auger decay channels upon core excitation by the x-ray pulse.

  11. New insights into micro/nanoscale combined probes (nanoAuger, μXPS) to characterize Ag/Au@SiO2 core-shell assemblies.

    Science.gov (United States)

    Ledeuil, J B; Uhart, A; Soulé, S; Allouche, J; Dupin, J C; Martinez, H

    2014-10-01

    This work has examined the elemental distribution and local morphology at the nanoscale of core@shell Ag/Au@SiO2 particles. The characterization of such complex metal/insulator materials becomes more efficient when using an initial cross-section method of preparation of the core@shell nanoparticles (ion milling cross polisher). The originality of this route of preparation allows one to obtain undamaged, well-defined and planar layers of cross-cut nano-objects. Once combined with high-resolution techniques of characterization (XPS, Auger and SEM), the process appears as a powerful way to minimize charging effects and enhance the outcoming electron signal (potentially affected by the topography of the material) during analysis. SEM experiments have unambiguously revealed the hollow-morphology of the metal core, while Auger spectroscopy observations showed chemical heterogeneity within the particles (as silver and gold are randomly found in the core ring). To our knowledge, this is the first time that Auger nano probe spectroscopy has been used and successfully optimized for the study of some complex metal/inorganic interfaces at such a high degree of resolution (≈12 nm). Complementarily, XPS Au 4f and Ag 3d peaks were finally detected attesting the possibility of access to the whole chemistry of such nanostructured assemblies.

  12. XUV Spectroscopy of Isochorically Heated Metals at the Free Electron Laser Flash

    International Nuclear Information System (INIS)

    Spectroscopic investigations of metals, interacting with intense, femtosecond XUV pulses at 13.5 nm wavelength (92 eV photon energy), are presented. The experiments were performed at the FEL FLASH of the DESY lab in Hamburg. Metallic samples are dominantly ionized by direct photo-absorption of inner-shell bound electrons. Processes such as radiative and Auger decays lead to emission of fluorescence radiation as well as bremsstrahlung and ionic line radiation. By applying QMD and Monte-Carlo simulation, we compare our experimental observations with theoretical predictions and gain insight into the complex interaction of metals with intense XUV radiation. This topic shows novel features of isochoric heating of warm dense plasmas by FEL radiation, complementary to heating by optical laser irradiation. (author)

  13. 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

  14. Electronic and optical properties of Fe, Pd, and Ti studied by reflection electron energy loss spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Tahir, Dahlang [Department of Physics, Hasanuddin University, Makassar 90245 (Indonesia); Kraaer, Jens; Tougaard, Sven [Department of Physics, Chemistry, and Pharmacy, University of Southern Denmark, DK-5230 Odense M (Denmark)

    2014-06-28

    We have studied the electronic and optical properties of Fe, Pd, and Ti by reflection electron energy-loss spectroscopy (REELS). REELS spectra recorded for primary energies in the range from 300 eV to 10 keV were corrected for multiple inelastically scattered electrons to determine the effective inelastic-scattering cross section. The dielectric functions and optical properties were determined by comparing the experimental inelastic-electron scattering cross section with a simulated cross section calculated within the semi-classical dielectric response model in which the only input is Im(−1/ε) by using the QUEELS-ε(k,ω)-REELS software package. The complex dielectric functions ε(k,ω), in the 0–100 eV energy range, for Fe, Pd, and Ti were determined from the derived Im(−1/ε) by Kramers-Kronig transformation and then the refractive index n and extinction coefficient k. The validity of the applied model was previously tested and found to give consistent results when applied to REELS spectra at energies between 300 and 1000 eV taken at widely different experimental geometries. In the present paper, we provide, for the first time, a further test on its validity and find that the model also gives consistent results when applied to REELS spectra in the full range of primary electron energies from 300 eV to 10000 eV. This gives confidence in the validity of the applied method.

  15. Atom location using scanning transmission electron microscopy based on electron energy loss spectroscopy

    International Nuclear Information System (INIS)

    Full text: The technique of atom location by channelling enhanced microanalysis (ALCHEMI) using cross section data, measured as a function of electron beam orientation, has been widely implemented by many researchers. The accurate application of ALCHEMI, usually based on energy dispersive x-ray analysis (EDX), requires knowledge, from first principles, of the relative delocalization of the inner-shell ionization interaction (see for example Oxley and Allen, 1998; Oxley et al., 1999). Scanning transmission electron microscopy (STEM) based on electron energy loss spectroscopy (EELS) also provides information about the location of atoms of different types within the crystal lattice. Unlike high angle annular dark field (HAADF), EELS provides a unique signal for each atom type. In conjunction with highly focused probes, allowing near atomic resolution, this makes possible, in principle, the application of ALCHEMI like techniques to STEM images to determine the distribution of impurities within the unit cell. The accurate interpretation of STEM results requires that both the inner-shell ionization interaction and resulting ionization cross section or image be correctly modelled. We present model calculations demonstrating the in principle application of ALCHEMI type techniques to STEM images pertinent to EELS. The inner-shell ionisation interaction is modelled using Hartree-Fock wave functions to describe the atomic bound states and Hartree-Slater wave functions to describe the continuum states. The wave function within the crystal is calculated using boundary conditions appropriate for a highly focussed probe (Rossouw and Allen, 2001) and STEM images or ionisation cross sections are simulated using an inelastic cross section formulation that correctly accounts for the contribution from both dynamical electrons and those dechannelled by absorptive scattering processes such as thermal diffuse scattering (TDS). Copyright (2002) Australian Society for Electron Microscopy

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

    Science.gov (United States)

    Ferreira da Silva, F.; Lange, E.; Limão-Vieira, P.; Jones, N. C.; Hoffmann, S. V.; Hubin-Franskin, M.-J.; Delwiche, J.; Brunger, M. J.; Neves, R. F. C.; Lopes, M. C. A.; de Oliveira, E. M.; da Costa, R. F.; Varella, M. T. do N.; Bettega, M. H. F.; Blanco, F.; García, G.; Lima, M. A. P.; Jones, D. B.

    2015-10-01

    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.

  17. 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.

  18. Detection of irradiated lamb meat by electron spin resonance spectroscopy

    International Nuclear Information System (INIS)

    Present paper describes the potential of ESR spectroscopy for identification of radical ions in irradiated lamb meat containing bone. Irradiation induced a characteristic ESR signal due to CO2- in the bone tissue which was not detected in the non-irradiated samples. Intensity of ESR signal was proportional to irradiation dose up to 5 kGy. These results have shown that ESR spectroscopy can be effectively used to detect irradiated lamb meat containing bone tissue. (author). 2 refs., 2 figs

  19. Electronic spectroscopy and electronic structure of the smallest metal clusters: the diatomic 3D transition metal aluminides

    Science.gov (United States)

    Behm, Jane M.; Morse, Michael D.

    1994-06-01

    A systematic study of the electronic spectroscopy, electronic structure, and chemical bonding has been initiated for the 3d series of diatomic transition metal aluminides. This report provides a review of the progress to date, with specific emphasis on AlCa, AlV, AlCr, AlMn, AlCo, AlNi, AlCu, and AlZn.

  20. X-ray laser spectroscopy with an electron beam ion trap at the free electron laser LCLS

    International Nuclear Information System (INIS)

    We present a first laser spectroscopy experiment in the keV energy regime, performed at the Free-Electron Laser LCLS at Stanford. An electron beam ion trap was used to provide a target of highly charged O, F and Fe ions. The resonant fluorescence spectra obtained for various transitions were calibrated to simultaneously measured Lyman lines of hydrogenic ions.

  1. Auger recombination of dark excitons in WS2 and WSe2 monolayers

    Science.gov (United States)

    Danovich, Mark; Zólyomi, Viktor; Fal'ko, Vladimir I.; Aleiner, Igor L.

    2016-09-01

    We propose a novel phonon assisted Auger process unique to the electronic band structure of monolayer transition metal dichalcogenides (TMDCs), which dominates the radiative recombination of ground state excitons in tungsten based TMDCs. Using experimental and density functional theory computed values for the exciton energies, spin-orbit splittings, optical matrix element, and the Auger matrix elements, we find that the Auger process begins to dominate at carrier densities as low as {10}9-10 {{cm}}-2, thus providing a plausible explanation for the low quantum efficiencies reported for these materials.

  2. Theory of attosecond absorption spectroscopy in krypton

    DEFF Research Database (Denmark)

    Baggesen, Jan Conrad; Lindroth, Eva; Madsen, Lars Bojer

    2012-01-01

    A theory for time-domain attosecond pump–attosecond probe photoabsorption spectroscopy is formulated and related to the atomic response. The theory is illustrated through a study of attosecond absorption spectroscopy in krypton. The atomic parameters entering the formulation such as energies and...... Auger widths, as well as wave functions and dipole coupling matrix elements, are determined by accurate many-body structure calculations. We create a hole in a valence shell by an attosecond pump, couple an inner-shell electron to the hole by an attosecond probe, and then monitor the formation of the...

  3. 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.

  4. 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.

  5. 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

  6. 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.

  7. The electron spectroscopy for chemical analysis microscopy beamline data acquisition system at ELETTRA

    Science.gov (United States)

    Gariazzo, C.; Krempaska, R.; Morrison, G. R.

    1996-07-01

    The electron spectroscopy for chemical analysis (ESCA) microscopy data acquisition system enables the user to control the imaging and spectroscopy modes of operation of the beamline ESCA microscopy at ELETTRA. It allows the user to integrate all experiment, beamline and machine operations in one single environment. The system also provides simple data analysis for both spectra and images data to guide further data acquisition.

  8. Bandgap determination of P(VDF–TrFE) copolymer film by electron energy loss spectroscopy

    Indian Academy of Sciences (India)

    Dipankar Mandal; K Henkel; K Müller; D Schmeißer

    2010-08-01

    The ferroelectric of poly(vinylidene fluoride trifluoroethylene), P(VDF–TrFE) is confirmed for 100 nm thickness spin coated copolymer film. The homogeneous coverage of the copolymer film is investigated by the help of X-ray photoelectron spectroscopy (XPS). Most importantly, the existing bandgap in the crystalline phase of the copolymer is determined directly from the electron energy loss spectroscopy (EELS).

  9. Atomic scale imaging and spectroscopy of individual electron trap states using force detected dynamic tunnelling

    International Nuclear Information System (INIS)

    We report the first atomic scale imaging and spectroscopic measurements of electron trap states in completely non-conducting surfaces by dynamic tunnelling force microscopy/spectroscopy. Single electrons are dynamically shuttled to/from individual states in thick films of hafnium silicate and silicon dioxide. The new method opens up surfaces that are inaccessible to the scanning tunnelling microscope for imaging and spectroscopy on an atomic scale.

  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. PMID:26397312

  11. Magnetic field influence on Auger effect on shallow donors in CdF2:Mn+ luminescence

    International Nuclear Information System (INIS)

    Direct observation of the suppression of the Auger effect on shallow donors by magnetic field in the luminescence of manganese ions in semiconducting CdF2:Mn crystals is presented. The magnetic field decreases the probability of the Auger effect, which is spin-dependent energy transfer from the manganese ions to the electrons occupying shallow donors. This results in the increase in the decay times of the luminescence. (author)

  12. Soft x-ray spectroscopy for probing electronic and chemical states of battery materials

    Science.gov (United States)

    Wanli, Yang; Ruimin, Qiao

    2016-01-01

    The formidable challenge of developing high-performance battery system stems from the complication of battery operations, both mechanically and electronically. In the electrodes and at the electrode-electrolyte interfaces, chemical reactions take place with evolving electron states. In addition to the extensive studies of material synthesis, electrochemical, structural, and mechanical properties, soft x-ray spectroscopy provides unique opportunities for revealing the critical electron states in batteries. This review discusses some of the recent soft x-ray spectroscopic results on battery binder, transition-metal based positive electrodes, and the solid-electrolyte-interphase. By virtue of soft x-ray’s sensitivity to electron states, the electronic property, the redox during electrochemical operations, and the chemical species of the interphases could be fingerprinted by soft x-ray spectroscopy. Understanding and innovating battery technologies need a multimodal approach, and soft x-ray spectroscopy is one of the incisive tools to probe the chemical and physical evolutions in batteries.

  13. 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.

  14. 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

  15. ELECTRON-INDUCED VIBRATIONAL SPECTROSCOPY - A NEW AND UNIQUE TOOL TO UNRAVEL THE MOLECULAR-STRUCTURE OF POLYMER SURFACES

    NARCIS (Netherlands)

    PIREAUX, JJ; GREGOIRE, C; CAUDANO, R; VILAR, MR; BRINKHUIS, R; SCHOUTEN, AJ

    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

  16. Vacuum ultraviolet spectroscopy of some hydrocarbons by electron impact technique

    International Nuclear Information System (INIS)

    A detailed description of the construction and operation of the electron impact spectrometer of the Electron Impact Laboratory at the Chemistry Institute of Federal University of Rio de Janeiro are presented. The main characteristics of this spectrometer are: incident energy from 0.5 to 3.0 KeV; angular range from -600 to + 600; energy loss from 0 to 500 eV; energy resolution from 0.5 to 2.5 eV and; electron velocity analyser equal to electrostatic (Mollenstedt type. The data acquisition system is based on a microcomputer Motorola; recently an APPLE II system has been incorporated to the spectrometer. Electron energy loss spectra for the nitrogen molecule as well as for some hydrocarbons (C2H6, C2H4, C2H2) have been obtained. The data were converted into double differential cross sections and generalized oscillator strenghts. (author)

  17. 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...

  18. 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-...

  19. Study of KLL Auger processes for light elements above Z = 10. [Review

    Energy Technology Data Exchange (ETDEWEB)

    Carlson, T.A.; Dress, W.B.; Nyberg, G.L.

    1977-01-01

    A comprehensive review is given of the KLL Auger spectrum for members of the third row of the periodic table. This group contains the lightest elements wherein an Auger process can occur without the direct participation of the valence shell. Recent Auger spectra induced by x-ray photoionization on Mg, Al, and Si metals and their oxides are given as well as preliminary results on salts of Na and K, and for comparison, the LMM spectra of RbCl. Results were combined with previous experimental data and theory in order to obtain an overview. Four topics concerned with Auger processes are discussed: Energies, relative intensities, chemical shifts, and satellite structure. Interlaced throughout is a discussion of the role played by the chemical environment and electron correlation.

  20. 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

  1. 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

  2. Study of electron-irradiated silicon thin films using transient photocurrent spectroscopy

    OpenAIRE

    Reynolds, S; Astakhov, O.; Smirnov, V.(Joint Institute for Nuclear Research, Dubna, Russia)

    2014-01-01

    Electron irradiation of silicon thin films creates localised states, which degrade theiropto-electronic properties. We present a series of transient photocurrent spectroscopy (TPC)measurements on electron-irradiated amorphous and microcrystalline silicon films, annealed atprogressively increasing temperatures. This has enabled localised states associated with bothdangling bonds and conduction band tails to be examined over a wide energy range.Trends inthe evolution of the DOS following electr...

  3. Action spectroscopy of gas-phase carboxylate anions by multiple photon IR electron detachment/attachment

    CERN Document Server

    Steill, Jeffrey D

    2008-01-01

    We report on a form of gas-phase anion action spectroscopy based on infrared multiple photon electron detachment and subsequent capture of the free electrons by a neutral electron scavenger in a Fourier Transform Ion Cyclotron Resonance (FTICR) mass spectrometer. This method allows one to obtain background-free spectra of strongly bound anions, for which no dissociation channels are observed. The first gas-phase spectra of the acetate and propionate anions are presented using SF6 as electron scavenger and a free electron laser as source of intense and tunable infrared radiation. To validate the method, we compare infrared spectra obtained through multiple photon electron detachment/attachment and multiple photon dissociation for the benzoate anion. In addition, different electron acceptors are used, comparing both associative and dissociative electron capture. The relative energies of dissociation (by CO2 loss) and electron detachment are investigated for all three anions by DFT and CCSD(T) methods. DFT calcu...

  4. 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.

  5. Two-Dimensional Electronic Spectroscopy of a Model Dimer System

    Directory of Open Access Journals (Sweden)

    Prokhorenko V.I.

    2013-03-01

    Full Text Available Two-dimensional spectra of a dimer were measured to determine the timescale for electronic decoherence at room temperature. Anti-correlated beats in the crosspeaks were observed only during the period corresponding to the measured homogeneous lifetime.

  6. Electronic structure of palladium and its relation to uv spectroscopy

    DEFF Research Database (Denmark)

    Christensen, N.E.

    1976-01-01

    The electronic-energy-band structure of palladium has been calculated by means of the relativistic augmented-plane-wave method covering energies up to 30 eV above the Fermi level. The optical interband transitions producing structure in the dielectric function up to photon energies of 25 eV have...

  7. 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 t

  8. Cavity ring down spectroscopy with a free-electron laser

    NARCIS (Netherlands)

    Engeln, R.; van den Berg, E.; Meijer, G.; Lin, L.; Knippels, G.M.H.; van der Meer, A. F. G.

    1997-01-01

    A cavity ring down (CRD) absorption experiment is performed with a free-electron laser (FEL) operating in the 10-11 mu m region. A short infrared pulse of approximately 20 ns, sliced from the much longer FEL pulse, is used to measure CRD spectra of ethylene in two different ways. First, ''

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

    International Nuclear Information System (INIS)

    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.

  10. Spectroscopy of Argon Excited in an Electron Beam Ion Trap

    Energy Technology Data Exchange (ETDEWEB)

    Trabert, E

    2005-04-18

    Argon is one of the gases best investigated and most widely used in plasma discharge devices for a multitude of applications that range from wavelength reference standards to controlled fusion experiments. Reviewing atomic physics and spectroscopic problems in various ionization stages of Ar, the past use and future options of employing an electron beam ion trap (EBIT) for better and more complete Ar data in the x-ray, EUV and visible spectral ranges are discussed.

  11. Single-atom electron energy loss spectroscopy of light elements

    OpenAIRE

    Senga, Ryosuke; Suenaga, Kazu

    2015-01-01

    Light elements such as alkali metal (lithium, sodium) or halogen (fluorine, chlorine) are present in various substances and indeed play significant roles in our life. Although atomic behaviours of these elements are often a key to resolve chemical or biological activities, they are hardly visible in transmission electron microscope because of their smaller scattering power and higher knock-on probability. Here we propose a concept for detecting light atoms encaged in a nanospace by means of e...

  12. Imaging electron dynamics with time- and angle-resolved photoelectron spectroscopy

    Science.gov (United States)

    Popova-Gorelova, Daria; Küpper, Jochen; Santra, Robin

    2016-07-01

    We theoretically study how time- and angle-resolved photoemission spectroscopy can be applied for imaging coherent electron dynamics in molecules. We consider a process in which a pump pulse triggers coherent electronic dynamics in a molecule by creating a valence electron hole. An ultrashort extreme ultraviolet probe pulse creates a second electron hole in the molecule. Information about the electron dynamics is accessed by analyzing angular distributions of photoemission probabilities at a fixed photoelectron energy. We demonstrate that a rigorous theoretical analysis, which takes into account the indistinguishability of transitions induced by the ultrashort, broadband probe pulse and electron hole correlation effects, is necessary for the interpretation of time- and angle-resolved photoelectron spectra. We show how a Fourier analysis of time- and angle-resolved photoelectron spectra from a molecule can be applied to follow its electron dynamics by considering photoelectron distributions from an indole molecular cation with coherent electron dynamics.

  13. 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.

  14. 30 CFR 77.1503 - Augering equipment; overhead protection.

    Science.gov (United States)

    2010-07-01

    ... UNDERGROUND COAL MINES Auger Mining § 77.1503 Augering equipment; overhead protection. (a) Auger machines which are exposed to highwall hazards, together with all those parts of any coal elevating conveyors... connecting or disconnecting auger sections under a highwall, at least one person shall be assigned to...

  15. Strong electronic correlation effects in coherent multidimensional nonlinear optical spectroscopy.

    Science.gov (United States)

    Karadimitriou, M E; Kavousanaki, E G; Dani, K M; Fromer, N A; Perakis, I E

    2011-05-12

    We discuss a many-body theory of the coherent ultrafast nonlinear optical response of systems with a strongly correlated electronic ground state that responds unadiabatically to photoexcitation. We introduce a truncation of quantum kinetic density matrix equations of motion that does not rely on an expansion in terms of the interactions and thus applies to strongly correlated systems. For this we expand in terms of the optical field, separate out contributions to the time-evolved many-body state due to correlated and uncorrelated multiple optical transitions, and use "Hubbard operator" density matrices to describe the exact dynamics of the individual contributions within a subspace of strongly coupled states, including "pure dephasing". Our purpose is to develop a quantum mechanical tool capable of exploring how, by coherently photoexciting selected modes, one can trigger nonlinear dynamics of strongly coupled degrees of freedom. Such dynamics could lead to photoinduced phase transitions. We apply our theory to the nonlinear response of a two-dimensional electron gas (2DEG) in a magnetic field. We coherently photoexcite the two lowest Landau level (LL) excitations using three time-delayed optical pulses. We identify some striking temporal and spectral features due to dynamical coupling of the two LLs facilitated by inter-Landau-level magnetoplasmon and magnetoroton excitations and compare to three-pulse four-wave-mixing (FWM) experiments. We show that these features depend sensitively on the dynamics of four-particle correlations between an electron-hole pair and a magnetoplasmon/magnetoroton, reminiscent of exciton-exciton correlations in undoped semiconductors. Our results shed light into unexplored coherent dynamics and relaxation of the quantum Hall system (QHS) and can provide new insight into non-equilibrium co-operative phenomena in strongly correlated systems.

  16. 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) = 872.4 an...

  17. Multidimensional electronic spectroscopy of phycobiliproteins from cryptophyte algae

    Science.gov (United States)

    Turner, Daniel

    2011-03-01

    We describe new spectroscopic measurements which reveal additional information regarding the observed quantum coherences in proteins extracted from photosynthetic algae. The proteins we investigate are the phycobiliproteins phycoerythrin 545 and phycocyanin 645. Two new avenues have been explored. We describe how changes to the chemical and biological environment impact the quantum coherence present in the 2D electronic correlation spectrum. We also use new multidimensional spectroscopic techniques to reveal insights into the nature of the quantum coherence and the nature of the participating states.

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

    Energy Technology Data Exchange (ETDEWEB)

    Hamad, K.S.

    2000-05-01

    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.

  19. Applications of time-domain spectroscopy to electron-phonon coupling dynamics at surfaces.

    Science.gov (United States)

    Matsumoto, Yoshiyasu

    2014-10-01

    Photochemistry is one of the most important branches in chemistry to promote and control chemical reactions. In particular, there has been growing interest in photoinduced processes at solid surfaces and interfaces with liquids such as water for developing efficient solar energy conversion. For example, photoinduced charge transfer between adsorbates and semiconductor substrates at the surfaces of metal oxides induced by photogenerated holes and electrons is a core process in photovoltaics and photocatalysis. In these photoinduced processes, electron-phonon coupling plays a central role. This paper describes how time-domain spectroscopy is applied to elucidate electron-phonon coupling dynamics at metal and semiconductor surfaces. Because nuclear dynamics induced by electronic excitation through electron-phonon coupling take place in the femtosecond time domain, the pump-and-probe method with ultrashort pulses used in time-domain spectroscopy is a natural choice for elucidating the electron-phonon coupling at metal and semiconductor surfaces. Starting with a phenomenological theory of coherent phonons generated by impulsive electronic excitation, this paper describes a couple of illustrative examples of the applications of linear and nonlinear time-domain spectroscopy to a simple adsorption system, alkali metal on Cu(111), and more complex photocatalyst systems. PMID:25139240

  20. Spectroscopy of Two Dimensional Electron Systems Comprising Exotic Quasiparticles

    Science.gov (United States)

    Rhone, Trevor David Nathaniel

    In this dissertation I present inelastic and elastic light scattering studies of collective states emerging from interactions in electron systems confined to two dimensions. These studies span the first, second and third Landau levels. I report for the first time, high energy excitations of composite fermions in the quantum fluid at nu = 1/3. The high energies discovered represent excitations across multiple composite fermion energy levels, demonstrating the topological robustness of the fractional quantum Hall state at nu = 1/3. This study sets the ground work for similar measurements of states in the second Landau level, such as those at nu = 5/2. I present the first light scattering studies of low energy excitations of quantum fluids in the second Landau level. The study of low energy excitations of the quantum fluid at 3 ≥ nu ≥ 5/2 reveals a rapid loss of spin polarization for nu ≲ 3, as monitored by the intensity of the spin wave excitation at the Zeeman energy. The emergence of a continuum of low-lying excitations for nu ≲ 3 reveals competing quantum phases in the second Landau level with intriguing roles of spin degrees of freedom and phase inhomogeneity. The first light scattering studies of the electron systems in the third Landau level are reported here. Measurements of low energy excitations and their spin degrees of freedom reveal contrasting behavior of states in the second and third Landau levels. I discuss these measurements in the context of the charge density wave phases, that are believed, by some, to dominate the third Landau level, and suggest ways of verifying this belief using light scattering. Distinct behavior in the dispersion of the spin wave at nu = 3 is measured for the first time. The study may highlight differences in the first and second Landau levels that are manifested through the electron wavefunctions. In addition to intra-Landau level measurements, inter- Landau level studies are also reported. The results of which reveal

  1. 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.

  2. 48-Channel electron detector for photoemission spectroscopy and microscopy

    Science.gov (United States)

    Gregoratti, L.; Barinov, A.; Benfatto, E.; Cautero, G.; Fava, C.; Lacovig, P.; Lonza, D.; Kiskinova, M.; Tommasini, R.; Mähl, S.; Heichler, W.

    2004-01-01

    We show that it is possible to use a multichannel electron detector in a zone plate based photoemission spectromicroscopy in a snap shot mode to reduce the total acquisition time for a given counting time by 50% relative to the standard scanning mode while preserving the feature of the spectra. We describe the result of tests performed at Elettra using its microbeam (150 nm) together with a 48-channel detector designed for the PHOIBOS 100 analyzer optimized for extremely small x-ray sources. We also give a short summary of the technical features of the detector and describe one possible calibration procedure for its use in the snap shot mode. We show initial results from using this device to perform chemical maps of surfaces at a resolution of 150 nm.

  3. Imaging electron dynamics with time- and angle-resolved photoelectron spectroscopy

    CERN Document Server

    Popova-Gorelova, Daria; Santra, Robin

    2016-01-01

    We theoretically study how time- and angle-resolved photoemission spectroscopy can be applied for imaging coherent electron dynamics in molecules. We consider a process in which a pump pulse triggers coherent electronic dynamics in a molecule by creating a valence electron hole. An ultrashort extreme ultraviolet (XUV) probe pulse creates a second electron hole in the molecule. Information about the electron dynamics is accessed by analyzing angular distributions of photoemission probabilities at a fixed photoelectron energy. We demonstrate that a rigorous theoretical analysis, which takes into account the indistinguishability of transitions induced by the ultrashort, broadband probe pulse and electron hole correlation effects, is necessary for the interpretation of time- and angle-resolved photoelectron spectra. We show how a Fourier analysis of time- and angle-resolved photoelectron spectra from a molecule can be applied to follow its electron dynamics by considering photoelectron distributions from an indol...

  4. Note: Electron energy spectroscopy mapping of surface with scanning tunneling microscope

    Science.gov (United States)

    Li, Meng; Xu, Chunkai; Zhang, Panke; Li, Zhean; Chen, Xiangjun

    2016-08-01

    We report a novel scanning probe electron energy spectrometer (SPEES) which combines a double toroidal analyzer with a scanning tunneling microscope to achieve both topography imaging and electron energy spectroscopy mapping of surface in situ. The spatial resolution of spectroscopy mapping is determined to be better than 0.7 ± 0.2 μm at a tip sample distance of 7 μm. Meanwhile, the size of the field emission electron beam spot on the surface is also measured, and is about 3.6 ± 0.8 μm in diameter. This unambiguously demonstrates that the spatial resolution of SPEES technique can be much better than the size of the incident electron beam.

  5. Frenkel exciton model of electron energy loss spectroscopy in α-PTCDA

    International Nuclear Information System (INIS)

    Recent experimental findings concerning electron energy loss spectroscopy in α-Perylene-tetracarboxylic-dianhydride are analysed in terms of a Frenkel exciton model. Taking into account the energy dispersion of excitations with finite momentum transfer, the k-dependence of the dielectric tensor and the corresponding electron energy loss functions can be calculated. The exciton dispersion with a minimum at k0 yields a red shift of the lineshape of loss functions at large k, as observed experimentally

  6. Electron-spectroscopy study of YbXCu4 (X=Ag,Au,Pd)

    International Nuclear Information System (INIS)

    We have studied the electronic structure of the heavy-electron compounds YbXCu4, with X = Ag,Au,Pd, using x-ray photoemission and bremsstrahlung isochromat spectroscopies. Consistent with other evidence of small Kondo temperatures, we find that Yb in this system is nearly trivalent and that Kondo features in the Yb 4f BIS spectra are either absent or weak

  7. Visualizing plasmon coupling in closely-spaced chains of Ag nanoparticles by electron energy loss spectroscopy

    OpenAIRE

    Song, Fengqi; Wang, Tingyu; Wang, Xuefeng; Xu, Changhui; He, Longbing; Wan, Jianguo; Van Haesendonck, Chris; Simon P. Ringer; Han, Min; Liu, Zongwen; Wang, Guanghou

    2012-01-01

    Anisotropic plasmon coupling in closely-spaced chains of Ag nanoparticles was visualized using the electron energy loss spectroscopy in a scanning transmission electron microscope. For dimers as the simplest chain, mapping the plasmon excitations with nanometers' spatial resolution and 0.27 eV energy resolution intuitively identified two coupling plasmons. The in-phase mode redshifted from the ultraviolet region as the inter-particle spacing was reduced, reaching the visible range at 2.7 eV. ...

  8. Using Electron Paramagnetic Resonance Spectroscopy To Facilitate Problem Solving in Pharmaceutical Research and Development.

    Science.gov (United States)

    Mangion, Ian; Liu, Yizhou; Reibarkh, Mikhail; Williamson, R Thomas; Welch, Christopher J

    2016-08-19

    As new chemical methodologies driven by single-electron chemistry emerge, process and analytical chemists must develop approaches to rapidly solve problems in this nontraditional arena. Electron paramagnetic resonance spectroscopy has been long known as a preferred technique for the study of paramagnetic species. However, it is only recently finding application in contemporary pharmaceutical development, both to study reactions and to track the presence of undesired impurities. Several case studies are presented here to illustrate its utility in modern pharmaceutical development efforts.

  9. Electron spectroscopy in the fundamental process of electron-nucleus bremsstrahlung

    International Nuclear Information System (INIS)

    Within the scope of this thesis the fundamental process of electron-nucleus bremsstrahlung was studied in inverse kinematics at the Experimental Storage Ring ESR at GSI. For the system U88+ + N2 at 90 MeV/u it was shown, that by using inverse kinematics coincidence measurements between the scattered electron and the emitted photon can be performed for the case, in which the incoming electron transfers almost all of its kinetic energy onto the emitted photon. The sensitivity to the fundamental process could be achieved by measuring triple differential cross sections as a function of the emission angle of the photon and the scattered electron as well as the energy of the scattered electron. The optics of the magnetic electron spectrometer used were thoroughly revised and optimized to the experimental requirements. Analyzing different coincidences in this collision system, it was possible to determine the contributions to the electron distribution arising from radiative electron capture to the projectile continuum, nonradiative electron capture to the projectile continuum, and electron loss to the projectile continuum. The experimental results of each of these processes were compared to theoretical calculations. The electron spectra for the radiative and the nonradiative electron capture to continuum clearly reproduce the opposite asymmetry predicted by theory. Furthermore electron spectra for collisions of U28+ with different gases were measured.

  10. Multiplet-Splitting of the Quasi-Atomic-Like Core-Valence-Valence Auger Spectra of Zinc Metal

    Institute of Scientific and Technical Information of China (English)

    YUAN Jian-Min

    2001-01-01

    Multiplet-splitting of the quasi-atomic-like core-valence-valence (CVV) Auger spectra of zinc metal is calculated by explicitly considering the so-called hole-hole interaction in the final valence states of the Auger transition. We assume that before the Auger transition occurs, the occupied valence states relax to screen the core-hole which results in a redistribution of the valence electrons, in particular within the atom that contains a hole in the core. The supercell method is used to calculate the electronic states concerned by the Auger transition, which is accomplished by the self-consistent full-potential linearized augmented plane wave method. In each supercell, one atom is considered to have a core-hole and many others without it. Due to relaxation and screening, the valence states at the site of the Auger transition are more localized compared with those in the ground-state metal. The multiplet peaks of the quasi-atomic-like CVV Auger spectra of zinc metal are obtained by calculating the Auger transition matrix elements between the referred states.

  11. The role of X-ray spectroscopy in understanding the geometric and electronic structure of nitrogenase.

    Science.gov (United States)

    Kowalska, Joanna; DeBeer, Serena

    2015-06-01

    X-ray absorption (XAS) and X-ray emission spectroscopy (XES) provide element specific probes of the geometric and electronic structures of metalloprotein active sites. As such, these methods have played an integral role in nitrogenase research beginning with the first EXAFS studies on nitrogenase in the late 1970s. Herein, we briefly explain the information that can be extracted from XAS and XES. We then highlight the recent applications of these methods in nitrogenase research. The influence of X-ray spectroscopy on our current understanding of the atomic structure and electronic structure of iron molybdenum cofactor (FeMoco) is emphasized. Contributions of X-ray spectroscopy to understanding substrate interactions and cluster biosynthesis are also discussed. This article is part of a Special Issue entitled: Fe/S proteins: Analysis, structure, function, biogenesis and diseases.

  12. Identification of irradiated cashew nut by electron paramagnetic resonance spectroscopy.

    Science.gov (United States)

    Sanyal, Bhaskar; Sajilata, M G; Chatterjee, Suchandra; Singhal, Rekha S; Variyar, Prasad S; Kamat, M Y; Sharma, Arun

    2008-10-01

    Cashew nut samples were irradiated at gamma-radiation doses of 0.25, 0.5, 0.75, and 1 kGy, the permissible dose range for insect disinfestation of food commodities. A weak and short-lived triplet (g = 2.004 and hfcc = 30 G) along with an anisotropic signal (g perpendicular = 2.0069 and g parallel = 2.000) were produced immediately after irradiation. These signals were assigned to that of cellulose and CO 2 (-) radicals. However, the irradiated samples showed a dose-dependent increase of the central line (g = 2.0045 +/- 0.0002). The nature of the free radicals formed during conventional processing such as thermal treatment was investigated and showed an increase in intensity of the central line (g = 2.0045) similar to that of irradiation. Characteristics of the free radicals were studied by their relaxation and thermal behaviors. The present work explores the possibility to identify irradiated cashew nuts from nonirradiated ones by the thermal behaviors of the radicals beyond the period, when the characteristic electron paramagnetic resonance spectral lines of the cellulose free radicals have essentially disappeared. In addition, this study for the first time reports that relaxation behavior of the radicals could be a useful tool to distinguish between roasted and irradiated cashew nuts.

  13. 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 as ...

  14. Continuum probe two-dimensional electronic spectroscopy of the photosystem II reaction center

    Directory of Open Access Journals (Sweden)

    Ogilvie J. P.

    2013-03-01

    Full Text Available We report two-dimensional electronic spectroscopy of the photosystem II reaction center, collected in the pump-probe geometry employing a continuum probe. This enables observation of ion bands that report on intermediates in the charge separation process.

  15. Application of (e,2e) Spectroscopy to the Electronic Structure of Valence Electrons in Crystalline and Amorphous Solids

    OpenAIRE

    Dennison, JR; Ritter, A. L.

    1996-01-01

    This review presents theoretical and experimental aspects of (e,2e) spectroscopy specific to the study of crystalline and amorphous solids. The cross section for (e,2e) scattering is proportional to the spectral momentum density of the ejected electron under certain approximations. The theoretical framework for interpreting (e,2e) measurements is summarized here and general properties of the spectral momentum density of solids are discussed. Different designs of the (e,2e) spectrometer are de...

  16. 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.

  17. 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.

  18. Development of the web-based NIST X-ray Photoelectron Spectroscopy (XPS) Database

    OpenAIRE

    Angela Y. Lee; Blakeslee, Dorothy M; Powell, Cedric J; Rumble, Jr., John

    2006-01-01

    The first Web-based version of the NIST X-ray Photoelectron Spectroscopy Database (XPSDB) is described. The current database, built from a relational database management system (RDBMS), contains critically evaluated data with over 19,000 line positions, chemical shifts, doublet splittings, and energy separations of photoelectron and Auger-electron lines. It is available free of charge to the public through the Internet at http://srdata.nist.gov/xps/.

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

    International Nuclear Information System (INIS)

    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

  20. 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

  1. Development of Holmium-163 Electron-Capture Spectroscopy with Transition-Edge Sensors

    Science.gov (United States)

    Croce, M. P.; Rabin, M. W.; Mocko, V.; Kunde, G. J.; Birnbaum, E. R.; Bond, E. M.; Engle, J. W.; Hoover, A. S.; Nortier, F. M.; Pollington, A. D.; Taylor, W. A.; Weisse-Bernstein, N. R.; Wolfsberg, L. E.; Hays-Wehle, J. P.; Schmidt, D. R.; Swetz, D. S.; Ullom, J. N.; Barnhart, T. E.; Nickles, R. J.

    2016-08-01

    Calorimetric decay energy spectroscopy of electron-capture-decaying isotopes is a promising method to achieve the sensitivity required for electron neutrino mass measurement. The very low total nuclear decay energy (Q_EC based isotope production, isolation, and purification of ^{163}Ho. We have developed transition-edge sensors for this measurement and methods for incorporating ^{163}Ho into high-resolution microcalorimeters, and have measured the electron-capture spectrum of ^{163}Ho. We present our work in these areas and discuss the measured spectrum and its comparison to current theory.

  2. 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...... developed a method based on electron energy loss spectroscopy (EELS) data acquisition and analyses, which enables determination of the boron speciation in a series of ternary alkali borosilicate glasses with constant molar ratios. A script for the fast acquisition of EELS has been designed, from which...

  3. Electron energy-loss spectroscopy of quasi-one-dimensional cuprates and vanadates

    International Nuclear Information System (INIS)

    In a combination of experimental and theoretical methods in this thesis the electronic structures of quasi-one-dimensional cuprates and vanadates were studied. For this the momentum-dependent loss function was measured by means of the electron energy-loss spectroscopy in transmission on monocrystals of Li2CuO2, CuGeO3, V2O5 and α'-NaVO5. The comparison of the experimental data with results from band-structure and cluster calculations allowed conclusions on the mobility and correlations of the electrons in these systems

  4. High-harmonic transient grating spectroscopy of NO2 electronic relaxation

    CERN Document Server

    Ruf, H; Ferré, A; Thiré, N; Bertrand, J B; Bonnet, L; Cireasa, R; Constant, E; Corkum, P B; Descamps, D; Fabre, B; Larregaray, P; Mével, E; Petit, S; Pons, B; Staedter, D; Wörner, H J; Villeneuve, D M; Mairesse, Y; Halvick, P; Blanchet, V

    2012-01-01

    We study theoretically and experimentally the electronic relaxation of NO2 molecules excited by absorption of one ~400 nm pump photon. Semi-classical simulations based on trajectory surface hopping calculations are performed. They predict fast oscillations of the electronic character around the intersection of the ground and first excited diabatic states. An experiment based on high-order harmonic transient grating spectroscopy reveals dynamics occuring on the same timescale. A systematic study of the detected transient is conducted to investigate the possible influence of the pump intensity, pump wavelength, and rotational temperature of the molecules. The quantitative agreement between measured and predicted dynamics shows that, in NO2, high harmonic transient grating spectroscopy encodes vibrational dynamics underlying the electronic relaxation.

  5. Spectral analysis of the low energy Auger emission from a (0 0 0 1) ruthenium surface

    Energy Technology Data Exchange (ETDEWEB)

    Czyzewski, Jerzy J.; Krajniak, Janusz

    2003-04-30

    The low energy Auger emission from a Ru(0 0 0 1) surface have been analysed by means of a cylindrical mirror analyser (CMA) within the range of the electron energy (E) from 27 to 37 eV as a function of the primary electron energy (E{sub p}), which was set from 170 to 450 eV in 20 eV steps. Three Auger transitions at following energies: 31.7, 33.8 and 36.4 eV, have been found due to application of the backscattering generation factor idea. Obtained results for the Auger transitions were verified by means of XPS results published by Fuggle et al. [Surf. Sci. 52 (1975) 521].

  6. The Auger Engineering Radio Array and multi-hybrid cosmic ray detection

    Science.gov (United States)

    Holt, E. M.; Pierre Auger Collaboration

    2016-05-01

    The Auger Engineering Radio Array (AERA) aims at the detection of air showers induced by high-energy cosmic rays. As an extension of the Pierre Auger Observatory, it measures complementary information to the particle detectors, fluorescence telescopes and to the muon scintillators of the Auger Muons and Infill for the Ground Array (AMIGA). AERA is sensitive to all fundamental parameters of an extensive air shower such as the arrival direction, energy and depth of shower maximum. Since the radio emission is induced purely by the electromagnetic component of the shower, in combination with the AMIGA muon counters, AERA is perfect for separate measurements of the electrons and muons in the shower, if combined with a muon counting detector like AMIGA. In addition to the depth of the shower maximum, the ratio of the electron and muon number serves as a measure of the primary particle mass.

  7. Electron momentum spectroscopy of aniline taking account of nuclear dynamics in the initial electronic ground state

    Science.gov (United States)

    Farasat, M.; Shojaei, S. H. R.; Morini, F.; Golzan, M. M.; Deleuze, M. S.

    2016-04-01

    The electronic structure, electron binding energy spectrum and (e, 2e) momentum distributions of aniline have been theoretically predicted at an electron impact energy of 1.500 keV on the basis of Born-Oppenheimer molecular dynamical simulations, in order to account for thermally induced nuclear motions in the initial electronic ground state. Most computed momentum profiles are rather insensitive to thermally induced alterations of the molecular structure, with the exception of the profiles corresponding to two ionization bands at electron binding energies comprised between ˜10.0 and ˜12.0 eV (band C) and between ˜16.5 and ˜20.0 eV (band G). These profiles are found to be strongly influenced by nuclear dynamics in the electronic ground state, especially in the low momentum region. The obtained results show that thermal averaging smears out most generally the spectral fingerprints that are induced by nitrogen inversion.

  8. Electron spectroscopy at the high-energy endpoint of electron-nucleus bremsstrahlung

    Energy Technology Data Exchange (ETDEWEB)

    Hillenbrand, Pierre-Michel [GSI Darmstadt (Germany); Univ. Giessen (Germany); Hagmann, Siegbert [GSI Darmstadt (Germany); Univ. Frankfurt (Germany); Banas, Dariusz [Univ. Kielce (Poland); Brandau, Carsten [Extreme Matter Institute Darmstadt (Germany); Univ. Giessen (Germany); Doerner, Reinhard [Univ. Frankfurt (Germany); De Filippo, Enrico [INFN Catania (Italy); Gumberidze, Alexandre [Extreme Matter Institute Darmstadt (Germany); Guo, Dalong [IMP Lanzhou (China); Univ. Beijing (China); Jakubassa-Amundsen, Doris [Univ. Muenchen (Germany); Lestinsky, Michael; Spillmann, Uwe [GSI Darmstadt (Germany); Litvinov, Yuri [GSI Darmstadt (Germany); Univ. Heidelberg (Germany); Mueller, Alfred; Schippers, Stefan [Univ. Giessen (Germany); Rothard, Hermann [CIRIL GANIL Caen (France); Surzhykov, Andrey [Helmholtz-Institut Jena (Germany); Trotsenko, Sergey [GSI Darmstadt (Germany); Helmholtz-Institut Jena (Germany); Voitkiv, Alexander [MPI-K Heidelberg (Germany); Yerokhin, Vladimir [Petersburg State Univ. (Russian Federation); Stoehlker, Thomas [GSI Darmstadt (Germany); Helmholtz-Institut Jena (Germany); Univ. Jena (Germany)

    2014-07-01

    The high-energy endpoint of electron-nucleus bremsstrahlung has been studied in inverse kinematics: For collisions U{sup 88+}+N{sub 2} → U{sup 88+}+[N{sub 2}{sup +}]{sup *} + e{sup -} + γ the energy distribution of electrons scattered under θ{sub e}{sup lab} = 0 {sup circle} with v{sub e} ∼ v{sub proj} was measured coincident with the bremsstrahlung photons emitted under various angles θ{sub γ}{sup lab}. The triple-differential cross sections provide a stringent test for the fully relativistic theory of electron-nucleus bremsstrahlung. Furthermore the studied process, also termed radiative electron capture to continuum RECC, was compared to the competing processes of non-radiative electron capture to continuum ECC and the electron loss to continuum ELC.

  9. 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.

  10. Detailed theoretical and experimental description of normal Auger decay in O{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Bao Zhuo; Travnikova, Oksana; Svensson, Svante; Piancastelli, Maria Novella [Physics Department, Uppsala University, SE-75121 Uppsala (Sweden); Fink, Reinhold F [Institute of Physical Chemistry, Am Hubland, University of Wuerzburg, D-97074 Wuerzburg (Germany); Ceolin, Denis [Department of Synchrotron Radiation Research, Lund University, SE-22100 Lund (Sweden)], E-mail: Maria-Novella.Piancastelli@fysik.uu.se

    2008-06-28

    The normal Auger electron spectrum of the O{sub 2} molecule is assigned in detail on the basis of ab initio valence configuration interaction (CI) wavefunctions. Potential energy curves of the ground state, the core-ionized states and the doubly charged final states are calculated and Auger decay rates are obtained with the one-centre approximation. Using the lifetime vibrational interference method, band shapes are obtained for all contributions to the Auger spectrum. The calculated Auger electron spectrum allows us to identify all features observed experimentally. Significant differences to previous assignments are reported. A quantitative simulation of the spectrum is given on the basis of a curve-fitting procedure, in which the energetic positions and intensities of the theoretical bands were optimized. Besides providing a basis for a refined analysis of the spectrum, the fit allows us to assess the accuracy of the calculation. As expected for this level of theory, the absolute accuracy of the valence CI energies is found to be about 0.3 eV. The inherent error of the one-centre transition rates is less than 5% of the most intense transition in the spectrum. The frequently questioned one-centre Auger transition rates are shown to be rather appropriate if applied with reasonable wavefunctions and if the vibrational band structure of the molecular spectrum is properly taken into account.

  11. Electron energy loss spectroscopy in a crystalline environment using inner shell ionization

    International Nuclear Information System (INIS)

    A theory for electron energy loss spectroscopy is presented. The focus is on inner shell ionization in a crystalline environment under dynamical electron diffraction conditions which includes dechanneling due to inelastic scattering and in particular to thermal diffuse scattering (TDS). It incorporates ionization kinematics and the associated localization of the interaction from first principles. Appropriate integration over the possible final states of the detected scattered fast electron as well as the ejected target electron is catered for. The theory accounts for ionization by the dechanneled thermally scattered electrons as well as delocalization due to thermal fluctuations in target atom position. This formulation extends previous work which did not explicitly incorporate inelastic scattering into the ionization cross section. The dependence of the EELS cross section on the orientation, thickness and temperature of the specimen will be discussed. Also the influence of incident energy, energy window for the detected energy loss electrons and the acceptance angle of the detector on the cross section will be considered. In a simpler version of the formalism given here, with channeling limited to the incident electron, was successfully applied to energy dispersive x-ray emission spectroscopy and the related technique of atom location by channeling enhanced microanalysis. It is shown in this paper that this simplification is reasonable for EELS under suitable experimental conditions. 34 refs., 5 figs

  12. Measuring correlated electronic and vibrational spectral dynamics using line shapes in two-dimensional electronic-vibrational spectroscopy.

    Science.gov (United States)

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

    2015-05-01

    Two-dimensional electronic-vibrational (2DEV) spectroscopy is an experimental technique that shows great promise in its ability to provide detailed information concerning the interactions between the electronic and vibrational degrees of freedom in molecular systems. The physical quantities 2DEV is particularly suited for measuring have not yet been fully determined, nor how these effects manifest in the spectra. In this work, we investigate the use of the center line slope of a peak in a 2DEV spectrum as a measure of both the dynamic and static correlations between the electronic and vibrational states of a dye molecule in solution. We show how this center line slope is directly related to the solvation correlation function for the vibrational degrees of freedom. We also demonstrate how the strength with which the vibration on the electronic excited state couples to its bath can be extracted from a set of 2DEV spectra. These analytical techniques are then applied to experimental data from the laser dye 3,3'-diethylthiatricarbocyanine iodide in deuterated chloroform, where we determine the lifetime of the correlation between the electronic transition frequency and the transition frequency for the backbone C = C stretch mode to be ∼1.7 ps. Furthermore, we find that on the electronic excited state, this mode couples to the bath ∼1.5 times more strongly than on the electronic ground state. PMID:25956093

  13. 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.

  14. Electron spectroscopy of He and NO using electron impact and multiphoton ionisation

    International Nuclear Information System (INIS)

    This thesis describes two experimental studies which are intended to contribute to our knowledge of the structure of molecules and the decay dynamics of excited molecular states. The two studies have in common that they are both concerned with ionisation processes, in which an accurately known amount of energy is transferred to the target, and energy analysis of the ejected electrons is made. Ionisation is caused either by scattering electrons off the molecules (chapter 2: electron impact ionisation) or by a simultaneous absorption of several photons (chapter 3: multiphoton ionisation). In chapter 2 an electron impact ionisation experiment on Helium is described in which the kinematics of both the scattered and the ejected electrons is fully determined ((e,2e) experiment). (Auth.)

  15. Real-Time Probing of Electron Dynamics Using Attosecond Time-Resolved Spectroscopy

    Science.gov (United States)

    Ramasesha, Krupa; Leone, Stephen R.; Neumark, Daniel M.

    2016-05-01

    Attosecond science has paved the way for direct probing of electron dynamics in gases and solids. This review provides an overview of recent attosecond measurements, focusing on the wealth of knowledge obtained by the application of isolated attosecond pulses in studying dynamics in gases and solid-state systems. Attosecond photoelectron and photoion measurements in atoms reveal strong-field tunneling ionization and a delay in the photoemission from different electronic states. These measurements applied to molecules have shed light on ultrafast intramolecular charge migration. Similar approaches are used to understand photoemission processes from core and delocalized electronic states in metal surfaces. Attosecond transient absorption spectroscopy is used to follow the real-time motion of valence electrons and to measure the lifetimes of autoionizing channels in atoms. In solids, it provides the first measurements of bulk electron dynamics, revealing important phenomena such as the timescales governing the switching from an insulator to a metallic state and carrier-carrier interactions.

  16. Enhanced radiative Auger emission from lithiumlike 20Ca17+

    International Nuclear Information System (INIS)

    Radiative Auger emission (RAE) from lithiumlike 20Ca17+ projectiles excited in collisions with He has been measured. The intensity of RAE photons relative to Kα X-ray emission is enhanced by a factor of 10-17 compared with theoretical calculations for ions with few electron vacancies. The enhancement of RAE for Ca17+ is consistent with the results reported previously for lithiumlike 16S13+ and 23V20+ and indicates a systematic dependence on Z. Both the enhancement and the relative RAE transition rate increase with Z. (orig.)

  17. Enhanced radiative Auger emission from lithiumlike 16S13+

    International Nuclear Information System (INIS)

    The radiative Auger emission (RAE) from 0.94--6.25-MeV/u 16S13+ (lithiumlike) projectiles excited in collisions with He target atoms has been measured. For these highly stripped ions the intensity of RAE photons relative to Kα x-ray emission is enhanced by about a factor of five compared with theoretical calculations and an earlier experimental measurement for S ions with few electron vacancies. The enhancement of RAE for S13+ is qualitatively similar to results reported previously for lithiumlike 23V20+; however, some differences between S and V are evident

  18. Two-dimensional electronic spectroscopy and photosynthesis: Fundamentals and applications to photosynthetic light-harvesting

    International Nuclear Information System (INIS)

    Graphical abstract: 2D electronic spectroscopy, when combined with theoretical approaches, can investigate structure-function relationships in photosynthetic complexes by probing electronic energy transfer and excited state orientations. Display Omitted Highlights: → We review theoretical principles and experimental implementation of 2D spectroscopy. → 2DES monitors energy transfer, observes coherence, determines excited state geometry, and compares to homology models. → 2DES reveals structure-function relationships in the Photosystem II supercomplex. - Abstract: In natural light harvesting systems, pigment-protein complexes are able to harvest sunlight with near unity quantum efficiency. These complexes exhibit emergent properties that cannot be simply extrapolated from knowledge of their component parts. In this perspective, we focus on how two-dimensional electronic spectroscopy (2DES) can provide an incisive tool to probe the electronic, energetic, and spatial landscapes that must be understood to describe photosynthetic light-harvesting. We review the theoretical and experimental principles of 2DES, and demonstrate its application to the study of the Photosystem II supercomplex of green plants. We illustrate several capabilities of 2DES, including monitoring energy transfer pathways, observing excitonic coherence, determining excitonic geometry, and informing on the atomic structure.

  19. 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.

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

    Science.gov (United States)

    Dahlberg, Peter D.; Norris, Graham J.; Wang, Cheng; Viswanathan, Subha; Singh, Ved P.; Engel, Gregory S.

    2015-01-01

    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∗ states of LH2 in each of the 3 samples with a lifetime of ∼40-60 fs. PMID:26373989

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

    International Nuclear Information System (INIS)

    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∗ states of LH2 in each of the 3 samples with a lifetime of ∼40-60 fs

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

    Science.gov (United States)

    Dahlberg, Peter D.; Norris, Graham J.; Wang, Cheng; Viswanathan, Subha; Singh, Ved P.; Engel, Gregory S.

    2015-09-01

    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∗ states of LH2 in each of the 3 samples with a lifetime of ˜40-60 fs.

  3. Two-dimensional electronic spectroscopy and photosynthesis: Fundamentals and applications to photosynthetic light-harvesting

    Energy Technology Data Exchange (ETDEWEB)

    Schlau-Cohen, Gabriela S.; Ishizaki, Akihito [Department of Chemistry, University of California, Berkeley, CA 94720 (United States); Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Fleming, Graham R., E-mail: grfleming@lbl.gov [Department of Chemistry, University of California, Berkeley, CA 94720 (United States); Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States)

    2011-07-28

    Graphical abstract: 2D electronic spectroscopy, when combined with theoretical approaches, can investigate structure-function relationships in photosynthetic complexes by probing electronic energy transfer and excited state orientations. Display Omitted Highlights: {yields} We review theoretical principles and experimental implementation of 2D spectroscopy. {yields} 2DES monitors energy transfer, observes coherence, determines excited state geometry, and compares to homology models. {yields} 2DES reveals structure-function relationships in the Photosystem II supercomplex. - Abstract: In natural light harvesting systems, pigment-protein complexes are able to harvest sunlight with near unity quantum efficiency. These complexes exhibit emergent properties that cannot be simply extrapolated from knowledge of their component parts. In this perspective, we focus on how two-dimensional electronic spectroscopy (2DES) can provide an incisive tool to probe the electronic, energetic, and spatial landscapes that must be understood to describe photosynthetic light-harvesting. We review the theoretical and experimental principles of 2DES, and demonstrate its application to the study of the Photosystem II supercomplex of green plants. We illustrate several capabilities of 2DES, including monitoring energy transfer pathways, observing excitonic coherence, determining excitonic geometry, and informing on the atomic structure.

  4. 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. PMID:26899024

  5. 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. PMID:27087053

  6. 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.

  7. Detection of Nitric Oxide by Electron Paramagnetic Resonance Spectroscopy: Spin-Trapping with Iron-Dithiocarbamates.

    Science.gov (United States)

    Maia, Luisa B; Moura, José J G

    2016-01-01

    Electron paramagnetic resonance (EPR) spectroscopy is the ideal methodology to identify radicals (detection and characterization of molecular structure) and to study their kinetics, in both simple and complex biological systems. The very low concentration and short life-time of NO and of many other radicals do not favor its direct detection and spin-traps are needed to produce a new and persistent radical that can be subsequently detected by EPR spectroscopy.In this chapter, we present the basic concepts of EPR spectroscopy and of some spin-trapping methodologies to study NO. The "strengths and weaknesses" of iron-dithiocarbamates utilization, the NO traps of choice for the authors, are thoroughly discussed and a detailed description of the method to quantify the NO formation by molybdoenzymes is provided. PMID:27094413

  8. Auger neutralization and ionization in grazing ion-surface interaction

    Energy Technology Data Exchange (ETDEWEB)

    Zimny, R. (Inst. of Nuclear Physics, Univ. Muenster (Germany)); Miskovic, Z.L. (Boris Kidric Inst. of Nuclear Sciences, Belgrade (Yugoslavia))

    1991-06-01

    The effect of the projectile velocity parallel to the surface v{sub parallel} on Auger-type neutralization and ionization processes during grazing scattering of atomic particles from surfaces will be discussed. It is found that, contrary to the static case (v{sub parallel}=0), under grazing collision the Auger-type electron exchange between the metallic conduction band and an atomic orbital is a two-way process: atomic particles may be neutralized, as well as ionized. In particular, two types of v{sub parallel} dependence are obtained: (1) a gradual decrease of the final atomic level population with increasing v{sub parallel} in the case of atomic levels below the Fermi level E{sub F}, and (2) a peak-shaped v{sub parallel} dependence for atomic levels above E{sub F}. The leading features of these basic electron-exchange mechanisms between atoms and surfaces are illustrated for various atomic quasi-one-electron systems scattered from silver and magnesium surfaces. (orig.).

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

    International Nuclear Information System (INIS)

    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 Sc18+ yield a high-precision measurement of the 2s-2p3/2 transition energy in this system. Operation of the two-electron-beam setup at high collision energy (∼1000 eV) is established using resonances of hydrogenlike Mg11+, 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 F6+. (orig.)

  10. 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.)

  11. 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

  12. Analysis of catalytic gas products using electron energy-loss spectroscopy and residual gas analysis for operando transmission electron microscopy.

    Science.gov (United States)

    Miller, Benjamin K; Crozier, Peter A

    2014-06-01

    Operando transmission electron microscopy (TEM) of catalytic reactions requires that the gas composition inside the TEM be known during the in situ reaction. Two techniques for measuring gas composition inside the environmental TEM are described and compared here. First, electron energy-loss spectroscopy, both in the low-loss and core-loss regions of the spectrum was utilized. The data were quantified using a linear combination of reference spectra from individual gasses to fit a mixture spectrum. Mass spectrometry using a residual gas analyzer was also used to quantify the gas inside the environmental cell. Both electron energy-loss spectroscopy and residual gas analysis were applied simultaneously to a known 50/50 mixture of CO and CO2, so the results from the two techniques could be compared and evaluated. An operando TEM experiment was performed using a Ru catalyst supported on silica spheres and loaded into the TEM on a specially developed porous pellet TEM sample. Both techniques were used to monitor the conversion of CO to CO2 over the catalyst, while simultaneous atomic resolution imaging of the catalyst was performed. PMID:24815065

  13. 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.

  14. Application of electron paramagnetic resonance (EPR) spectroscopy and imaging in drug delivery research - chances and challenges.

    Science.gov (United States)

    Kempe, Sabine; Metz, Hendrik; Mäder, Karsten

    2010-01-01

    Electron Paramagnetic Resonance (EPR) spectroscopy is a powerful technique to study chemical species with unpaired electrons. Since its discovery in 1944, it has been widely used in a number of research fields such as physics, chemistry, biology and material and food science. This review is focused on its application in drug delivery research. EPR permits the direct measurement of microviscosity and micropolarity inside drug delivery systems (DDS), the detection of microacidity, phase transitions and the characterization of colloidal drug carriers. Additional information about the spatial distribution can be obtained by EPR imaging. The chances and also the challenges of in vitro and in vivo EPR spectroscopy and imaging in the field of drug delivery are discussed.

  15. Investigation of ageing characteristics and identification of surface chemical changes on SrGa2S4:Ce3+ display phosphor under electron beam bombardment

    International Nuclear Information System (INIS)

    Cathodoluminescent ageing characteristics of SrGa2S4:Ce3+ under prolonged electron beam bombardment was studied and the data are presented. The cathodoluminescent intensity with an increasing Coulomb loading was observed to degrade under different primary electron beam voltages. Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS) were used to monitor the surface chemical changes during electron beam bombardment and after the degradation process. Auger peak to peak heights monitored during the ageing process suggest a loss in S and C and an initial increase in oxygen concentration on the surface. XPS results indicate the formation of a SrO overlayer due to electron stimulated surface chemical reactions (ESSCRs).

  16. Techniques and Application of Electron Spectroscopy Based on Novel X-ray Sources

    OpenAIRE

    Plogmaker, Stefan

    2012-01-01

    The curiosity of researchers to find novel characteristics and properties of matter constantly pushes for the development of instrumentation based on X-radiation. I present in this thesis techniques for electron spectroscopy based on developments of X-ray sources both in time structure and energy. One part describes a laser driven High-Harmonic Generation source and the application of an off-plane grating monochromator with additional beamlines and spectrometers. In initial experiments, the s...

  17. Electron paramagnetic resonance and Raman spectroscopy studies on carbon-doped

    OpenAIRE

    Bateni, Ali; Somer, Mehmet; Erdem, Emre; Repp, Sergej; Acar, SelÇuk; Kokal, İlkin; Haessler, Wolfgang; Weber, Stefan

    2015-01-01

    Undoped and carbon-doped magnesium diboride (MgB2) samples were synthesized using two sets of mixtures prepared from the precursors, amorphous nanoboron, and as-received amorphous carbon-doped nanoboron. The microscopic defect structures of carbon-doped MgB2 samples were systematically investigated using X-ray powder diffraction, Raman and electron paramagnetic resonance spectroscopy. Mg vacancies and C-related dangling-bond active centers could be distinguished, and sp(3)-hybridized carbon r...

  18. Simulation of inelastic electron tunneling spectroscopy of single molecules with functionalized tips

    OpenAIRE

    García-Lekue, Aran; Sánchez-Portal, Daniel; Arnau, Andrés; Frederiksen, T.

    2011-01-01

    The role of the tip in inelastic electron tunneling spectroscopy (IETS) performed with scanning tunneling microscopes (STM) is theoretically addressed via first-principles simulations of vibrational spectra of single carbon monoxide (CO) molecules adsorbed on Cu(111). We show how chemically functionalized STM tips modify the IETS intensity corresponding to adsorbate modes on the sample side. The underlying propensity rules are explained using symmetry considerations for both the vibrational m...

  19. Two-dimensional electronic spectroscopy for the quantum-optics enthusiast

    OpenAIRE

    Branczyk, Agata M.; Turner, Daniel B.; Scholes, Gregory D.

    2013-01-01

    Recent interest in the role of quantum mechanics in the primary events of photosynthetic energy transfer has led to a convergence of nonlinear optical spectroscopy and quantum optics on the topic of energy-transfer dynamics in pigment-protein complexes. The convergence of these two communities has unveiled a mismatch between the background and terminology of the respective fields. To make connections, we provide a pedagogical guide to understanding the basics of two-dimensional electronic spe...

  20. Nonlinear spectroscopy of photon-dressed Dirac electrons in a quantum dot

    Science.gov (United States)

    Roslyak, O.; Gumbs, Godfrey; Mukamel, S.

    2013-01-01

    We study the localization of dressed Dirac electrons in a cylindrical quantum dot (QD) formed on monolayer and bilayer graphene by spatially different potential profiles. Short-lived excitonic states which are too broad to be resolved in linear spectroscopy are revealed by cross-peaks in the photon-echo nonlinear technique. Signatures of the dynamic gap in the two-dimensional photon-echo spectra are discussed.

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

    OpenAIRE

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

    2014-01-01

    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 fr...

  2. An Electron Energy Loss Spectroscopy Study of Metallic Nanoparticles of Gold and Silver

    OpenAIRE

    Eccles, James William Lesile

    2010-01-01

    An Electron Energy Loss Spectroscopy Study of Metallic Nanoparticles of Gold and Silver – A thesis submitted for the degree of PhDThe application of gold and silver nanoparticles to areas such as medical research is based on unique optical properties exhibited by some metals. These properties are a direct consequence of localised excitations occurring at visible frequencies known as Surface Plasmon Resonances (SPRs). The exact frequency of an SPR induced in a nanoparticle can be ‘tuned’ in ...

  3. Hyperfine interactions of 57Fe implanted in solids studied by conversion electron Moessbauer spectroscopy

    International Nuclear Information System (INIS)

    The hyperfine interactions of stable 57Fe nuclei implanted in various matrices were studied using conversion electron Moessbauer spectroscopy. The results obtained for 57Fe implanted in aluminium in d-metals in silicon and germanium are presented. The properties of the implantation produced materials and the lattice location of iron impurities are discussed. The information concerning the volume dependence of the hyperfine interactions and the origin of the electric field gradients in solids were obtained. (author)

  4. Measuring temperature in GaN-based high electron mobility transistors by cathodoluminescence spectroscopy

    International Nuclear Information System (INIS)

    In this paper, we performed a high-resolution measurement of channel temperature rise in GaN-based high electron mobility transistors (HEMTs). Cathodoluminescence spectroscopy in the scanning electron microscope was used to probe the temperature rise with several tens of nanometers spatial resolution and accuracy better than ±8 °C. We also determined the temperature distribution and peak temperature change with the power density in active AlGaN/GaN HEMTs in the source–gate and gate–drain openings. The measured results agree reasonably well with physical 2D electrothermal simulations and Raman thermography. (paper)

  5. Transformation optics: a time- and frequency-domain analysis of electron-energy loss spectroscopy

    CERN Document Server

    Kraft, Matthias; Pendry, J B

    2016-01-01

    Electron energy loss spectroscopy (EELS) and Cathodoluminescence (CL) play a pivotal role in many of the cutting edge experiments in plasmonics. EELS and CL experiments are usually supported by numerical simulations, which, whilst accurate, may not provide as much physical insight as analytical calculations do. Fully analytical solutions to EELS and CL systems in plasmonics are rare and difficult to obtain. This paper aims to narrow this gap by introducing a new method based on Transformation optics that allows to calculate the quasi-static frequency and time-domain response of plasmonic particles under electron beam excitation.

  6. 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.

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

    DEFF Research Database (Denmark)

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

    2012-01-01

    Photocatalysts are of fundamental interest for sustainable energy research [1]. By means of transmission electron microscopy (TEM), insight into the structure and composition can be obtained and used for their further optimization [2]. Here, we combine conventional TEM analysis on photocatalysts...... 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...

  8. Electronic topological transition in zinc under pressure: An x-ray absorption spectroscopy study

    Science.gov (United States)

    Aquilanti, G.; Trapananti, A.; Minicucci, M.; Liscio, F.; Twaróg, A.; Principi, E.; Pascarelli, S.

    2007-10-01

    Zinc metal has been studied at high pressure using x-ray absorption spectroscopy. In order to investigate the role of the different degrees of hydrostaticity on the occurrence of structural anomalies following the electronic topological transition, two pressure transmitting media have been used. Results show that the electronic topological transition, if it exists, does not induce an anomaly in the local environment of compressed Zn as a function of hydrostatic pressure and any anomaly must be related to a loss of hydrostaticity of the pressure transmitting medium. The near-edge structures of the spectra, sensitive to variations in the electronic density of states above the Fermi level, do not show any evidence of electronic transition whatever pressure transmitting medium is used.

  9. High resolution electron energy loss spectroscopy of narrow gap III-V semiconductor surfaces and interfaces

    CERN Document Server

    Veal, T D

    2002-01-01

    The electronic properties of n-type narrow gap III-V semiconductor surfaces and interfaces are investigated using high-resolution electron-energy-loss spectroscopy (HREELS). Changing the incident electron energy, alters the wave-vector transfer parallel to the surface, allowing the probing depth to be varied over typical space-charge layer widths (100 - 2000 A). Semi-classical dielectric theory simulations of the HREEL spectra are performed to extract quantitative information from the probing energy-dependence of the surface plasmon and phonon peaks. The plasma frequency used in the simulations is related to the electron concentration and effective mass using the Kane model of the non-parabolic conduction band. Space-charge layer parameters are obtained by comparing calculated smooth charge profiles with the histogram profiles that are used in the simulations. Complementary experimental techniques are employed to correlate the reconstruction, chemical composition and morphology of the surface with the electro...

  10. Ambient-Pressure X-ray Photoelectron Spectroscopy through Electron Transparent Graphene Membranes

    CERN Document Server

    Kraus, Jurgen; Gunther, Sebastian; Gregoratti, Luca; Amati, Matteo; Kiskinova, Maya; Yulaev, Alexander; Vlassiouk, Ivan; Kolmakov, Andrei

    2014-01-01

    Photoelectron spectroscopy (PES) and microscopy are highly demanded for exploring morphologically complex solid-gas and solid-liquid interfaces under realistic conditions, but the very small electron mean free path inside the dense media imposes serious experimental challenges. Currently, near ambient pressure PES is conducted using sophisticated and expensive electron energy analyzers coupled with differentially pumped electron lenses. An alternative economical approach proposed in this report uses ultrathin graphene membranes to isolate the ambient sample environment from the PES detection system. We demonstrate that the graphene membrane separating windows are both mechanically robust and sufficiently transparent for electrons in a wide energy range to allow PES of liquid and gaseous water. The reported proof-of-principle experiments also open a principal possibility to probe vacuum-incompatible toxic or reactive samples enclosed inside the hermetic environmental cells.

  11. 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

    2016-03-01

    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 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.

  12. Numerical simulation of Electron Energy Loss Spectroscopy using a Generalized Multipole Technique

    Energy Technology Data Exchange (ETDEWEB)

    Kiewidt, Lars [Foundation Institute of Materials Science (IWT), Department of Production Engineering, University of Bremen, Badgasteiner Str. 3, 28359 Bremen (Germany); Karamehmedović, Mirza, E-mail: mirza@iwt.uni-bremen.de [Foundation Institute of Materials Science (IWT), Department of Production Engineering, University of Bremen, Badgasteiner Str. 3, 28359 Bremen (Germany); Matyssek, Christian [Humboldt Universität zu Berlin, AG Theoretische Optik and Photonik, Newtonstr. 15, 12489 Berlin (Germany); Hergert, Wolfram [Martin Luther University Halle, Institute of Physics, Theory Group, von-Seckendorff-Platz 1, 06120 Halle (Germany); Mädler, Lutz [Foundation Institute of Materials Science (IWT), Department of Production Engineering, University of Bremen, Badgasteiner Str. 3, 28359 Bremen (Germany); Institut für Werkstofftechnik, Badgasteiner Str. 3, 28359 Bremen (Germany); Wriedt, Thomas [Institut für Werkstofftechnik, Badgasteiner Str. 3, 28359 Bremen (Germany)

    2013-10-15

    We numerically simulate low-loss Electron Energy Loss Spectroscopy (EELS) of isolated spheroidal nanoparticles, using an electromagnetic model based on a Generalized Multipole Technique (GMT). The GMT is fast and accurate, and, in principle, flexible regarding nanoparticle shape and the incident electron beam. The implemented method is validated against reference analytical and numerical methods for plane-wave scattering by spherical and spheroidal nanoparticles. Also, simulated electron energy loss (EEL) spectra of spherical and spheroidal nanoparticles are compared to available analytical and numerical solutions. An EEL spectrum is predicted numerically for a prolate spheroidal aluminum nanoparticle. The presented method is the basis for a powerful tool for the computation, analysis and interpretation of EEL spectra of general geometric configurations. - Highlights: • We simulate Electron Energy Loss Spectroscopy using a Generalized Multipole Technique. • We achieve good correspondence with reference methods for spherical nanoparticles. • The presented method is a basis for the computation and interpretation of Electron Energy Loss spectra of general geometric configurations.

  13. Electron Energy-Loss Spectroscopy: Fundamentals and applications in the characterization of minerals

    International Nuclear Information System (INIS)

    The combined use of an energy-loss spectrometer and an analytical electron microscope with fine probe forming capabilities provides a wealth of information about the sample at high spatial resolution. Fundamental principles governing the physics of the interaction between the fast electron and a thin foil sample, to account for the fine structure in the inelastically scattered fast electron distribution (Electron-Energy Loss Spectroscopy, EELS), will be reviewed. General application of EELS is in the area of low atomic number elements (Z < 11) microanalysis, where it significantly complements the more widely used Energy Dispersive X-ray Spectroscopy (EDXS). However, a careful analysis of the low loss plasmon oscillations and the fine structure in the core-loss edges, can provide additional information related to the bonding and electronic structure of the sample. An illustration of this is presented from our study of Cδ diamond residue from the Allende carbonaceous chondrite. Combination of EELS with channeling effects can provide specific site occupation/valence information in crystalline materials. Details of this novel crystallographic method will be outlined and illustrated with an example of the study of chromite spinels. Finally, some pertinent experimental details will be discussed. 7 figs

  14. Effects of the atomic level shift in the Auger neutralization rates of noble metal surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Monreal, R.C., E-mail: r.c.monreal@uam.es [Departamento de Física Teórica de la Materia Condensada and Condensed Matter Physics Centre (IFIMAC), Universidad Autónoma de Madrid, 28049 Madrid (Spain); Goebl, D.; Primetzhofer, D.; Bauer, P. [Institut für Experimentalphysik, Abteilung für Atom-und Oberflächenphysik, Johannes Kepler Universität Linz, 4040 Linz (Austria)

    2013-11-15

    In this work we compare characteristics of Auger neutralization of He{sup +} ions at noble metal and free-electron metal surfaces. For noble metals, we find that the position of the energy level of He with respect to the Fermi level has a non-negligible influence on the values of the calculated Auger rates through the evaluation of the surface dielectric susceptibility. We conclude that even though our calculated rates are accurate, further theoretical effort is needed to obtain realistic values of the energy level of He in front of these surfaces.

  15. Dynamic localization of electronic excitation in photosynthetic complexes revealed with chiral two-dimensional spectroscopy

    Science.gov (United States)

    Fidler, Andrew F.; Singh, Ved P.; Long, Phillip D.; Dahlberg, Peter D.; Engel, Gregory S.

    2014-02-01

    Time-resolved ultrafast optical probes of chiral dynamics provide a new window allowing us to explore how interactions with such structured environments drive electronic dynamics. Incorporating optical activity into time-resolved spectroscopies has proven challenging because of the small signal and large achiral background. Here we demonstrate that two-dimensional electronic spectroscopy can be adapted to detect chiral signals and that these signals reveal how excitations delocalize and contract following excitation. We dynamically probe the evolution of chiral electronic structure in the light-harvesting complex 2 of purple bacteria following photoexcitation by creating a chiral two-dimensional mapping. The dynamics of the chiral two-dimensional signal directly reports on changes in the degree of delocalization of the excitonic states following photoexcitation. The mechanism of energy transfer in this system may enhance transfer probability because of the coherent coupling among chromophores while suppressing fluorescence that arises from populating delocalized states. This generally applicable spectroscopy will provide an incisive tool to probe ultrafast transient molecular fluctuations that are obscured in non-chiral experiments.

  16. An improved approach to identify irradiated spices using electronic nose, FTIR, and EPR spectroscopy.

    Science.gov (United States)

    Sanyal, Bhaskar; Ahn, Jae-Jun; Maeng, Jeong-Hwan; Kyung, Hyun-Kyu; Lim, Ha-Kyeong; Sharma, Arun; Kwon, Joong-Ho

    2014-09-01

    Changes in cumin and chili powder from India resulting from electron-beam irradiation were investigated using 3 analytical methods: electronic nose (E-nose), Fourier transform infrared (FTIR) spectroscopy, and electron paramagnetic resonance (EPR) spectroscopy. The spices had been exposed to 6 to 14 kGy doses recommended for microbial decontamination. E-nose measured a clear difference in flavor patterns of the irradiated spices in comparison with the nonirradiated samples. Principal component analysis further showed a dose-dependent variation. FTIR spectra of the samples showed strong absorption bands at 3425, 3007 to 2854, and 1746 cm(-1). However, both nonirradiated and irradiated spice samples had comparable patterns without any noteworthy changes in functional groups. EPR spectroscopy of the irradiated samples showed a radiation-specific triplet signal at g = 2.006 with a hyper-fine coupling constant of 3 mT confirming the results obtained with the E-nose technique. Thus, E-nose was found to be a potential tool to identify irradiated spices.

  17. The Pierre Auger Cosmic Ray Observatory

    CERN Document Server

    ,

    2015-01-01

    The Pierre Auger Observatory, located on a vast, high plain in western Argentina, is the world's largest cosmic ray observatory. The objectives of the Observatory are to probe the origin and characteristics of cosmic rays above $10^{17}$ eV and to study the interactions of these, the most energetic particles observed in nature. The Auger design features an array of 1660 water-Cherenkov particle detector stations spread over 3000 km$^2$ overlooked by 24 air fluorescence telescopes. In addition, three high elevation fluorescence telescopes overlook a 23.5 km$^2$, 61 detector infill array. The Observatory has been in successful operation since completion in 2008 and has recorded data from an exposure exceeding 40,000 km$^2$ sr yr. This paper describes the design and performance of the detectors, related subsystems and infrastructure that make up the Auger Observatory.

  18. Calculations of physical and chemical reactions with DNA in aqueous solution from Auger cascades

    International Nuclear Information System (INIS)

    Monte Carlo calculations are performed of the physical and chemical interactions in liquid water by electrons produced during Auger cascades resulting from the decay of various radionuclides. Estimates are also made of the number of direct physical and indirect chemical interactions that would be produced on DNA located near the decay site. 13 refs., 8 figs

  19. A conceptual design of the set-up for solid state spectroscopy with free electron laser and insertion device radiation

    CERN Document Server

    Makhov, V N

    2001-01-01

    The set-up for complex solid state spectroscopy with the use of enhanced properties of radiation from insertion devices and free electron lasers is proposed. Very high flux and pulsed properties of radiation from insertion devices and free electron lasers offer the possibility for the use of such powerful techniques as electron paramagnetic resonance (EPR) and optically detected magnetic resonance (ODMR) for the studies of excited states of electronic excitations or defects in solids. The power density of radiation can become high enough for one more method of exited-state spectroscopy: transient optical absorption spectroscopy. The set-up is supposed to combine the EPR/ODMR spectrometer, i.e. cryostat supplied with superconducting magnet and microwave system, and the optical channels for excitation (by radiation from insertion devices or free electron laser) and detection of luminescence (i.e. primary and secondary monochromators). The set-up can be used both for 'conventional' spectroscopy of solids (reflec...

  20. Latest results from the Pierre Auger Observatory

    Science.gov (United States)

    Lhenry-Yvon, Isabelle

    2016-07-01

    The Pierre Auger Observatory has been designed to investigate the origin and nature of Ultra High Energy Cosmic Rays (UHECR) with energies from 1017 to 1020 eV. In this paper we will review some of the most recent results obtained from data of the Pierre Auger Observatory, namely the spectrum of cosmic rays, the anisotropies in arrival directions and the studies related to mass composition and to the number of muons measured at the ground. We will also discuss the implication of these results for assembling a consistent description of the composition, origin and propagation of cosmic rays.

  1. Latest results from the Pierre Auger Observatory

    Directory of Open Access Journals (Sweden)

    Lhenry-Yvon Isabelle

    2016-01-01

    Full Text Available The Pierre Auger Observatory has been designed to investigate the origin and nature of Ultra High Energy Cosmic Rays (UHECR with energies from 1017 to 1020 eV. In this paper we will review some of the most recent results obtained from data of the Pierre Auger Observatory, namely the spectrum of cosmic rays, the anisotropies in arrival directions and the studies related to mass composition and to the number of muons measured at the ground. We will also discuss the implication of these results for assembling a consistent description of the composition, origin and propagation of cosmic rays.

  2. 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....

  3. Recent progress of probing correlated electron states by point contact spectroscopy

    Science.gov (United States)

    Lee, Wei-Cheng; Greene, Laura H.

    2016-09-01

    We review recent progress in point contact spectroscopy (PCS) to extract spectroscopic information out of correlated electron materials, with the emphasis on non-superconducting states. PCS has been used to detect bosonic excitations in normal metals, where signatures (e.g. phonons) are usually less than 1% of the measured conductance. In the superconducting state, point contact Andreev reflection (PCAR) has been widely used to study properties of the superconducting gap in various superconductors. It has been well-recognized that the corresponding conductance can be accurately fitted by the Blonder-Tinkham-Klapwijk (BTK) theory in which the AR occurring near the point contact junction is modeled by three parameters; the superconducting gap, the quasiparticle scattering rate, and a dimensionless parameter, Z, describing the strength of the potential barrier at the junction. AR can be as large as 100% of the background conductance, and only arises in the case of superconductors. In the last decade, there have been more and more experimental results suggesting that the point contact conductance could reveal new features associated with the unusual single electron dynamics in non-superconducting states, shedding a new light on exploring the nature of the competing phases in correlated materials. To correctly interpret these new features, it is crucial to re-examine the modeling of the point contact junctions, the formalism used to describe the single electron dynamics particularly in point contact spectroscopy, and the physical quantity that should be computed to understand the conductance. We will summarize the theories for point contact spectroscopy developed from different approaches and highlight these conceptual differences distinguishing point contact spectroscopy from tunneling-based probes. Moreover, we will show how the Schwinger-Kadanoff-Baym-Keldysh (SKBK) formalism together with the appropriate modeling of the nano-scale point contacts randomly distributed

  4. Recent progress of probing correlated electron states by point contact spectroscopy.

    Science.gov (United States)

    Lee, Wei-Cheng; Greene, Laura H

    2016-09-01

    We review recent progress in point contact spectroscopy (PCS) to extract spectroscopic information out of correlated electron materials, with the emphasis on non-superconducting states. PCS has been used to detect bosonic excitations in normal metals, where signatures (e.g. phonons) are usually less than 1% of the measured conductance. In the superconducting state, point contact Andreev reflection (PCAR) has been widely used to study properties of the superconducting gap in various superconductors. It has been well-recognized that the corresponding conductance can be accurately fitted by the Blonder-Tinkham-Klapwijk (BTK) theory in which the AR occurring near the point contact junction is modeled by three parameters; the superconducting gap, the quasiparticle scattering rate, and a dimensionless parameter, Z, describing the strength of the potential barrier at the junction. AR can be as large as 100% of the background conductance, and only arises in the case of superconductors. In the last decade, there have been more and more experimental results suggesting that the point contact conductance could reveal new features associated with the unusual single electron dynamics in non-superconducting states, shedding a new light on exploring the nature of the competing phases in correlated materials. To correctly interpret these new features, it is crucial to re-examine the modeling of the point contact junctions, the formalism used to describe the single electron dynamics particularly in point contact spectroscopy, and the physical quantity that should be computed to understand the conductance. We will summarize the theories for point contact spectroscopy developed from different approaches and highlight these conceptual differences distinguishing point contact spectroscopy from tunneling-based probes. Moreover, we will show how the Schwinger-Kadanoff-Baym-Keldysh (SKBK) formalism together with the appropriate modeling of the nano-scale point contacts randomly distributed

  5. 30 CFR 819.15 - Auger mining: Hydrologic balance.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 3 2010-07-01 2010-07-01 false Auger mining: Hydrologic balance. 819.15... MINING § 819.15 Auger mining: Hydrologic balance. (a) Auger mining shall be planned and conducted to minimize disturbances of the prevailing hydrologic balance in accordance with the requirements of §§...

  6. 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...

  7. Nonadiabatic Dynamics May Be Probed through Electronic Coherence in Time-Resolved Photoelectron Spectroscopy.

    Science.gov (United States)

    Bennett, Kochise; Kowalewski, Markus; Mukamel, Shaul

    2016-02-01

    We present a hierarchy of Fermi golden rules (FGRs) that incorporate strongly coupled electronic/nuclear dynamics in time-resolved photoelectron spectroscopy (TRPES) signals at different levels of theory. Expansion in the joint electronic and nuclear eigenbasis yields the numerically most challenging exact FGR (eFGR). The quasistatic Fermi Golden Rule (qsFGR) neglects nuclear motion during the photoionization process but takes into account electronic coherences as well as populations initially present in the pumped matter as well as those generated internally by coupling between electronic surfaces. The standard semiclassical Fermi Golden Rule (scFGR) neglects the electronic coherences and the nuclear kinetic energy during the ionizing pulse altogether, yielding the classical Condon approximation. The coherence contributions depend on the phase-profile of the ionizing field, allowing coherent control of TRPES signals. The photoelectron spectrum from model systems is simulated using these three levels of theory. The eFGR and the qsFGR show temporal oscillations originating from the electronic or vibrational coherences generated as the nuclear wave packet traverses a conical intersection. These oscillations, which are missed by the scFGR, directly reveal the time-evolving splitting between electronic states of the neutral molecule in the curve-crossing regime. PMID:26691822

  8. Investigations into the electronic structure of the high-Tc superconductors by means of photoelectron spectroscopy

    International Nuclear Information System (INIS)

    The electronic structure of various polycrystalline samples including the new YBaCuO- and BiCaSrCuO- high Tc superconductors (HTSC) and related systems is investigated by photoelectron spectroscopy. Additional characterization is performed by conductivity measurements. In particular, the binding energy of the Cu-2p3/2- and the O-1s-levels of various HTSC is determined. For the first time the controversial 531 eV oxygen line was shown to be an intrinsic electronic structure effect. Sintered CuO-samples are obtained for the first time. The electronic structure of the sintered CuO turns out to be drastically different with respect to pressed CuO powder. For the first time a crossover resonance from a O-1s- into a Cu-3d-level was observed with synchrotron radiation. This is additional evidence for the strong hybridization between the Cu-3d and the O-2p states. Photoemission spectroscopy shows that the holes in the HTSC's are located at the oxygen p-band. Fe and Al overlayers on the HTSC-samples induce a drastic change in the electronic properties of the interface: apparently oxygen is removed from the HTSC to the overlayer. (orig./BHO)

  9. Direct characterization of the energy level alignments and molecular components in an organic hetero-junction by integrated photoemission spectroscopy and reflection electron energy loss spectroscopy analysis

    Science.gov (United States)

    Yun, Dong-Jin; Shin, Weon-Ho; Bulliard, Xavier; Park, Jong Hwan; Kim, Seyun; Chung, Jae Gwan; Kim, Yongsu; Heo, Sung; Kim, Seong Heon

    2016-08-01

    A novel, direct method for the characterization of the energy level alignments at bulk-heterojunction (BHJ)/electrode interfaces on the basis of electronic spectroscopy measurements is proposed. The home-made in situ photoemission system is used to perform x-ray/ultraviolet photoemission spectroscopy (XPS/UPS), reflection electron energy loss spectroscopy (REELS) and inverse photoemission spectroscopy of organic-semiconductors (OSCs) deposited onto a Au substrate. Through this analysis system, we are able to obtain the electronic structures of a boron subphthalocyanine chloride:fullerene (SubPC:C60) BHJ and those of the separate OSC/electrode structures (SubPC/Au and C60/Au). Morphology and chemical composition analyses confirm that the original SubPC and C60 electronic structures remain unchanged in the electrodes prepared. Using this technique, we ascertain that the position and area of the nearest peak to the Fermi energy (EF = 0 eV) in the UPS (REELS) spectra of SubPC:C60 BHJ provide information on the highest occupied molecular orbital level (optical band gap) and combination ratio of the materials, respectively. Thus, extracting the adjusted spectrum from the corresponding SubPC:C60 BHJ UPS (REELS) spectrum reveals its electronic structure, equivalent to that of the C60 materials. This novel analytical approach allows complete energy-level determination for each combination ratio by separating its electronic structure information from the BHJ spectrum.

  10. Direct characterization of the energy level alignments and molecular components in an organic hetero-junction by integrated photoemission spectroscopy and reflection electron energy loss spectroscopy analysis.

    Science.gov (United States)

    Yun, Dong-Jin; Shin, Weon-Ho; Bulliard, Xavier; Park, Jong Hwan; Kim, Seyun; Chung, Jae Gwan; Kim, Yongsu; Heo, Sung; Kim, Seong Heon

    2016-08-26

    A novel, direct method for the characterization of the energy level alignments at bulk-heterojunction (BHJ)/electrode interfaces on the basis of electronic spectroscopy measurements is proposed. The home-made in situ photoemission system is used to perform x-ray/ultraviolet photoemission spectroscopy (XPS/UPS), reflection electron energy loss spectroscopy (REELS) and inverse photoemission spectroscopy of organic-semiconductors (OSCs) deposited onto a Au substrate. Through this analysis system, we are able to obtain the electronic structures of a boron subphthalocyanine chloride:fullerene (SubPC:C60) BHJ and those of the separate OSC/electrode structures (SubPC/Au and C60/Au). Morphology and chemical composition analyses confirm that the original SubPC and C60 electronic structures remain unchanged in the electrodes prepared. Using this technique, we ascertain that the position and area of the nearest peak to the Fermi energy (EF = 0 eV) in the UPS (REELS) spectra of SubPC:C60 BHJ provide information on the highest occupied molecular orbital level (optical band gap) and combination ratio of the materials, respectively. Thus, extracting the adjusted spectrum from the corresponding SubPC:C60 BHJ UPS (REELS) spectrum reveals its electronic structure, equivalent to that of the C60 materials. This novel analytical approach allows complete energy-level determination for each combination ratio by separating its electronic structure information from the BHJ spectrum. PMID:27420635

  11. Electronic Structures of Uranium Compounds Studied by Soft X-ray Photoelectron Spectroscopy

    Science.gov (United States)

    Fujimori, Shin-ichi; Takeda, Yukiharu; Okane, Tetsuo; Saitoh, Yuji; Fujimori, Atsushi; Yamagami, Hiroshi; Haga, Yoshinori; Yamamoto, Etsuji; Ōnuki, Yoshichika

    2016-06-01

    The electronic structures of uranium-based compounds have been studied by photoelectron spectroscopy with soft X-ray synchrotron radiation. Angle-resolved photoelectron spectroscopy with soft X-rays has made it possible to directly observe their bulk band structures and Fermi surfaces. It has been shown that the band structures and Fermi surfaces of itinerant compounds such as UB2, UN, and UFeGa5 are quantitatively described by a band-structure calculation treating all U 5f electrons as itinerant. Furthermore, the overall electronic structures of heavy-fermion compounds such as UPd2Al3, UNi2Al3, and URu2Si2 are also explained by a band-structure calculation, although some disagreements exist, which might originate from the electron correlation effect. This suggests that the itinerant description of U 5f states is an appropriate starting point for the description of their electronic structures. The situation is similar for ferromagnetic superconductors such as UGe2, URhGe, UCoGe, and UIr, although the complications from their low-symmetry crystal structures make it more difficult to describe their detailed electronic structures. The local electronic structures of the uranium site have been probed by core-level photoelectron spectroscopy with soft X-rays. The comparisons of core-level spectra of heavy-fermion compounds with typical itinerant and localized compounds suggest that the local electronic structures of most itinerant and heavy-fermion compounds are close to the U 5f3 configuration except for UPd2Al3 and UPt3. The core-level spectrum of UPd2Al3 has similarities to those of both itinerant and localized compounds, suggesting that it is located at the boundary between the itinerant and localized states. Moreover, the spectrum of UPt3 is very close to that of the localized compound UPd3, suggesting that it is nearly localized, although there are narrow quasi-particle bands in the vicinity of EF.

  12. Probing plasmons in three dimensions by combining complementary spectroscopies in a scanning transmission electron microscope

    Science.gov (United States)

    Hachtel, J. A.; Marvinney, C.; Mouti, A.; Mayo, D.; Mu, R.; Pennycook, S. J.; Lupini, A. R.; Chisholm, M. F.; Haglund, R. F.; Pantelides, S. T.

    2016-04-01

    The nanoscale optical response of surface plasmons in three-dimensional metallic nanostructures plays an important role in many nanotechnology applications, where precise spatial and spectral characteristics of plasmonic elements control device performance. Electron energy loss spectroscopy (EELS) and cathodoluminescence (CL) within a scanning transmission electron microscope have proven to be valuable tools for studying plasmonics at the nanoscale. Each technique has been used separately, producing three-dimensional reconstructions through tomography, often aided by simulations for complete characterization. Here we demonstrate that the complementary nature of the two techniques, namely that EELS probes beam-induced electronic excitations while CL probes radiative decay, allows us to directly obtain a spatially- and spectrally-resolved picture of the plasmonic characteristics of nanostructures in three dimensions. The approach enables nanoparticle-by-nanoparticle plasmonic analysis in three dimensions to aid in the design of diverse nanoplasmonic applications.

  13. 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.

  14. Density measurement of thin layers by electron energy loss spectroscopy (EELS).

    Science.gov (United States)

    Thomas, Jürgen; Ramm, Jürgen; Gemming, Thomas

    2013-07-01

    A method to measure the density of thin layers is presented which utilizes electron energy loss spectroscopy (EELS) techniques within a transmission electron microscope. The method is based on the acquisition of energy filtered images in the low loss region as well as of an element distribution map using core loss edges. After correction of multiple inelastic scattering effects, the intensity of the element distribution map is proportional to density and thickness. The dependence of the intensities of images with low energy loss electrons on the density is different from that. This difference allows the calculation of the relative density pixel by pixel and to determine lateral density gradients or fluctuations in thin films without relying on a constant specimen thickness. The method is demonstrated at thin carbon layers produced with density gradients.

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

    International Nuclear Information System (INIS)

    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

  16. Electron mean free path from angle-dependent photoelectron spectroscopy of aerosol particles

    CERN Document Server

    Goldmann, Maximilian; West, Adam H C; Yoder, Bruce L; Signorell, Ruth

    2015-01-01

    We propose angle-resolved photoelectron spectroscopy of aerosol particles as an alternative way to determine the electron mean free path of low energy electrons in solid and liquid materials. The mean free path is obtained from fits of simulated photoemission images to experimental ones over a broad range of different aerosol particle sizes. The principal advantage of the aerosol approach is twofold. Firstly, aerosol photoemission studies can be performed for many different materials, including liquids. Secondly, the size-dependent anisotropy of the photoelectrons can be exploited in addition to size-dependent changes in their kinetic energy. These finite size effects depend in different ways on the mean free path and thus provide more information on the mean free path than corresponding liquid jet, thin film, or bulk data. The present contribution is a proof of principle employing a simple model for the photoemission of electrons and preliminary experimental data for potassium chloride aerosol particles.

  17. Subcellular localization of Cd in the root cells of Allium sativum by electron energy loss spectroscopy

    Indian Academy of Sciences (India)

    Donghua Liu; Ingrid Kottke

    2003-06-01

    The ultrastructural investigation of the root cells of Allium sativum L. exposed to three different concentrations of Cd (100 M, 1 mM and 10 mM) for 9 days was carried out. The results showed that Cd induced several significant ultrastructural changes – high vacuolization in cytoplasm, deposition of electron-dense material in vacuoles and nucleoli and increment of disintegrated organelles. Data from electron energy loss spectroscopy (EELS) revealed that Cd was localized in the electron-dense precipitates in the root cells treated with 10 mM Cd. High amounts of Cd were mainly accumulated in the vacuoles and nucleoli of cortical cells in differentiating and mature root tissues. The mechanisms of detoxification and tolerance of Cd are briefly explained.

  18. Electron mean free path from angle-dependent photoelectron spectroscopy of aerosol particles

    International Nuclear Information System (INIS)

    We propose angle-resolved photoelectron spectroscopy of aerosol particles as an alternative way to determine the electron mean free path of low energy electrons in solid and liquid materials. The mean free path is obtained from fits of simulated photoemission images to experimental ones over a broad range of different aerosol particle sizes. The principal advantage of the aerosol approach is twofold. First, aerosol photoemission studies can be performed for many different materials, including liquids. Second, the size-dependent anisotropy of the photoelectrons can be exploited in addition to size-dependent changes in their kinetic energy. These finite size effects depend in different ways on the mean free path and thus provide more information on the mean free path than corresponding liquid jet, thin film, or bulk data. The present contribution is a proof of principle employing a simple model for the photoemission of electrons and preliminary experimental data for potassium chloride aerosol particles

  19. Structural characterization of titania by X-ray diffraction, photoacoustic, Raman spectroscopy and electron paramagnetic resonance spectroscopy.

    Science.gov (United States)

    Kadam, R M; Rajeswari, B; Sengupta, Arijit; Achary, S N; Kshirsagar, R J; Natarajan, V

    2015-02-25

    A titania mineral (obtained from East coast, Orissa, India) was investigated by X-ray diffraction (XRD), photoacoustic spectroscopy (PAS), Raman and Electron Paramagnetic Resonance (EPR) studies. XRD studies indicated the presence of rutile (91%) and anatase (9%) phases in the mineral. Raman investigation supported this information. Both rutile and anatase phases have tetragonal structure (rutile: space group P4(2)/mnm, a=4.5946(1) Å, c=2.9597(1) Å, V=62.48(1) (Å)(3), Z=2; anatase: space group I4(1)/amd, 3.7848(2) Å, 9.5098(11) Å, V=136.22(2) (Å)(3), Z=4). The deconvoluted PAS spectrum showed nine peaks around 335, 370, 415,485, 555, 605, 659, 690,730 and 785 nm and according to the ligand field theory, these peaks were attributed to the presence of V(4+), Cr(3+), Mn(4+) and Fe(3+) species. EPR studies revealed the presence of transition metal ions V(4+)(d(1)), Cr(3+)(d(3)), Mn(4+)(d(3)) and Fe(3+)(d(5)) at Ti(4+) sites. The EPR spectra are characterized by very large crystal filed splitting (D term) and orthorhombic distortion term (E term) for multiple electron system (s>1) suggesting that the transition metal ions substitute the Ti(4+) in the lattice which is situated in distorted octahedral coordination of oxygen. The possible reasons for observation of unusually large D and E term in the EPR spectra of transition metal ions (S=3/2 and 5/2) are discussed.

  20. Chemical Distribution and Bonding of Lithium in Intercalated Graphite: Identification with Optimized Electron Energy Loss Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Y.; Wang, F.; Graetz, J.; Moreno, M.S.; Ma, C.; Wu, L.; Volkov, V.

    2011-02-01

    Direct mapping of the lithium spatial distribution and the chemical state provides critical information on structure-correlated lithium transport in electrode materials for lithium batteries. Nevertheless, probing lithium, the lightest solid element in the periodic table, poses an extreme challenge with traditional X-ray or electron scattering techniques due to its weak scattering power and vulnerability to radiation damage. Here, we report nanoscale maps of the lithium spatial distribution in electrochemically lithiated graphite using electron energy loss spectroscopy in the transmission electron microscope under optimized experimental conditions. The electronic structure of the discharged graphite was obtained from the near-edge fine structure of the Li and C K-edges and ab initio calculations. A 2.7 eV chemical shift of the Li K-edge, along with changes in the density of states, reveals the ionic nature of the intercalated lithium with significant charge transfer to the graphene sheets. Direct mapping of lithium in graphite revealed nanoscale inhomogeneities (nonstoichiometric regions), which are correlated with local phase separation and structural disorder (i.e., lattice distortion and dislocations) as observed by high-resolution transmission electron microscopy. The surface solid-electrolyte interphase (SEI) layer was also imaged and determined to have a thickness of 10-50 nm, covering both edge and basal planes with LiF as its primary inorganic component. The Li K-edge spectroscopy and mapping, combined with electron microscopy-based structural analysis provide a comprehensive view of the structure-correlated lithium intercalation in graphite and of the formation of the SEI layer.

  1. Chemical Distribution and Bonding of Lithium in Intercalated Graphite: Identification with Optimized Electron Energy Loss Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Feng [Brookhaven National Lab. (BNL), Upton, NY (United States); Graetz, Jason [Brookhaven National Lab. (BNL), Upton, NY (United States); Moreno, M. Sergio [Centro Atomico Bariloche (Argentina); Ma, Chao [Brookhaven National Lab. (BNL), Upton, NY (United States); Wu, Lijun [Brookhaven National Lab. (BNL), Upton, NY (United States); Volkov, Vyacheslav [Brookhaven National Lab. (BNL), Upton, NY (United States); Zhu, Yimei [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2011-01-10

    Direct mapping of the lithium spatial distribution and the chemical state provides critical information on structure-correlated lithium transport in electrode materials for lithium batteries. Nevertheless, probing lithium, the lightest solid element in the periodic table, poses an extreme challenge with traditional X-ray or electron scattering techniques due to its weak scattering power and vulnerability to radiation damage. Here, we report nanoscale maps of the lithium spatial distribution in electrochemically lithiated graphite using electron energy loss spectroscopy in the transmission electron microscope under optimized experimental conditions. The electronic structure of the discharged graphite was obtained from the near-edge fine structure of the Li and C K-edges and ab initio calculations. A 2.7 eV chemical shift of the Li K-edge, along with changes in the density of states, reveals the ionic nature of the intercalated lithium with significant charge transfer to the graphene sheets. Direct mapping of lithium in graphite revealed nanoscale inhomogeneities (nonstoichiometric regions), which are correlated with local phase separation and structural disorder (i.e., lattice distortion and dislocations) as observed by high-resolution transmission electron microscopy. The surface solid-electrolyte interphase (SEI) layer was also imaged and determined to have a thickness of 10-50 nm, covering both edge and basal planes with LiF as its primary inorganic component. The Li K-edge spectroscopy and mapping, combined with electron microscopy-based structural analysis provide a comprehensive view of the structure-correlated lithium intercalation in graphite and of the formation of the SEI layer.

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

    Energy Technology Data Exchange (ETDEWEB)

    Morini, Filippo; Deleuze, Michael Simon, E-mail: michael.deleuze@uhasselt.be [Center of Molecular and Materials Modelling, Hasselt University, Agoralaan Gebouw D, B-3590 Diepenbeek (Belgium); Watanabe, Noboru; Kojima, Masataka; Takahashi, Masahiko [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577 (Japan)

    2015-10-07

    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 2b{sub 1}, 6a{sub 1}, 4b{sub 2}, and 1a{sub 2} 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 A{sub 1}, B{sub 1}, and B{sub 2} 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.

  3. 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.

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

    International Nuclear Information System (INIS)

    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

  5. Highlights from the Pierre Auger Observatory

    NARCIS (Netherlands)

    Letessier-Selvon, Antoine; for the Pierre Auger Collaboration, [No Value; :, [No Value; Aab, A.; Abreu, P.; Aglietta, M.; Ahlers, M.; Ahn, E. J.; Albuquerque, I. F. M.; 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.; Antivcic, T.; Aramo, C.; Arqueros, F.; Asorey, H.; Assis, P.; Aublin, J.; Ave, M.; Avenier, M.; Avila, G.; Badescu, A. M.; Barber, K. B.; Bardenet, R.; 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.; Blumer, H.; Bohacova, M.; Boncioli, D.; Bonifazi, C.; Bonino, R.; Borodai, N.; Brack, J.; Brancus, I.; Brogueira, P.; Brown, W. C.; Buchholz, P.; Bueno, A.; Burton, R. E.; Buscemi, M.; Caballero-Mora, K. S.; Caccianiga, B.; Caccianiga, L.; Candusso, M.; Caramete, L.; Caruso, R.; Castellina, A.; Cataldi, G.; Cazon, L.; Cester, R.; Cheng, S. H.; Chiavassa, A.; Chinellato, J. A.; Chudoba, J.; Cilmo, M.; Clay, R. W.; Cocciolo, G.; Colalillo, R.; Collica, L.; Coluccia, M. R.; Conceicao, R.; Contreras, F.; Cook, H.; Cooper, M. J.; Coutu, S.; Covault, C. E.; Criss, A.; Cronin, J.; Curutiu, A.; Dallier, R.; Daniel, B.; Dasso, S.; Daumiller, K.; Dawson, B. R.; de Almeida, R. M.; De Domenico, M.; 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.; Deligny, O.; Dembinski, H.; Dhital, N.; Di Giulio, C.; Diaz, J. 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.; Ebr, J.; Engel, R.; Erdmann, M.; Escobar, C. O.; Espadanal, J.; Etchegoyen, A.; Facal San Luis, P.; Falcke, H.; Fang, K.; Farrar, G.; Fauth, A. C.; Fazzini, N.; Ferguson, A. P.; Fick, B.; Figueira, J. M.; Filevich, A.; Filipcic, A.; Foerster, N.; Fox, B. D.; Fracchiolla, C. E.; Fraenkel, E. D.; Fratu, O.; Frohlich, 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.; Glaser, C.; Glass, H.; Gomez Albarracin, F.; Gomez Berisso, M.; Gomez Vitale, P. F.; Goncalves, P.; Gonzalez, J. G.; Gookin, B.; Gorgi, A.; Gorham, P.; Gouffon, P.; Grebe, S.; Griffith, N.; Grillo, A. F.; Grubb, T. D.; 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.; Hill, G. C.; Hojvat, C.; Hollon, N.; Homola, P.; Hoerandel, J. R.; Horvath, P.; Hrabovsky, M.; Huber, D.; Huege, T.; Insolia, A.; Isar, P. G.; Jansen, S.; Jarne, C.; Josebachuili, M.; Kadija, K.; Kambeitz, O.; Kampert, K. H.; Karhan, P.; Kasper, P.; Katkov, I.; Kegl, B.; Keilhauer, B.; Keivani, A.; Kemp, E.; Kieckhafer, R. M.; Klages, H. O.; Kleifges, M.; Kleinfeller, J.; Knapp d, J.; Krause, R.; Krohm, N.; Kroemer, O.; Kruppke-Hansen, D.; Kuempel, D.; Kunka, N.; La Rosa, G.; LaHurd, D.; Latronico, L.; Lauer, R.; Lauscher, M.; Lautridou, P.; Le Coz, S.; Leao, M. S. A. B.; Lebrun, D.; Lebrun, P.; Leigui de Oliveira, M. A.; Lhenry-Yvon, I.; Link, K.; Lopez, R.; Lopez Aguera, A.; Louedec, K.; Lozano Bahilo, J.; Lu, L.; Lucero, A.; Ludwig, M.; Lyberis, H.; Maccarone, M. C.; Macolino, C.; Malacari, M.; Maldera, S.; Maller, J.; Mandat, D.; Mantsch, P.; Mariazzi, A. G.; 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, J. A. J.; Matthiae, G.; Maurel, D.; Maurizio, D.; Mayotte, E.; Mazur, P. O.; Medina, C.; Medina-Tanco, G.; Melissas, M.; Melo, D.; Menichetti, E.; Menshikov, A.; Messina, S.; Meyhandan, R.; Micanovic, S.; Micheletti, M. I.; Middendorf, L.; Minaya, I. A.; Miramonti, L.; Mitrica, B.; Molina-Bueno, L.; Mollerach, S.; Monasor, M.; Monnier Ragaigne, D.; Montanet, F.; Morales, B.; Morello, C.; Moreno, J. C.; Mostafa, M.; Moura, C. A.; Muller, M. A.; Muller, G.; Munchmeyer, 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.; Niggemann, T.; Nitz, D.; Nosek, D.; Novzka, L.; Oehlschlager, J.; Olinto, A.; Oliveira, M.; Ortiz, M.; Pacheco, N.; Pakk Selmi-Dei, D.; Palatka, M.; Pallotta, J.; Palmieri, N.; Parente, G.; 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.; Piegaia, R.; Pierog, T.; Pieroni, P.; Pimenta, M.; Pirronello, V.; Platino, M.; Plum, M.; Pontz, M.; Porcelli, A.; Preda, T.; Privitera, P.; Prouza, M.; Quel, E. J.; Querchfeld, S.; Quinn, 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 Cabo, I.; Rodriguez Fernandez, G.; 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.; Ruhle, C.; Saffi, S. J.; Saftoiu, A.; Salamida, F.; Salazar, H.; Salesa Greus, F.; Salina, G.; Sanchez, F.; Sanchez-Lucas, P.; Santo, C. E.; Santos, E.; Santos, E. M.; Sarazin, F.; Sarkar, B.; Sato, R.; Scharf, N.; Scherini, V.; Schieler, H.; Schiffer, P.; Schmidt, A.; Scholten, O.; Schoorlemmer, H.; Schovanek, P.; Schroeder, F. G.; Schulz, A.; Schulz, J.; Sciutto, S. J.; Scuderi, M.; Segreto, A.; Settimo, M.; Shadkam, A.; Shellard, R. C.; Sidelnik, I.; Sigl, G.; 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.; Straub, M.; Stutz, A.; Suarez, F.; Suomijarvi, T.; Supanitsky, A. D.; Susa, T.; Sutherland, M. S.; Swain, J.; Szadkowski, Z.; Szuba, M.; Tapia, A.; Tartare, M.; Tacscuau, O.; Tcaciuc, R.; Thao, N. T.; Tiffenberg, J.; Timmermans, C.; Tkaczyk, W.; Todero Peixoto, C. J.; Toma, G.; Tomankova, L.; Tome, B.; Tonachini, A.; Torralba Elipe, G.; Torres Machado, D.; Travnicek, P.; Tridapalli, D. B.; Trovato, E.; Tueros, M.; Ulrich, R.; Unger, M.; Valdes Galicia, J. F.; Valino, I.; Valore, L.; van Aar, G.; van den Berg, A. M.; van Velzen, S.; van Vliet, A.; Varela, E.; Vargas Cardenas, B.; Varner, G.; 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.; Wundheiler, B.; Wykes, S.; Yamamoto, T.; Yapici, T.; Younk, P.; Yuan, G.; Yushkov, A.; Zamorano, B.; Zas, E.; Zavrtanik, D.; Zavrtanik, M.; Zaw, I.; Zepeda, A.; Zhou, J.; Zhu, Y.; Zimbres Silva, M.; Ziolkowski, M.; Martin, L.

    2013-01-01

    The Pierre Auger Observatory is the world's largest cosmic ray observatory. Our current exposure reaches nearly 40,000 km$^2$ str and provides us with an unprecedented quality data set. The performance and stability of the detectors and their enhancements are described. Data analyses have led to a n

  6. Development of a single-shot CCD-based data acquisition system for time-resolved X-ray photoelectron spectroscopy at an X-ray free-electron laser facility

    International Nuclear Information System (INIS)

    A single-shot CCD-based data acquisition system for time-resolved photoelectron spectroscopy using an X-ray free-electron laser has been developed. The basic performance of the system is demonstrated using XFEL-induced and synchrotron-radiation-induced Ti 1s core-level spectroscopy. In order to utilize high-brilliance photon sources, such as X-ray free-electron lasers (XFELs), for advanced time-resolved photoelectron spectroscopy (TR-PES), a single-shot CCD-based data acquisition system combined with a high-resolution hemispherical electron energy analyzer has been developed. The system’s design enables it to be controlled by an external trigger signal for single-shot pump–probe-type TR-PES. The basic performance of the system is demonstrated with an offline test, followed by online core-level photoelectron and Auger electron spectroscopy in ‘single-shot image’, ‘shot-to-shot image (image-to-image storage or block storage)’ and ‘shot-to-shot sweep’ modes at soft X-ray undulator beamline BL17SU of SPring-8. In the offline test the typical repetition rate for image-to-image storage mode has been confirmed to be about 15 Hz using a conventional pulse-generator. The function for correcting the shot-to-shot intensity fluctuations of the exciting photon beam, an important requirement for the TR-PES experiments at FEL sources, has been successfully tested at BL17SU by measuring Au 4f photoelectrons with intentionally controlled photon flux. The system has also been applied to hard X-ray PES (HAXPES) in ‘ordinary sweep’ mode as well as shot-to-shot image mode at the 27 m-long undulator beamline BL19LXU of SPring-8 and also at the SACLA XFEL facility. The XFEL-induced Ti 1s core-level spectrum of La-doped SrTiO3 is reported as a function of incident power density. The Ti 1s core-level spectrum obtained at low power density is consistent with the spectrum obtained using the synchrotron source. At high power densities the Ti 1s core-level spectra show

  7. Electron spin resonance spectroscopy for the study of nanomaterial-mediated generation of reactive oxygen species

    Directory of Open Access Journals (Sweden)

    Weiwei He

    2014-03-01

    Full Text Available Many of the biological applications and effects of nanomaterials are attributed to their ability to facilitate the generation of reactive oxygen species (ROS. Electron spin resonance (ESR spectroscopy is a direct and reliable method to identify and quantify free radicals in both chemical and biological environments. In this review, we discuss the use of ESR spectroscopy to study ROS generation mediated by nanomaterials, which have various applications in biological, chemical, and materials science. In addition to introducing the theory of ESR, we present some modifications of the method such as spin trapping and spin labeling, which ultimately aid in the detection of short-lived free radicals. The capability of metal nanoparticles in mediating ROS generation and the related mechanisms are also presented.

  8. 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

  9. 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.

  10. Post collision interaction probed by multi-electron coincidences: Application to the Ar 2s inner-shell photoionization

    International Nuclear Information System (INIS)

    Highlights: ► We present a short review of post collision interaction (PCI), as evidenced in coincidence experiments. ► Our experiment uses synchrotron radiation and a magnetic bottle time of flight electron spectrometer. ► Emphasis is put on PCI effects occurring when inner shell ionization is followed by emission of two Auger electrons. -- Abstract: Post-collisional interaction following inner-shell ionization of atomic systems has been investigated by multi-coincidence electron spectroscopy, with a special emphasis on the decay by emission of two Auger electrons. The case of the Ar 2p hole is first reviewed. After Ar 2s inner-shell photoionization, the dominant decay channel is cascade Coster–Kronig/Auger decay. The distortion of the photoelectron peak shows a sensitivity to both the energy of the Coster–Kronig electron and to the lifetime of the intermediate Ar2+ (2p−13l−1) state that is well reproduced by a theoretical model based on the eikonal approach. The dynamics of cascade double Auger decay can be clearly understood thanks to this study.

  11. Electronic Structure of EuAl4 Studied by Photoelectron Spectroscopy

    Science.gov (United States)

    Kobata, Masaaki; Fujimori, Shin-ichi; Takeda, Yukiharu; Okane, Tetsuo; Saitoh, Yuji; Kobayashi, Keisuke; Yamagami, Hiroshi; Nakamura, Ai; Hedo, Masato; Nakama, Takao; Ōnuki, Yoshichika

    2016-09-01

    The electronic structure of the divalent Eu compound EuAl4, which shows a charge density wave transition at TCDW = 140 K, was studied by hard X-ray angle-integrated photoelectron spectroscopy (HAXPES) and soft X-ray angle-resolved photoelectron spectroscopy (ARPES). The valence band and core-level spectra obtained by HAXPES are consistent with the divalent nature of Eu atoms in EuAl4. From the ARPES results, the Fermi surface as well as band structure in the vicinity of the Fermi energy (EF) of EuAl4 are very similar to those of its isostructural divalent Sr compound SrAl4, which has no 4f electrons. This suggests that the Eu atoms are divalent in EuAl4, and the 4f electrons are localized below 1.8 eV with the Eu 4f7 electronic configuration in the ground state. The ARPES spectra measured along the Γ-(Σ)-Z high-symmetry line did not show significant temperature dependences above and below TCDW within the energy resolution of 80-90 meV. Moreover, the Fermi surface mapping along the kz direction showed that both EuAl4 and SrAl4 have mostly three-dimensional electronic structures, suggesting that the nesting of the Fermi surface is not simple. The Fermi surface and the band structure of EuAl4 were well explained by the band-structure calculation of SrAl4 based on the local density approximation.

  12. Theoretical studies of x-ray and electron core edge spectroscopies

    International Nuclear Information System (INIS)

    An understanding of the atomic architecture of matter is an essential prerequisite to a comprehension of almost any its physical and chemical properties. X-ray and electron core-edge spectroscopies are useful tools for probing both the geometric and electronic structure of matter. The full quantum mechanical multiple-scattering theory described in this dissertation is used for the interpretation of these spectroscopies, and local atomic structure determination. In this thesis, this theory is extended to treat the non-s core-state excitations. Through computer code vectorization and using proper algorithms, the multiple scattering method is capable for studying of complex systems. This method is applied to several different systems: The structure of acetylene adsorbed on Pd(111) surface, the reaction intermediate C4 H4 chemisorbed on Pd(111) surface, the Ba-doped Y2O3 catalyst, and the high temperature superconductor Bi2SrCa2Cu2O8, to investigate the effects of multiple scattering upon the absorption spectrum. The investigation on the conditions for the validity of open-quotes dipole approximationclose quotes in electron-energy loss spectroscopy (EELS) of atomic K-shell excitations on an analytic model is also presented in this thesis. A closed-form expression for the limiting magnitude qd of the momentum-transfer vector is derived. Matrix elements with many different values of q contribute to a typical EELS signal, but the dominant ones lie close to the minimum value qmin. The increase of qmin with the decrease of qd makes it easier to satisfy the conditions for the dipole approximation in the near edge rather than the extended-fine-structure region of the energy loss spectrum

  13. Direct observation of the double Auger decay of a K hole

    International Nuclear Information System (INIS)

    The double Auger (DA) decay of a K hole has been observed directly by detecting the two emitted electrons in coincidence. The hole was created in 37Cl following the electron-capture decay of 37Ar. The probability of DA decay, per Auger decay, with the two electrons both having an energy greater than 250 eV was found to be 3.7±0.2%. The DA probability was found to decrease exponentially as the energy partitioning between the two electrons changed from the asymmetric case (E1>E2) to the symmetric case (E1≅E2). The DA probability accounts for the bulk of the intensity of high charge states previously measured in 37Cl. copyright 1996 The American Physical Society

  14. Chemical interactions by low-energy electron-induced x-ray emission spectroscopy, LEXES

    CERN Document Server

    Bonnelle, C

    2002-01-01

    The possibilities presented by low-energy electron-induced x-ray emission spectroscopy to study chemical interactions in solids are discussed. Examples of change observed for the emissions between core levels as a function of the chemical environment of the emitting atoms are given. By comparing the partial densities of the valence states associated to each type of atoms in the compound, it is shown that the strength of the metal-ligand interactions can be obtained. Information on the charge densities around each type of atoms can be deduced. Application to the study of the interactions at the atomic scale to solid-solid interfaces is presented. (author)

  15. 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.

  16. 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.

  17. ZnO(0001) surfaces probed by scanning tunneling spectroscopy: Evidence for an inhomogeneous electronic structure

    Science.gov (United States)

    Dumont, J.; Hackens, B.; Faniel, S.; Mouthuy, P.-O.; Sporken, R.; Melinte, S.

    2009-09-01

    The stability of the polar Zn-terminated ZnO surface is probed by low-temperature scanning tunneling microscopy and scanning tunneling spectroscopy (STS). Surface states in the bandgap of ZnO are evidenced by STS and their presence is correlated with the local surface corrugation. Very defective surface regions are characterized by a bulk electronic structure showing a wide bandgap while nanometer-scale defect free regions exhibit a narrower bandgap and surface states. We also image atomically resolved (√3 ×√3 )R30° reconstructions on the defect-free areas.

  18. Scanning tunneling spectroscopy on ZnO(0001) surfaces : evidence for an inhomogeneous electronic structure

    Science.gov (United States)

    Hackens, B.; Rodrigues, M. S.; Faniel, S.; Mouthuy, P. O.; Melinte, S.; Dumont, J.; Sporken, R.

    2010-03-01

    We performed low temperature (77 K) scanning tunneling microscopy (STM) and spectroscopy (STS) on the polar Zn-terminated ZnO(0001) surface [1]. STM and STS data show that the surface electronic structure strongly depends on the local morphology : we observe a narrow bandgap and surface states in the flat regions, and, in the defective surface regions, a wide bandgap without surface states. We also image atomically-resolved (√3 x√3)R30^o reconstructions in small defect-free areas.[4pt] [1] J. Dumont et al., Appl. Phys. Lett. 95, 132102 (2009).

  19. Two-dimensional electronic spectroscopy for the quantum-optics enthusiast

    CERN Document Server

    Branczyk, Agata M; Scholes, Gregory D

    2013-01-01

    Recent interest in the role of quantum mechanics in the primary events of photosynthetic energy transfer has led to a convergence of nonlinear optical spectroscopy and quantum optics on the topic of energy-transfer dynamics in pigment-protein complexes. The convergence of these two communities has unveiled a mismatch between the background and terminology of the respective fields. To make connections, we provide a pedagogical guide to understanding the basics of two-dimensional electronic spectra aimed at researchers with a background in quantum optics.

  20. Broadband 2D electronic spectroscopy reveals a carotenoid dark state in purple bacteria.

    Science.gov (United States)

    Ostroumov, Evgeny E; Mulvaney, Rachel M; Cogdell, Richard J; Scholes, Gregory D

    2013-04-01

    Although the energy transfer processes in natural light-harvesting systems have been intensively studied for the past 60 years, certain details of the underlying mechanisms remain controversial. We performed broadband two-dimensional (2D) electronic spectroscopy measurements on light-harvesting proteins from purple bacteria and isolated carotenoids in order to characterize in more detail the excited-state manifold of carotenoids, which channel energy to bacteriochlorophyll molecules. The data revealed a well-resolved signal consistent with a previously postulated carotenoid dark state, the presence of which was confirmed by global kinetic analysis. The results point to this state's role in mediating energy flow from carotenoid to bacteriochlorophyll.

  1. Electron spectroscopy study of single and double multiphoton ionization of strontium by visible picosecond laser light

    OpenAIRE

    Petite, G.; Agostini, P.

    1986-01-01

    Multiphoton single and double ionization of strontium was studied using electron spectroscopy techniques. Both a picosecond, frequency doubled Nd : Yag Laser and a picosecond rhodamine 6G Dye Laser were used, with intensities ranging from 1011 W . cm- 2 to a few 10 12 W . cm-2. Single MPI was shown to produce ions in both the ground state (3 photon) and several low lying excited states, through a four photon process. Two and three photon resonances were observed, on singly and doubly excited ...

  2. Al-doped MgB2 materials studied using electron paramagnetic resonance and Raman spectroscopy

    Science.gov (United States)

    Bateni, Ali; Erdem, Emre; Repp, Sergej; Weber, Stefan; Somer, Mehmet

    2016-05-01

    Undoped and aluminum (Al) doped magnesium diboride (MgB2) samples were synthesized using a high-temperature solid-state synthesis method. The microscopic defect structures of Al-doped MgB2 samples were systematically investigated using X-ray powder diffraction, Raman spectroscopy, and electron paramagnetic resonance. It was found that Mg-vacancies are responsible for defect-induced peculiarities in MgB2. Above a certain level of Al doping, enhanced conductive properties of MgB2 disappear due to filling of vacancies or trapping of Al in Mg-related vacancy sites.

  3. Experimental and Theoretical Investigation of Valence Orbitals in 1,4-Dioxane by Electron momentum Spectroscopy

    Institute of Scientific and Technical Information of China (English)

    YANG Tie-Cheng; NING Chuan-Gang; SU Guo-Lin; DENG Jing-Kang; ZHANG Shu-Feng; REN Xue-Guang; HUANG Yan-Ru

    2006-01-01

    @@ The binding energy spectrum of all valence orbitals and the momentum distributions of highest occupied molecular orbital (HOMO: 8ag), 7bu + 7ag, 4bu, 2bg + 4ag and 2au in 1, 4-dioxane are investigated by electron momentum spectroscopy (EMS) with 600 e V impact energy. The experimental results are consistent with theoretical calculations of C2h chair conformation using the Hartree-Fock method and density functional theory with 6-311++G**and A UG-CC-PVTZ basis sets.

  4. 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 (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...

  5. Ultrafast Photo-Induced Charge Transfer Unveiled by Two-Dimensional Electronic Spectroscopy

    CERN Document Server

    Bixner, Oliver; Mancal, Tomas; Hauer, Juergen; Milota, Franz; Fischer, Michael; Pugliesi, Igor; Bradler, Maximilian; Schmid, Walther; Riedle, Eberhard; Kauffmann, Harald F; Christensson, Niklas

    2012-01-01

    The interaction of exciton and charge transfer (CT) states plays a central role in photo-induced CT processes in chemistry, biology and physics. In this work, we use a combination of two-dimensional electronic spectroscopy (2D-ES), pump-probe measurements and quantum chemistry to investigate the ultrafast CT dynamics in a lutetium bisphthalocyanine dimer in different oxidation states. It is found that in the anionic form, the combination of strong CT-exciton interaction and electronic asymmetry induced by a counter-ion enables CT between the two macrocycles of the complex on a 30 fs timescale. Following optical excitation, a chain of electron and hole transfer steps gives rise to characteristic cross-peak dynamics in the electronic 2D spectra, and we monitor how the excited state charge density ultimately localizes on the macrocycle closest to the counter-ion within 100 fs. A comparison with the dynamics in the radical species further elucidates how CT states modulate the electronic structure and tune fs-reac...

  6. 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.

  7. Determination of ground and excited state dipole moments via electronic Stark spectroscopy: 5-methoxyindole

    Energy Technology Data Exchange (ETDEWEB)

    Wilke, Josefin; Wilke, Martin; Schmitt, Michael, E-mail: mschmitt@uni-duesseldorf.de [Institut für Physikalische Chemie, Heinrich-Heine-Universität, D-40225 Düsseldorf (Germany); Meerts, W. Leo, E-mail: leo.meerts@science.ru.nl [Institute for Molecules and Materials, Radboud University, NL-6525 AS Nijmegen (Netherlands)

    2016-01-28

    The dipole moments of the ground and lowest electronically excited singlet state of 5-methoxyindole have been determined by means of optical Stark spectroscopy in a molecular beam. The resulting spectra arise from a superposition of different field configurations, one with the static electric field almost parallel to the polarization of the exciting laser radiation, the other nearly perpendicular. Each field configuration leads to different intensities in the rovibronic spectrum. With an automated evolutionary algorithm approach, the spectra can be fit and the ratio of both field configurations can be determined. A simultaneous fit of two spectra with both field configurations improved the precision of the dipole moment determination by a factor of two. We find a reduction of the absolute dipole moment from 1.59(3) D to 1.14(6) D upon electronic excitation to the lowest electronically excited singlet state. At the same time, the dipole moment orientation rotates by 54{sup ∘} showing the importance of the determination of the dipole moment components. The dipole moment in the electronic ground state can approximately be obtained from a vector addition of the indole and the methoxy group dipole moments. However, in the electronically excited state, vector addition completely fails to describe the observed dipole moment. Several reasons for this behavior are discussed.

  8. Electronic structure dynamics in a low bandgap polymer studied by time-resolved photoelectron spectroscopy.

    Science.gov (United States)

    Cappel, Ute B; Plogmaker, Stefan; Terschlüsen, Joachim A; Leitner, Torsten; Johansson, Erik M J; Edvinsson, Tomas; Sandell, Anders; Karis, Olof; Siegbahn, Hans; Svensson, Svante; Mårtensson, Nils; Rensmo, Håkan; Söderström, Johan

    2016-08-01

    Means to measure the temporal evolution following a photo-excitation in conjugated polymers are a key for the understanding and optimization of their function in applications such as organic solar cells. In this paper we study the electronic structure dynamics by direct pump-probe measurements of the excited electrons in such materials. Specifically, we carried out a time-resolved photoelectron spectroscopy (TRPES) study of the polymer PCPDTBT by combining an extreme ultraviolet (XUV) high harmonic generation source with a time-of-flight spectrometer. After excitation to either the 1st excited state or to a higher excited state, we follow how the electronic structure develops and relaxes on the electron binding energy scale. Specifically, we follow a less than 50 fs relaxation of the higher exited state and a 10 times slower relaxation of the 1st excited state. We corroborate the results using DFT calculations. Our study demonstrates the power of TRPES for studying photo-excited electron energetics and dynamics of solar cell materials. PMID:27440450

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

    Science.gov (United States)

    Verhoeven, W.; van Rens, J. F. M.; van Ninhuijs, M. A. W.; Toonen, W. F.; Kieft, E. R.; Mutsaers, P. H. A.; Luiten, O. J.

    2016-01-01

    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. PMID:27704035

  10. Electron Energy Loss Spectroscopy imaging of surface plasmons at the nanometer scale.

    Science.gov (United States)

    Colliex, Christian; Kociak, Mathieu; Stéphan, Odile

    2016-03-01

    Since their first realization, electron microscopes have demonstrated their unique ability to map with highest spatial resolution (sub-atomic in most recent instruments) the position of atoms as a consequence of the strong scattering of the incident high energy electrons by the nuclei of the material under investigation. When interacting with the electron clouds either on atomic orbitals or delocalized over the specimen, the associated energy transfer, measured and analyzed as an energy loss (Electron Energy Loss Spectroscopy) gives access to analytical properties (atom identification, electron states symmetry and localization). In the moderate energy-loss domain (corresponding to an optical spectral domain from the infrared (IR) to the rather far ultra violet (UV), EELS spectra exhibit characteristic collective excitations of the rather-free electron gas, known as plasmons. Boundary conditions, such as surfaces and/or interfaces between metallic and dielectric media, generate localized surface charge oscillations, surface plasmons (SP), which are associated with confined electric fields. This domain of research has been extraordinarily revived over the past few years as a consequence of the burst of interest for structures and devices guiding, enhancing and controlling light at the sub-wavelength scale. The present review focuses on the study of these surface plasmons with an electron microscopy-based approach which associates spectroscopy and mapping at the level of a single and well-defined nano-object, typically at the nanometer scale i.e. much improved with respect to standard, and even near-field, optical techniques. After calling to mind some early studies, we will briefly mention a few basic aspects of the required instrumentation and associated theoretical tools to interpret the very rich data sets recorded with the latest generation of (Scanning)TEM microscopes. The following paragraphs will review in more detail the results obtained on simple planar and

  11. Observing muon decays in water Cherenkov detectors at the Pierre Auger Observatory

    OpenAIRE

    Allison, P.; Arneodo, F.; Bertou, X.; Busca, N.G.; Ghia, P.L.; C. Medina; Navarra, G.; Nellen, L.; Ibarguen, H. Salazar; Ranchon, S.; Urban, M.; Villasenor, L.; Collaboration, for the Pierre Auger

    2005-01-01

    Muons decaying in the water volume of a Cherenkov detector of the Pierre Auger Observatory provide a useful calibration point at low energy. Using the digitized waveform continuously recorded by the electronics of each tank, we have devised a simple method to extract the charge spectrum of the Michel electrons, whose typical signal is about 1/8 of a crossing vertical muon. This procedure, moreover, allows continuous monitoring of the detector operation and of its water level. We have checked ...

  12. Electron Energy-Loss Spectroscopy Theory and Simulation Applied to Nanoparticle Plasmonics

    Science.gov (United States)

    Bigelow, Nicholas Walker

    In this dissertation, the capacity of electron energy-loss spectroscopy (EELS) to probe plasmons is examined in detail. EELS is shown to be able to detect both electric hot spots and Fano resonances in contrast to the prevailing knowledge prior to this work. The most detailed examination of magnetoplasmonic resonances in multi-ring structures to date and the utility of electron tomography to computational plasmonics is explored, and a new tomographic method for the reconstruction of a target is introduced. Since the observation of single-molecule surface-enhanced Raman scattering (SMSERS) in 1997, questions regarding the nature of the electromagnetic hot spots responsible for such observations still persist. A computational analysis of the electron- and photon-driven surface-plasmon resonances of monomer and dimer metal nanorods is presented to elucidate the differences and similarities between the two excitation mechanisms in a system with well understood optical properties. By correlating the nanostructure's simulated electron energy loss spectrum and loss-probability maps with its induced polarization and scattered electric field we discern how certain plasmon modes are selectively excited and how they funnel energy from the excitation source into the near- and far-field. Using a fully retarded electron-scattering theory capable of describing arbitrary three-dimensional nanoparticle geometries, aggregation schemes, and material compositions, we find that electron energy-loss spectroscopy (EELS) is able to indirectly probe the same electromagnetic hot spots that are generated by an optical excitation source. EELS is then employed in a scanning transmission electron microscope (STEM) to obtain maps of the localized surface plasmon modes of SMSERS-active nanostructures, which are resolved in both space and energy. Single-molecule character is confirmed by the bianalyte approach using two isotopologues of Rhodamine 6G. The origins of this observation are explored

  13. Characterization of deep levels in high electron mobility transistor by conductance deep level transient spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Gassoumi, M. [Laboratoire de Physique des Semiconducteurs et des Composants Electroniques Faculte des Sciences de Monastir, Avenue de l' environnement 5000 Monastir (Tunisia)], E-mail: gassoumimalek@yahoo.fr; Bluet, J.M.; Guillot, G. [Laboratoire de Physique de la Matiere (UMR CNRS 5511), INSA de Lyon, Bat. Blaise Pascal, 7 Avenue Jean Capelle, 69621 Villeurbanne Cedex (France); Gaquiere, C. [Institut d' Electronique de Microelectronique et de Nanotechnologie IEMN (TIGER), Departement hyperfrequences et Semiconducteurs, Universite des Sciences et Technologies de Lille, Avenue Poincare, 59652 Villeneuve d' Ascq Cedex (France); Maaref, H. [Laboratoire de Physique des Semiconducteurs et des Composants Electroniques Faculte des Sciences de Monastir, Avenue de l' environnement 5000 Monastir (Tunisia)], E-mail: Hassen.maaref@fsm.rnu.tn

    2008-07-01

    The influence of a substrate voltage on the dc characteristics of an AlGaN/GaN high electron mobility transistor (HEMT) on silicon (111) substrate is profited to investigate traps that are located between the substrate and the two-dimensional electron gas (2DEG) channel. The transient of the drain current after applying a negative substrate voltage is evaluated in the temperature range from 77 to 600 K. With this method, known as Conductance Deep Level Transient Spectroscopy (CDLTS), majority deep levels with activation energy of 61 meV as well as minority carrier traps at 74 meV and capture cross-section respectively 2.56 x 10{sup -15} cm{sup 2}, 2.1 x 10{sup -15} cm{sup 2} are identified. Finally, the correlation between the anomalies observed on the output characteristics and defects is discussed.

  14. Ultrafast core-loss spectroscopy in four-dimensional electron microscopy

    Directory of Open Access Journals (Sweden)

    Renske M. van der Veen

    2015-03-01

    Full Text Available We demonstrate ultrafast core-electron energy-loss spectroscopy in four-dimensional electron microscopy as an element-specific probe of nanoscale dynamics. We apply it to the study of photoexcited graphite with femtosecond and nanosecond resolutions. The transient core-loss spectra, in combination with ab initio molecular dynamics simulations, reveal the elongation of the carbon-carbon bonds, even though the overall behavior is a contraction of the crystal lattice. A prompt energy-gap shrinkage is observed on the picosecond time scale, which is caused by local bond length elongation and the direct renormalization of band energies due to temperature-dependent electron–phonon interactions.

  15. 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.

  16. Study of low-lying electronic states of ozone by anion photoelectron spectroscopy of O - 3

    Science.gov (United States)

    Arnold, Don W.; Xu, Cangshan; Kim, Eun H.; Neumark, Daniel M.

    1994-07-01

    The low-lying electronic states of ozone are studied using anion photoelectron spectroscopy of O-3. The spectra show photodetachment transitions from O-3 to the X˜ 1A1 ground state and to the five lowest lying electronic states of the ozone molecule, namely the 3A2, 3B2, 1A2, 3B1, and 1B1 states. The geometry of the ozonide anion determined from a Franck-Condon analysis of the O3 X 1A1 ground state spectrum agrees reasonably well with previous work. The excited state spectra are dominated by bending vibrational progressions which, for some states, extend well above the dissociation asymptote without noticeable lifetime broadening effects. Preliminary assignments are based upon photoelectron angular distributions and comparison with ab initio calculations. None of the excited states observed lies below the ground state dissociation limit of O3 as suggested by previous experimental and theoretical results.

  17. Electronic structure of MgB2 from angle-resolved photoemission spectroscopy.

    Science.gov (United States)

    Uchiyama, H; Shen, K M; Lee, S; Damascelli, A; Lu, D H; Feng, D L; Shen, Z-X; Tajima, S

    2002-04-15

    The first angle-resolved photoemission spectroscopy results from MgB2 single crystals are reported. Along the GammaK and GammaM directions, we observed three distinct dispersive features approaching the Fermi energy. These can be assigned to the theoretically predicted sigma (B 2p(x,y)) and pi (B 2p(z)) bands. In addition, a small parabolic-like band is detected around the Gamma point, which can be attributed to a surface-derived state. The overall agreement between our results and the band calculations suggests that the electronic structure of MgB2 is of a conventional nature, thus implying that electron correlations are weak and may be of little importance to superconductivity in this system.

  18. Determination of Surface excitation correction in elastic peak electron spectroscopy for selected conducting polymers

    Energy Technology Data Exchange (ETDEWEB)

    Lesiak, B. [Institute of Physical Chemistry Polish Academy of Sciences, 01-224 Warszawa, Kasprzaka 44/52 (Poland)]. E-mail: blo@ichf.edu.pl; Gergely, G. [Research Institute for Technical Physics and Materials Sciences, Hungarian Academy of Sciences, H-1525 Budapest, P.O. Box 49 (Hungary); Toth, J. [Nuclear Research Institute ATOMKI, H-4001 Debrecen, P.O. Box 51 (Hungary); Menyhard, M. [Research Institute for Technical Physics and Materials Sciences, Hungarian Academy of Sciences, H-1525 Budapest, P.O. Box 49 (Hungary); Varga, D. [Nuclear Research Institute ATOMKI, H-4001 Debrecen, P.O. Box 51 (Hungary); Gurban, S. [Research Institute for Technical Physics and Materials Sciences, Hungarian Academy of Sciences, H-1525 Budapest, P.O. Box 49 (Hungary); Sulyok, A. [Research Institute for Technical Physics and Materials Sciences, Hungarian Academy of Sciences, H-1525 Budapest, P.O. Box 49 (Hungary); Kosinski, A. [Institute of Physical Chemistry Polish Academy of Sciences, 01-224 Warszawa, Kasprzaka 44/52 (Poland)

    2006-12-15

    Inelastic mean free paths (IMFPs) determined by elastic peak electron spectroscopy (EPES) have been frequently evaluated neglecting surface excitations that affect the elastic peak intensity for a sample and a reference material. Surface excitation correction is defined by Surface excitation parameter, P {sub s}, denoted by SEP. SEPs for eight selected conducting polymers (polythiophenes, polyaniline and polyethylene) undoped and doped with Pd were determined by EPES using Ag, Ni and Si reference materials for electron energies between 0.2 and 2.0 keV. The mean percentage deviations between IMFPs uncorrected for surface excitations and those calculated with the predictive formulae of Gries and Tanuma et al. were 4.32 and 27.32%, respectively. Relevant deviations for IMFPs corrected for surface excitations were 2.97 and 22.90%, respectively.

  19. Influence on electron energy loss spectroscopy of the niobium-substituted uranium atom: A density functional theory study

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    We present the electronic structure and electron energy loss spectroscopy (EELS) for uranium, niobium and U3Nb in which uranium is substituted by niobium. Comparing the electronic structures and optical properties for uranium, niobium and U3Nb, we found that when niobium atom replaces uranium atom in the center lattice, density of state (DOS) of U3Nb shifts downward to low energy. Niobium affects DOS forfand d electrons more than that for p and s electrons. U3Nb is similar to uranium for the electronic energy loss spectra.

  20. Characterization of interfacially electronic structures of gold-magnetite heterostructures using X-ray absorption spectroscopy.

    Science.gov (United States)

    Lin, Fang-hsin; Doong, Ruey-an

    2014-03-01

    Gold-magnetite heterostructures are novel nanomaterials which can rapidly catalyze the reduction reaction of nitroaromatics. In this study, the interfacially structural and electronic properties of various morphologies of Au-Fe3O4 heterostructures were systematically investigated using X-ray absorbance spectroscopy (XAS) and X-ray photoelectron spectroscopy (XPS). The effect of change in electronic structure and charge transfer on electrochemically catalytic activity of Au-Fe3O4 heterostructures was further evaluated by oxygen reduction reaction (ORR). The shifts in binding energy of Au4f and Fe2p peaks in XPS spectra indicate the charge transfer between the Au and Fe3O4 nanoparticles. The increase in d-hole population of Au seeds after the conjugation with iron oxides follows the order flower-like Au-Fe3O4 (FLNPs)>dumbbell-like Au-Fe3O4 (DBNPs)>Au seeds. In addition, the Fe(2+) valence state increases in Au-Fe3O4 heterostructures, which provides evidence to support the hypothesis of charge transfer between Au and Fe3O4 nanoparticles. The theoretical simulation of Au L3-edge XAS further confirms the production of Au-Fe and Au-O bonds at the interface of Au/Fe3O4 and the epitaxial linkage relationship between Au and Fe3O4 nanoparticles. In addition, the electron deficient of Au seeds increases upon increasing Fe3O4 nanoparticles on a single Au seed, and subsequently decreases the catalytic activity of Au in the Au-Fe3O4 heterostructures. The catalytic activity of Au-Fe3O4 toward ORR follows the order Au seeds>Au-Fe3O4 DBNPs>Au-Fe3O4 FLNPs, which is positively correlated to the extent of electronic deficiency of Au in Au-Fe3O4 heterostructures.

  1. Studies of thin films and surfaces with optical harmonic generation and electron spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Wilk, D.E.

    1996-01-01

    Optical second harmonic generation (SHG) and sum frequency generation (SFG) were used to study C{sup 60} thin solid films (low energy ED forbidden electronic excitations), and electron spectroscopy was used to study organic overlayers (xylenes) on Pt(111). Theory of SHG from a thin film is described in terms of surface and bulk contributions as well as local and nonlocal contributions to the optical nonlinearities. (1)In situ SHG data on C{sub 60} films during UHV film growth can be described in terms of only nonlocal contributions to both surface and bulk nonlinear susceptibilities. Microscopic origin of SHG response is discussed in terms of electric quadrupole and ED transitions of C{sub 60}. (2)Adsorption and thermal decomposition of ortho- and para-xylene on Pt(111) is studied using HREELS, LEED, AES, and thermal desorption spectroscopy. We have observed preferential decomposition of the methyl groups which leads to distinct decomposition pathways for ortho- and para-xylene on Pt(111).

  2. Energy resolved electrochemical impedance spectroscopy for electronic structure mapping in organic semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Nádaždy, V., E-mail: nadazdy@savba.sk; Gmucová, K. [Institute of Physics SAS, Dúbravská cesta 9, 845 11 Bratislava (Slovakia); Schauer, F. [Faculty of Education, Trnava University in Trnava, 918 43 Trnava (Slovakia); Faculty of Applied Informatics, Tomas Bata University in Zlin, 760 05 Zlin (Czech Republic)

    2014-10-06

    We introduce an energy resolved electrochemical impedance spectroscopy method to map the electronic density of states (DOS) in organic semiconductor materials. The method consists in measurement of the charge transfer resistance of a semiconductor/electrolyte interface at a frequency where the redox reactions determine the real component of the impedance. The charge transfer resistance value provides direct information about the electronic DOS at the energy given by the electrochemical potential of the electrolyte, which can be adjusted using an external voltage. A simple theory for experimental data evaluation is proposed, along with an explanation of the corresponding experimental conditions. The method allows mapping over unprecedentedly wide energy and DOS ranges. Also, important DOS parameters can be determined directly from the raw experimental data without the lengthy analysis required in other techniques. The potential of the proposed method is illustrated by tracing weak bond defect states induced by ultraviolet treatment above the highest occupied molecular orbital in a prototypical σ-conjugated polymer, poly[methyl(phenyl)silylene]. The results agree well with those of our previous DOS reconstruction by post-transient space-charge-limited-current spectroscopy, which was, however, limited to a narrow energy range. In addition, good agreement of the DOS values measured on two common π-conjugated organic polymer semiconductors, polyphenylene vinylene and poly(3-hexylthiophene), with the rather rare previously published data demonstrate the accuracy of the proposed method.

  3. Gamma and electron spectroscopy of transfermium isotopes at Dubna: Results and plans

    Indian Academy of Sciences (India)

    A Yeremin; O Malyshev; A Popeko; A Lopez-Martens; K Hauschild; O Dorvaux; S Saro; D Pantelica; S Mullin

    2010-07-01

    Detailed spectroscopic information of excited nuclear states in deformed transfermium nuclei is scarce. Most of the information available today has been obtained from investigations of fine-structure -decay. Although decay gives access to hindrance factors and lifetimes which are strongly correlated to shell/subshell closures and the presence of isomers, only the combined use of and conversion electron spectroscopy allows the precise determination of excitation energy, spin and parity of nuclear levels. In the years 2004–2009 using the GABRIELA set-up [Hauschild et al, Nucl. Instrum. Methods A560, 388 (2006)] at the focal plane of VASSILISSA separator [Malyshev et al, Nucl. Instrum. Methods A440, 86 (2000); A516, 529 (2004)] experiments with the aim of and electron spectroscopy of the isotopes from Fm to Lr, formed by complete fusion reactions with accelerated heavy ions were performed. In the following, the pre- liminary results of decay studies using - and - coincidences at the focal plane of the VASSILISSA recoil separator are presented. Accumulated experience allowed us to perform ion optical calculations and to design the new experimental set-up, which will collect the base and best parameters of the existing separators and complex detector systems used at the focal planes of these installations. In the near future it is planned to study neutron-rich isotopes of the Rf–Sg in the `hot’ fusion reactions with 22Ne incident projectiles and 242Pu, 243Am and 248Cm targets.

  4. Energy resolved electrochemical impedance spectroscopy for electronic structure mapping in organic semiconductors

    Science.gov (United States)

    Nádaždy, V.; Schauer, F.; Gmucová, K.

    2014-10-01

    We introduce an energy resolved electrochemical impedance spectroscopy method to map the electronic density of states (DOS) in organic semiconductor materials. The method consists in measurement of the charge transfer resistance of a semiconductor/electrolyte interface at a frequency where the redox reactions determine the real component of the impedance. The charge transfer resistance value provides direct information about the electronic DOS at the energy given by the electrochemical potential of the electrolyte, which can be adjusted using an external voltage. A simple theory for experimental data evaluation is proposed, along with an explanation of the corresponding experimental conditions. The method allows mapping over unprecedentedly wide energy and DOS ranges. Also, important DOS parameters can be determined directly from the raw experimental data without the lengthy analysis required in other techniques. The potential of the proposed method is illustrated by tracing weak bond defect states induced by ultraviolet treatment above the highest occupied molecular orbital in a prototypical σ-conjugated polymer, poly[methyl(phenyl)silylene]. The results agree well with those of our previous DOS reconstruction by post-transient space-charge-limited-current spectroscopy, which was, however, limited to a narrow energy range. In addition, good agreement of the DOS values measured on two common π-conjugated organic polymer semiconductors, polyphenylene vinylene and poly(3-hexylthiophene), with the rather rare previously published data demonstrate the accuracy of the proposed method.

  5. Observation of UV-induced Auger features in catechol adsorbed on anatase TiO{sub 2} (101) single crystal surface

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, Andrew G. [School of Physics and Astronomy and Photon Science Institute, University of Manchester, Oxford Road, Manchester M13 9PL (United Kingdom); Syres, Karen L. [School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD (United Kingdom)

    2012-04-23

    We have investigated the electronic structure of catechol adsorbed on the anatase TiO{sub 2} (101) surface under illumination with ultraviolet (UV) light (4.75 eV) using resonant photoemission spectroscopy. UV illumination results in the appearance of a strong Ti MVV (M refers to photoionization of 3p level and VV the Auger decay process via the valence levels) feature at a kinetic energy of 26.2 eV. This is attributed to the creation of localised states following catechol to Ti-3d excitation by the UV source. A sharp resonance attributed to excitation from Ti 3p states into these localised states is observed in constant final state spectra.

  6. 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.

  7. 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 Mg2+ 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.

  8. Conformational changes of the histidine ATP-binding cassette transporter studied by double electron-electron resonance spectroscopy.

    Science.gov (United States)

    Sippach, Michael; Weidlich, Daniela; Klose, Daniel; Abé, Christoph; Klare, Johann; Schneider, Erwin; Steinhoff, Heinz-Jürgen

    2014-07-01

    The conformational dynamics of the histidine ABC transporter HisQMP2 from Salmonella enterica serovar Typhimurium, reconstituted into liposomes, is studied by site-directed spin labeling and double electron-electron resonance spectroscopy in the absence of nucleotides, in the ATP-bound, and in the post-hydrolysis state. The results show that the inter-dimer distances as measured between the Q-loops of HisP2 in the intact transporter resemble those determined for the maltose transporter in all three states of the hydrolysis cycle. Only in the presence of liganded HisJ the closed conformation of the nucleotide binding sites is achieved revealing the transmembrane communication of the presence of substrate. Two conformational states can be distinguished for the periplasmic moiety of HisQMP2 as detected by differences in distributions of interspin distances between positions 86 and 96 or 104 and 197. The observed conformational changes are correlated to proposed open, semi-open and closed conformations of the nucleotide binding domains HisP2. Our results are in line with a rearrangement of transmembrane helices 4 and 4' of HisQM during the closed to the semi-open transition of HisP2 driven by the reorientation of the coupled helices 3a and 3b to occur upon hydrolysis. PMID:24583084

  9. 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.

  10. A fast and flexible multichannel electron detector with parallel readout for photoelectron spectroscopy

    Science.gov (United States)

    Manning, P. P.; Clague, N. J.; Kirkman, I. W.; Quinn, F. M.; Hicks, P. J.

    1997-02-01

    To satisfy end user requirements for higher throughput and reliability in photoelectron spectroscopy, a new multichannel electron detector with discrete electronics has been designed and commissioned at Daresbury Laboratory. Count rate performance has been enhanced by the use of low resistance microchannel plates which amplify the electron pulses incident on the anode array. The low resistance microchannel plates are linear to 2.5 × 10 4 s -1 mm -2 for a bias voltage of 900 V per plate, providing more than an order of magnitude improvement in count rate performance over high resistance microchannel plates, microchannel plate outgassing in the ultra-high vacuum environment limits the scale of this improvement. A novel anode design maximizes the collection efficiency, while minimising crosstalk between channels (rail and electrodes on the anode. Each data collection channel comprises a fast current amplifier and discriminator, capable of a throughput of 2.5 × 10 7 s -1, and a 24 bit scaler. The integral non-linearity for flat-field illumination is better than 10% with no correction. The fast multichannel detection system gives a throughput enhancement of 10-20 on single-channel detection systems. It has also proved to be significantly better than previous multichannel detection systems with discrete electronics due to its high throughput, modular design and flexible structure.

  11. Electron transport properties of bis[2-(2-hydroxyphenyl)-pyridine]beryllium investigated by impedance spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yanping; Chen, Jiangshan; Huang, Jinying; Ma, Dongge, E-mail: mdg1014@ciac.jl.cn, E-mail: dongls@ciac.jl.cn [State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Changchun 130022 (China); Dong, Lisong, E-mail: mdg1014@ciac.jl.cn, E-mail: dongls@ciac.jl.cn [Key Laboratory of Polymer Ecomaterials, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Changchun 130022 (China); Chen, Hui [Department of Science, Shenyang University of Chemical Technology, Shenyang 110142 (China)

    2014-06-14

    The electron transport properties of bis[2-(2-hydroxyphenyl)-pyridine] beryllium (Bepp{sub 2}) are investigated by impedance spectroscopy over a frequency range of 10 Hz to 13 MHz. The Cole-Cole plots demonstrate that the Bepp{sub 2}-based device can be represented by a single parallel resistance R{sub p} and capacitance C{sub p} network with a series resistance R{sub s}. The current-voltage characteristics and the variation of R{sub p} with applied bias voltage indicate the electron conduction of space-charge-limited current with exponential trap distributions in Bepp{sub 2}. It can be seen that the electron mobility exhibits strong field-dependence in low electric field region and almost saturate in high electric field region. It is experimentally found that Bepp{sub 2} shows dispersion transport and becomes weak as the electric field increases. The activation energy is determined to be 0.043 eV by temperature-dependent conductivity, which is consistent with the result obtained from the temperature-dependent current density characteristics. The electron mobility reaches the orders of 10{sup −6}–10{sup −5} cm{sup 2} V{sup −1} s{sup −1}, depending on the electric field.

  12. The Pierre Auger Cosmic Ray Observatory

    Energy Technology Data Exchange (ETDEWEB)

    Collaboration: Pierre Auger Collaboration

    2015-10-21

    The Pierre Auger Observatory, located on a vast, high plain in western Argentina, is the world's largest cosmic ray observatory. The objectives of the Observatory are to probe the origin and characteristics of cosmic rays above 10{sup 17} eV and to study the interactions of these, the most energetic particles observed in nature. The Auger design features an array of 1660 water Cherenkov particle detector stations spread over 3000 km{sup 2} overlooked by 24 air fluorescence telescopes. In addition, three high elevation fluorescence telescopes overlook a 23.5 km{sup 2}, 61-detector infilled array with 750 m spacing. The Observatory has been in successful operation since completion in 2008 and has recorded data from an exposure exceeding 40,000 km{sup 2} sr yr. This paper describes the design and performance of the detectors, related subsystems and infrastructure that make up the Observatory.

  13. The Pierre Auger Cosmic Ray Observatory

    Science.gov (United States)

    Pierre Auger Collaboration

    2015-10-01

    The Pierre Auger Observatory, located on a vast, high plain in western Argentina, is the world's largest cosmic ray observatory. The objectives of the Observatory are to probe the origin and characteristics of cosmic rays above 1017 eV and to study the interactions of these, the most energetic particles observed in nature. The Auger design features an array of 1660 water Cherenkov particle detector stations spread over 3000 km2 overlooked by 24 air fluorescence telescopes. In addition, three high elevation fluorescence telescopes overlook a 23.5 km2, 61-detector infilled array with 750 m spacing. The Observatory has been in successful operation since completion in 2008 and has recorded data from an exposure exceeding 40,000 km2 sr yr. This paper describes the design and performance of the detectors, related subsystems and infrastructure that make up the Observatory.

  14. Valence Electronic Structure of Oxygen-Modified α-Mo2C(0001) Surface:. Angle-Resolved Photoemission Study

    Science.gov (United States)

    Kato, M.; Ozawa, K.; Sato, T.; Edamoto, K.

    Adsorption of oxygen on α-Mo2C(0001) is investigated with Auger electron spectroscopy (AES), low-energy electron diffraction (LEED) and angle-resolved photoemission spectroscopy (ARPES) utilizing synchrotron radiation. It is found that C KLL Auger peak intensity does not change during O2 exposure, indicating that the depletion of C atoms does not proceed. It is deduced from ARPES and LEED results that adsorbed oxygen atoms from a well-ordered (1 × 1) lattice on the α-Mo2C(0001) surface. The ARPES study shows that oxygen adsorption induces a peculiar state around Fermi level (EF). Off-normal-emission measurements prove that the state is a half-filled metallic state.

  15. 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.

  16. A theoretical study on UV-spectroscopy, electronic structure and reactivity properties of sesquiterpenes

    Directory of Open Access Journals (Sweden)

    S.-X. Hu

    2010-10-01

    Full Text Available Sesquiterpenes, a class of biogenic volatile organic compounds, are important precursors to secondary organic aerosols (SOAs in nature. Using density functional theory (DFT, conceptual DFT, time-dependent (TD DFT, configuration interaction with single excitation (CIS, and Zerner's intermediate neglect of differential overlap (ZINDO methods, the electronic structures, spectroscopy, and reactivity of sesquiterpenes were systematically investigated. Results from the CIS calculations show the best consistency in the excited energies and allow for assigning and predicting newly found sesquiterpenes. The results suggest that the first peaks in the ultraviolet-visible (UV-vis absorption spectra for saturated and unsaturated isomers are σ–σ* and π–π* transitions, respectively. It can be deduced from the transit intensities of the isomers that an isomer with an endocyclic C = C bond presents weaker UV transition intensity than its corresponding exocyclic isomer. The electronic structures of these compounds were also analyzed by comparing published UV-spectroscopy with advanced theoretical calculations. α-Zingiberene and longicyclene are the most and least reactive in electron-transfer reactions, respectively. No quantitative linear relationships were discovered between the changes in transit energies, DFT chemical reactivity indices of isomers, different degrees of unsaturated C = C double bonds, or the number of substituents attached to the C = C bond. The larger steric hindrance of substituents or exocyclic C = C bond is related directly to higher chemical reactivity possessed by the isomer compared to a corresponding isomer with smaller steric hindrandce or with an endo C = C bond. These results are imperative to a better understanding of SOA production mechanisms in the troposphere.

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

    Science.gov (United States)

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

    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. PMID:26429003

  18. 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.

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

    International Nuclear Information System (INIS)

    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

  20. 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.

  1. The fluorescence detector of the Pierre Auger Observatory

    Energy Technology Data Exchange (ETDEWEB)

    Abraham, J. [Universidad Tecnologica Nacional, Facultad Regional Mendoza, (UTN-FRM), Mendoza (Argentina); Abreu, P. [LIP and Instituto Superior Tecnico, Lisboa (Portugal); Aglietta, M. [Istituto di Fisica dello Spazio Interplanetario (INAF), Universita di Torino and Sezione INFN, Torino (Italy); Aguirre, C. [Universidad Catolica de Bolivia, La Paz (Bolivia, Plurinational State of); Ahn, E.J. [Fermilab, Batavia, IL (United States); Allard, D. [Laboratoire AstroParticule et Cosmologie (APC), Universite Paris 7, CNRS-IN2P3, Paris (France); Allekotte, I. [Centro Atomico Bariloche and Instituto Balseiro (CNEA-UNCuyo-CONICET), San Carlos de Bariloche (Argentina); Allen, J. [New York University, New York, NY (United States); Allison, P. [Ohio State University, Columbus, OH (United States); Alvarez-Muniz, J. [Universidad de Santiago de Compostela (Spain); Ambrosio, M. [Universita di Napoli ' Federico II' and Sezione INFN, Napoli (Italy); Anchordoqui, L. [University of Wisconsin, Milwaukee, WI (United States); Andringa, S. [LIP and Instituto Superior Tecnico, Lisboa (Portugal); Anzalone, A. [Istituto di Astrofisica Spaziale e Fisica Cosmica di Palermo (INAF), Palermo (Italy); Sezione INFN, Catania (Italy); Aramo, C. [Universita di Napoli ' Federico II' and Sezione INFN, Napoli (Italy); Arganda, E. [Universidad Complutense de Madrid, Madrid (Spain); Argiro, S. [Universita di Torino and Sezione INFN, Torino (Italy); Arisaka, K. [University of California, Los Angeles, CA (United States); Arneodo, F. [INFN, Laboratori Nazionali del Gran Sasso, Assergi , L' Aquila (Italy); Arqueros, F. [Universidad Complutense de Madrid, Madrid (Spain)

    2010-08-21

    The Pierre Auger Observatory is a hybrid detector for ultra-high energy cosmic rays. It combines a surface array to measure secondary particles at ground level together with a fluorescence detector to measure the development of air showers in the atmosphere above the array. The fluorescence detector comprises 24 large telescopes specialized for measuring the nitrogen fluorescence caused by charged particles of cosmic ray air showers. In this paper we describe the components of the fluorescence detector including its optical system, the design of the camera, the electronics, and the systems for relative and absolute calibration. We also discuss the operation and the monitoring of the detector. Finally, we evaluate the detector performance and precision of shower reconstructions.

  2. The Fluorescence Detector of the Pierre Auger Observatory

    CERN Document Server

    Abraham, J; Aglietta, M; Aguirre, C; Ahn, E J; Allard, D; Allekotte, I; Allen, J; Allison, P; Alvarez-Muñiz, J; Ambrosio, M; Anchordoqui, L; Andringa, S; Anzalone, A; Aramo, C; Arganda, E; Argirò, S; Arisaka, K; Arneodo, F; Arqueros, F; Asch, T; Asorey, H; Assis, P; Aublin, J; Ave, M; Avila, G; Bacher, A; Bäcker, T; Badagnani, D; Barber, K B; Barbosa-Ademarlaudo, F; Barbosa, H J M; Barenthien, N; Barroso, S L C; Baughman, B; Bauleo, P; Beatty, J J; Beau, T; Becker, B R; Becker, K H; Bellétoile, A; Bellido, J A; BenZvi, S; Bérat, C; Bernardini, P; Bertou, X; Biermann, P L; Billoir, P; Blanch-Bigas, O; Blanco, F; Bleve, C; Blümer, H; Boháčová, M; Bollmann, E; Bolz, H; Bonifazi, C; Bonino, R; Borodai, N; Bracci, F; Brack, J; Brogueira, P; Brown, W C; Bruijn, R; Buchholz, P; Bueno, A; Burton, R E; Busca, N G; Caballero-Mora, K S; Caramete, D CaminL; Caruso, R; Carvalho, W; Castellina, A; Castro, J; Catalano, O; Cazon, L; Cester, R; Chauvin, J; Chiavassa, A; Chinellato, J A; Chou, A; Chudoba, J; Chye, J; Clark, P D J; Clay, R W; Colombo, E; Conceição, R; Connolly, B; Contreras, F; Coppens, J; Cordero, A; Cordier, A; Cotti, U; Coutu, S; Covault, C E; Creusot, A; Criss, A; Cronin, J W; Cuautle, J; Curutiu, A; Dagoret-Campagne, S; Dallier, R; Daudo, F; Daumiller, K; Dawson, B R; de Almeida, R M; De Domenico, M; De Donato, C; De Jong, S J; De La Vega, G; Junior, W J M de Mello; Neto, J R T de Mello; De Mitri, I; De Souza, V; de Vries, K D; Decerprit, G; Del Peral, L; Deligny, O; Della Selva, A; Fratte, C Delle; Dembinski, H; Di Giulio, C; Diaz, J C; Diep, P N; Dobrigkeit, C; D'Olivo, J C; Dong, P N; Dornic, D; Dorofeev, A; Anjos, J C dos; Dova, M T; D'Urso, D; Dutan, I; Duvernois, M A; Engel, R; Erdmann, M; Escobar, C O; Etchegoyen, A; Luis, P Facal San; Falcke, H; Farrar, G; Fauth, A C; Fazzini, N; Ferrer, F; Ferrero, A; Fick, B; Filevich, A; Filipčič, A; Fleck, I; Fliescher, S; Fonte, R; Fracchiolla, C E; Fraenkel, E D; Fulgione, W; Gamarra, R F; Gambetta, S; García, B; Gámez, D García; Garcia-Pinto, D; Garrido, X; Geenen, H; Gelmini, G; Gemmeke, H; Ghia, P L; Giaccari, U; Gibbs, K; Giller, M; Gitto, J; Glass, H; Goggin, L M; Gold, M S; Golup, G; Albarracin, F Gomez; Berisso, M Gómez; Vitale, P F Gomez; Gonçalves, P; Amaral, M Gonçalves do; González, D; Gonzalez, J G; Góra, D; Gorgi, A; Gouffon, P; Grashorn, E; Grassi, V; Grebe, S; Grigat, M; Grillo, A F; Grygar, J; Guardincerri, Y; Guardone, N; Guerard, C; Guarino, F; Gumbsheimer, R; Guedes, G P; Gutiérrez, J; Hague, J D; Halenka, V; Hansen, P; Harari, D; Harmsma, S; Hartmann, S; Harton, J L; Haungs, A; Healy, M D; Hebbeker, T; Hebrero, G; Heck, D; Hojvat, C; Holmes, V C; Homola, P; Hofman, G; Hörandel, J R; Horneffer, A; Horvat, M; Hrabovský, M; Hucker, H; Huege, T; Hussain, M; Iarlori, M; Insolia, A; Ionita, F; Italiano, A; Jiraskova, S; Kaducak, M; Kampert, K H; Karova, T; Kasper, P; Kégl, B; Keilhauer, B; Kemp, E; Kern, H; Kieckhafer, R M; Klages, H O; Kleifges, M; Kleinfeller, J; Knapik, R; Knapp, J; Koang, D -H; Kopmann, A; Krieger, A; Krömer, O; Kruppke-Hansen, D; Kuempel, D; Kunka, N; Kusenko, A; La Rosa, G; Lachaud, C; Lago, B L; Lautridou, P; Leão, M S A B; Lebrun, D; Lebrun, P; Lee, J; de Oliveira, M A Leigui; Lemiere, A; Letessier-Selvon, A A; Leuthold, M; Lhenry-Yvon, I; López, R; Agüera, A Lopez; Louedec, K; Bahilo, J Lozano; Lucero, A; Lyberis, H; Maccarone, M C; Macolino, C; Maldera, S; Malek, M; Mandat, D; Mantsch, P; Marchetto, F; Mariazzi, A G; Maris, I C; Falcon, H R Marquez; Martello, D; Martineau, O; Bravo, O Martínez; Mathes, H J; Matthews, J; Matthews, J A J; Matthiae, G; Maurizio, D; Mazur, P O; McEwen, M; McNeil, R R; Medina-Tanco, G; Melissas, M; Melo, D; Menichetti, E; Menshikov, A; Meyhandan, R; Micheletti, M I; Miele, G; Miller, W; Miramonti, L; Mollerach, S; Monasor, M; Ragaigne, D Monnier; Montanet, F; Morales, B; Morello, C; Moreno, J C; Morris, C; Mostafá, M; Moura, C A; Mucchi, M; Müller, S; Muller, M A; Mussa, R; Navarra, G; Navarro, J L; Navas, S; Necesal, P; Nellen, L; Nerling, F; Newman-Holmes, C; Newton, D; Nhung, P T; Nicotra, D; Nierstenhoefer, N; Nitz, D; Nosek, D; Nožka, L; Nyklicek, M; Oehlschläger, J; Olinto, A; Oliva, P; Olmos-Gilbaja, V M; Ortiz, M; Ortolani, F; Oßwald, B; Pacheco, N; Selmi-Dei, D Pakk; Palatka, M; Pallotta, J; Parente, G; Parizot, E; Parlati, S; Pastor, S; Patel, M; Paul, T; Pavlidou, V; Payet, K; Pech, M; Pȩkala, J; Pepe, I M; Perrone, L; Pesce, R; Petermann, E; Petrera, S; Petrinca, P; Petrolini, A; Petrov, Y; Petrovic, J; Pfendner, C; Pichel, A; Piegaia, R; Pierog, T; Pimenta, M; Pinto, T; Pirronello, V; Pisanti, O; Platino, M; Pochon, J; Ponce, V H; Pontz, M; Pouryamout, J; Prado, L; Privitera, P; Prouza, M; Quel, E J; Rautenberg, G Raia J; Ravel, O; Ravignani, D; Redondo, A; Reis, H C; Reucroft, S; Revenu, B; Rezende, F A S; Rídky, J; Riggi, S; Risse, M; Rivière, C; Rizi, V; Robledo, C; Roberts, M D; Rodríguez, G; Martino, J Rodriguez; Rojo, J Rodriguez; Rodriguez-Cabo, I; Rodríguez-Frías, M D; Ros, G; Rosado, J; Rossler, T; Roth, M; Rouillé-d'Orfeuil, B; Roulet, E; Rovero, A C; Salamida, F; b, H Salazar; Salina, G; Sánchez, F; Santander, M; Santo, C E; Santos, E M; Sarazin, F; Sarkar, S; Sato, R; Scharf, N; Scherini, V; Schieler, H; Schiffer, P; Schmidt, G Schleif A; Schmidt, F; Schmidt, T; Scholten, O; Schoorlemmer, H; Schovancova, J; Schovánek, P; Schroeder, F; Schulte, S; Schüssler, F; Schuster, D; Sciutto, S J; Scuderi, M; Segreto, A; Semikoz, D; Sequieros, G; Settimo, M; Shellard, R C; Sidelnik, I; Siffert, B B; Smiałkowski, A; Šmída, R; Smith, A G K; Smith, B E; Snow, G R; Sommers, P; Sorokin, J; Spinka, H; Squartini, R; Strazzeri, E; Stutz, A; Suárez, F; Suomijärvi, T; Supanitsky, A D; Sutherland, M S; Swain, J; Szadkowski, Z; Tamashiro, A; Tamburro, A; Tarutina, T; Taşcuau, O; Tcaciuc, R; Tcherniakhovski, D; Thao, N T; Thomas, D; Ticona, R; Tiffenberg, J; Timmermans, C; Tkaczyk, W; Peixoto, C J Todero; Tomé, B; Tonachini, A; Torres, I; Trapani, P; Travnicek, P; Tridapalli, D B; Tristram, G; Trovato, E; Tuci, V; Tueros, M; Tusi, E; Ulrich, R; Unger, M; Urban, M; Galicia, J F Valdés; Valiño, I; Valore, L; Berg, A M van den; Vázquez, J R; Vázquez, R A; Veberič, D; Velarde, A; Venters, T; Verzi, V; Videla, M; Villaseñor, L; Vitali, G; Vorobiov, S; Voyvodic, L; Wahlberg, H; Wahrlich, P; Wainberg, O; Warner, D; Westerhoff, S; Whelan, B J; Wild, N; Wiebusch, C; Wieczorek, G; Wiencke, L; Wilczyńska, B; Wilczyński, H; Wileman, C; Winnick, M G; Wörner, G; Wu, H; Wundheiler, B; Yamamoto, T; Younk, P; Yuan, G; Yushkov, A; Zas, E; Zavrtanik, D; Zavrtanik, M; Zaw, I; b, A Zepeda; Ziolkowski, M

    2009-01-01

    The Pierre Auger Observatory is a hybrid detector for ultra-high energy cosmic rays. It combines a surface array to measure secondary particles at ground level together with a fluorescence detector to measure the development of air showers in the atmosphere above the array. The fluorescence detector comprises 24 large telescopes specialized for measuring the nitrogen fluorescence caused by charged particles of cosmic ray air showers. In this paper we describe the components of the fluorescence detector including its optical system, the design of the camera, the electronics, and the systems for relative and absolute calibration. We also discuss the operation and the monitoring of the detector. Finally, we evaluate the detector performance and precision of shower reconstructions.

  3. Education and Outreach for the Pierre Auger Observatory

    CERN Document Server

    Snow, Gregory R

    2007-01-01

    The scale and scope of the physics studied at the Auger Observatory offer significant opportunities for original outreach work. Education, outreach, and public relations of the Auger collaboration are coordinated in a task of its own whose goals are to encourage and support a wide range of efforts that link schools and the public with the Auger scientists and the science of cosmic rays, particle physics, and associated technologies. This report focuses on the impact of the collaboration in Mendoza Province, Argentina, as: the Auger Visitor Center in Malargue that has hosted over 29,000 visitors since 2001, the Auger Celebration and a collaboration-sponsored science fair held on the Observatory campus in November 2005, the opening of the James Cronin School in Malargue in November 2006, public lectures, school visits, and courses for science teachers. As the collaboration prepares the proposal for the northern Auger site foreseen to be in southeast Colorado, plans for a comprehensive outreach program are being...

  4. Many-body effects in the electron spectroscopies of incompletely filled bands

    International Nuclear Information System (INIS)

    Photoemission and Auger line shapes from almost completely filled bands have been widely discussed in recent years within a simplified model based on an Anderson Hamiltonian in which the virtual level shift due to the interactions is suitably compensated for. Up to now, the theory has been much more succesful with XPS than with AES, and the reason for this was obscured by the lack of an exact solution and by the difficulty to assess the degree of validity of various approximate treatments that have been proposed. Here it is presented a Green's function formalism that allows us to extend the closed band solution to the partially occupied case and lends itself to the exact numerical treatment of finite systems. By applying the theory to 27 and 125 atom cluster, it is analysed the dependance of the spectra on hole-hole repulsion U with a degree of unfilling nh≤0.25. It is also considered the case when one of the spin subbands is full as a rough model for ferromagnetic metals. Correlation effects on the one-hole density of states produce a narrowing of the band region, while a split-off structure develops below the band for U comparable to the band width. The low-density approximation is in a good agreement with the exact results for nh = 0.1 and also for nh = 0.25 for small and moderate U. Our results on the Auger line shapes justify somewhat the suggestion by Haak and Bennet et al. that split-off states observed in photoemission must be discarded before computing the two-hole spectrum. Indeed self-energy correlations must be excluded also in bandlike cases, when the simple procedure of cutting off the unwanted structure is not applicable. This arises because, in wide range of physical situations, the Auger line shape reflects the mutual scattering of undressed final-state holes

  5. Electron irradiation effect of polyurethane using coincidence doppler-broadening spectroscopy

    International Nuclear Information System (INIS)

    Full text: To understand the electron irradiation effects on polymer, polyether-urethane (ETPU) samples of 2mm in thickness and 10mm in diameter were irradiated by a 1.8MeV electron beam with beam current of 3 ma at room temperature. The irradiated doses are 5 kGy, 10 kGy, 15 kGy, 30 kGy, 100 kGy and 150 kGy. ETPU was manufactured by mixing PTMG-100, TDI-100 and MOCA. The momentum density distributions (MMDs) of electrons taking part in the annihilation processes of positron-electron pairs in ETPU have been measured by coincidence Doppler-broadening spectroscopy (CDBS). By presenting the ratio of the counts in every channel of the measured CDB spectrum to the corresponding counts from a reference spectrum (pristine ETPU), we observed that the change in MMDs is not significant for doses lower than 10 kGy. However, high momentum part of MMDs exhibit an obvious decrease for dose exceeding 15 kGy and then slowly down to steady with doses until 150 kGy. This valley occurs at around 15x103mοc and is well known as oxygen-specific, indicative of a less positron trapping by oxygen atoms in some samples of higher dose radiation. It is postulated that the radiation will break the crosslinkings, allowing the trace water and oxygen molecules to be released from the sample surface. Excess NCO groups in ETPU would crosslink with urethane and urea groups to produce allophanate and biuret groups. After receiving a certain amount of electron irradiation, crosslinked allophanate and biuret groups would produce degradation. Thus, residual water and oxygen trapped in ETPU by the crosslinking would diffuse out. However, the irradiation doses up to 150 kGy in this experiment are still not large enough to induce strong degradation of urethane and urea groups

  6. 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.

  7. Determination of Elemental Ratio in an Atomic Column by Electron Energy Loss Spectroscopy.

    Science.gov (United States)

    Haruta, Mitsutaka; Hosaka, Yoshiteru; Ichikawa, Noriya; Saito, Takashi; Shimakawa, Yuichi; Kurata, Hiroki

    2016-07-26

    Atomic-resolution quantification of the elemental ratio of Fe to Mn at the octahedral and tetrahedral sites in brownmillerite Ca2Fe1.07Mn0.93O5 was determined using electron energy-loss spectroscopy combined with aberration-corrected scanning transmission electron microscopy. The combined techniques revealed that oversampling of the spectral imaging data yielded a spatially resolved area that very nearly reflects atomic resolution (∼1.2 Å radius). The average experimental ratios of Fe to Mn within this region were 17.5:82.5 for the octahedral sites and 81.6:18.4 for the tetrahedral sites. The elemental ratio in an octahedral atomic column was successfully extracted by estimating the mixing of signals from nearest neighbor columns. The results indicated that the ratio of Fe to Mn was 13:87 at the octahedral site, which is in good agreement with the results of neutron diffraction analysis. In addition, the uncertainty of experimental results obtained by using an average 1.2 Å radius was less than 10% at octahedral sites, depending on the sample thickness. In contrast, the experimental error due to dechanneling of incident electrons was larger at the tetrahedral sites. This experimental procedure has wide application for determining the spatially resolved composition ratio of elements in perovskite-like compounds. PMID:27341006

  8. Toward 10 meV electron energy-loss spectroscopy resolution for plasmonics.

    Science.gov (United States)

    Bellido, Edson P; Rossouw, David; Botton, Gianluigi A

    2014-06-01

    Energy resolution is one of the most important parameters in electron energy-loss spectroscopy. This is especially true for measurement of surface plasmon resonances, where high-energy resolution is crucial for resolving individual resonance peaks, in particular close to the zero-loss peak. In this work, we improve the energy resolution of electron energy-loss spectra of surface plasmon resonances, acquired with a monochromated beam in a scanning transmission electron microscope, by the use of the Richardson-Lucy deconvolution algorithm. We test the performance of the algorithm in a simulated spectrum and then apply it to experimental energy-loss spectra of a lithographically patterned silver nanorod. By reduction of the point spread function of the spectrum, we are able to identify low-energy surface plasmon peaks in spectra, more localized features, and higher contrast in surface plasmon energy-filtered maps. Thanks to the combination of a monochromated beam and the Richardson-Lucy algorithm, we improve the effective resolution down to 30 meV, and evidence of success up to 10 meV resolution for losses below 1 eV. We also propose, implement, and test two methods to limit the number of iterations in the algorithm. The first method is based on noise measurement and analysis, while in the second we monitor the change of slope in the deconvolved spectrum.

  9. Surface energy loss processes in XPS studied by absolute reflection electron energy loss spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Nagatomi, T., E-mail: nagatomi@mls.eng.osaka-u.ac.j [Department of Material and Life Science, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871 (Japan); Goto, K. [National Institute of Advanced Industrial Science and Technology (AIST) Chubu, Moriyama-ku, Nagoya, Aichi 463-8560 (Japan)

    2010-05-15

    The results of the investigation of the inelastic interaction of 300-3000 eV electrons with the Ni and Au surfaces by the analysis of absolute reflection electron energy loss spectroscopy (REELS) spectra were described. The present analysis enables the inelastic mean free path (IMFP), surface excitation parameter (SEP) and differential SEP (DSEP) to be obtained simultaneously from an absolute REELS spectrum. The obtained IMFPs for Ni and Au showed a good agreement with those calculated using the TPP-2M predictive equation. The present SEPs determined for Ni and Au were fitted to the Chen's formula describing the dependence of the SEP on the electron energy, and material parameters for Ni and Au in Chen's formula were proposed. The present DESPs were compared with the theoretical results, and a reasonable agreement between the experimentally determined DSEPs and theoretical results was confirmed. The MC modeling of calculating the REELS spectrum, in which energy loss processes due to surface excitations are taken into account, was also described. The IMFP, SEP and DSEP determined by the present absolute REELS analysis were employed to describe energy loss processes by inelastic scattering in the proposed MC simulation. The simulated REELS spectra were found to be in a good agreement with the experimental spectra for both Ni and Au.

  10. Operando electron paramagnetic resonance spectroscopy – formation of mossy lithium on lithium anodes during charge–discharge cycling

    OpenAIRE

    Wandt, Johannes; Marino, Cyril; Gasteiger, Hubert A.; Jakes, Peter; Eichel, Rüdiger-A.; Granwehr, Josef

    2015-01-01

    The formation of mossy lithium and lithium dendrites so far prevents the use of lithium metal anodes in lithium ion batteries. To develop solutions for this problem (e.g., electrolyte additives), operando measurement techniques are required to monitor mossy lithium and dendrite formation during electrochemical cycling. Here we present a novel battery cell design that enables operando electron paramagnetic resonance (EPR) spectroscopy. It is shown that time-resolved operando EPR spectroscopy d...

  11. 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. PMID:17054352

  12. Raman Spectroscopy of InAs Based Nanowires & Electronic Characterization of Heterostructure InAs/GaInAs Nanowires

    DEFF Research Database (Denmark)

    Tanta, Rawa

    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......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...

  13. Calibration and Monitoring of the Pierre Auger Observatory

    CERN Document Server

    Abraham, J; Aglietta, M; Aguirre, C; Ahn, E J; Allard, D; Allekotte, I; Allen, J; Alvarez-Muñiz, J; Ambrosio, M; Anchordoqui, L; Andringa, S; Anzalone, A; Aramo, C; Arganda, E; Argirò, S; Arisaka, K; Arneodo, F; Arqueros, F; Asch, T; Asorey, H; Assis, P; Aublin, J; Ave, M; Avila, G; Bäcker, T; Badagnani, D; Barber, K B; Barbosa-Ademarlaudo, F; Barroso, S L C; Baughman, B; Bauleo, P; Beatty, J J; Beau, T; Becker, B R; Becker, K H; Bellétoile, A; Bellido, J A; BenZvi, S; Bérat, C; Bernardini, P; Bertou, X; Biermann, P L; Billoir, P; Blanch-Bigas, O; Blanco, F; Bleve, C; Blümer, H; Boháčová, M; Boncioli, D; Bonifazi, C; Bonino, R; Borodai, N; Brack, J; Brogueira, P; Brown, W C; Bruijn, R; Buchholz, P; Bueno, A; Burton, R E; Busca, N G; Caballero-Mora, K S; Caramete, L; Caruso, R; Carvalho, W; Castellina, A; Catalano, O; Cazon, L; Cester, R; Chauvin, J; Chiavassa, A; Chinellato, J A; Chou, A; Chudoba, J; Chye, J; Clay, R W; Colombo, E; Conceição, R; Connolly, B; Contreras, F; Coppens, J; Cordier, A; Cotti, U; Coutu, S; Covault, C E; Creusot, A; Criss, A; Cronin, J; Curutiu, A; Dagoret-Campagne, S; Dallier, R; Daumiller, K; Dawson, B R; de Almeida, R M; De Domenico, M; De Donato, C; De Jong, S J; De La Vega, G; Junior, W J M de Mello; Neto, J R T de Mello; De Mitri, I; De Souza, V; de Vries, K D; Decerprit, G; Del Peral, L; Deligny, O; Della Selva, A; Fratte, C Delle; Dembinski, H; DiGiulio, C; Diaz, J C; Diep, P N; Dobrigkeit, C; D'Olivo, J C; Dong, P N; Dorofeev, A; Anjos, J C dos; Dova, M T; D'Urso, D; Dutan, I; Duvernois, M A; Engel, R; Erdmann, M; Escobar, C O; Etchegoyen, A; Luis, P Facal San; Falcke, H; Farrar, G; Fauth, A C; Fazzini, N; Ferrer, F; Ferrero, A; Fick, B; Filevich, A; Filipčič, A; Fleck, I; Fliescher, S; Fracchiolla, C E; Fraenkel, E D; Fulgione, W; Gamarra, R F; Gambetta, S; García, B; GarcíaGámez, D; Garcia-Pinto, D; Garrido, X; Gelmini, G; Gemmeke, H; Ghia, P L; Giaccari, U; Giller, M; Glass, H; Goggin, L M; Gold, M S; Golup, G; Albarracin, F Gomez; Berisso, M Gómez; Gonçalves, P; Amaral, M Gonçalves do; González, D; Gonzalez, J G; Góra, D; Gorgi, A; Gouffon, P; Gozzini, S R; Grashorn, E; Grebe, S; Grigat, M; Grillo, A F; Guardincerri, Y; Guarino, F; Guedes, G P; Gutiérrez, J; Hague, J D; Halenka, V; Hansen, P; Harari, D; Harmsma, S; Harton, J L; Haungs, A; Healy, M D; Hebbeker, T; Hebrero, G; Heck, D; Hojvat, C; Holmes, V C; Homola, P; Hörandel, J R; Horneffer, A; Hrabovský, M; Huege, T; Hussain, M; Iarlori, M; Insolia, A; Ionita, F; Italiano, A; Jiraskova, S; Kaducak, M; Kampert, K H; Karova, T; Kasper, P; Kégl, B; Keilhauer, B; Kemp, E; Kieckhafer, R M; Klages, H O; Kleifges, M; Kleinfeller, J; Knapik, R; Knapp, J; Koang, D -H; Krieger, A; Krömer, O; Kruppke-Hansen, D; Kühn, F; Kuempel, D; Kulbartz, K; Kunka, N; Kusenko, A; LaRosa, G; Lachaud, C; Lago, B L; Lautridou, P; Leão, M S A B; Lebrun, D; Lebrun, P; Lee, J; de Oliveira, M A Leigui; Lemiere, A; Letessier-Selvon, A A; Leuthold, M; Lhenry-Yvon, I; López, R; Agüera, A Lopez; Louedec, K; Bahilo, J Lozano; Lucero, A; Lyberis, H; Maccarone, M C; Macolino, C; Maldera, S; Mandat, D; Mantsch, P; Mariazzi, A G; Maris, I C; Falcon, H R Marquez; Martello, D; Bravo, O Martínez; Mathes, H J; Matthews, J; Matthews, J A J; Matthiae, G; Maurizio, D; Mazur, P O; McEwen, M; McNeil, R R; Medina-Tanco, G; Melissas, M; Melo, D; Menichetti, E; Menshikov, A; Meyhandan, R; Micheletti, M I; Miele, G; Miller, W; Miramonti, L; Mollerach, S; Monasor, M; Ragaigne, D Monnier; Montanet, F; Morales, B; Morello, C; Moreno, J C; Morris, C; Mostafá, M; Moura, C A; Müller, S; Muller, M A; Mussa, R; Navarra, G; Navarro, J L; Navas, S; Necesal, P; Nellen, L; Newman-Holmes, C; Newton, D; Nhung, P T; Nierstenhoefer, N; Nitz, D; Nosek, D; Nožka, L; Nyklicek, M; Oehlschläger, J; Olinto, A; Oliva, P; Olmos-Gilbaja, V M; Ortiz, M; Pacheco, N; Selmi-Dei, D Pakk; Palatka, M; Pallotta, J; Parente, G; Parizot, E; Parlati, S; Pastor, S; Patel, M; Paul, T; Pavlidou, V; Payet, K; Pech, M; Pȩkala, J; Pepe, I M; Perrone, L; Pesce, R; Petermann, E; Petrera, S; Petrinca, P; Petrolini, A; Petrov, Y; Petrovic, J; Pfendner, C; Piegaia, R; Pierog, T; Pimenta, M; Pinto, T; Pirronello, V; Pisanti, O; Platino, M; Pochon, J; Ponce, V H; Pontz, M; Privitera, P; Prouza, M; Quel, E J; Rautenberg, J; Ravel, O; Ravignani, D; Redondo, A; Revenu, B; Rezende, F A S; Rídky, J; Riggi, S; Risse, M; Rivière, C; Rizi, V; Robledo, C; Rodríguez, G; Martino, J Rodriguez; Rojo, J Rodriguez; Rodriguez-Cabo, I; Rodríguez-Frías, M D; Ros, G; Rosado, J; Rossler, T; Roth, M; Rouillé-d'Orfeuil, B; Roulet, E; Rovero, A C; Salamida, F; Salazar, H; Salina, G; Sánchez, F; Santander, M; Santo, C E; Santos, E M; Sarazin, F; Sarkar, S; Sato, R; Scharf, N; Scherini, V; Schieler, H; Schiffer, P; Schmidt, A; Schmidt, F; Schmidt, T; Scholten, O; Schoorlemmer, H; Schovancova, J; Schovánek, P; Schroeder, F; Schulte, S; Schüssler, F; Schuster, D; Sciutto, S J; Scuderi, M; Segreto, A; Semikoz, D; Settimo, M; Shellard, R C; Sidelnik, I; Siffert, B B; Sigl, G; Śmiałkowski, A; Šmída, R; Smith, B E; Snow, G R; Sommers, P; Sorokin, J; Spinka, H; Squartini, R; Strazzeri, E; Stutz, A; Suárez, F; Suomijärvi, T; Supanitsky, A D; Sutherland, M S; Swain, J; Szadkowski, Z; Tamashiro, A; Tamburro, A; Tarutina, T; Taşcuau, O; Tcaciuc, R; Tcherniakhovski, D; Tegolo, D; Thao, N T; Thomas, D; Ticona, R; Tiffenberg, J; Timmermans, C; Tkaczyk, W; Peixoto, C J Todero; Tomé, B; Tonachini, A; Torres, I; Travnicek, P; Tridapalli, D B; Tristram, G; Trovato, E; Tueros, M; Ulrich, R; Unger, M; Urban, M; Galicia, J F Valdés; Valiño, I; Valore, L; vandenBerg, A M; Vázquez, J R; Vázquez, R A; Veberič, D; Velarde, A; Venters, T; Verzi, V; Videla, M; Villaseñor, L; Vorobiov, S; Voyvodic, L; Wahlberg, H; Wahrlich, P; Wainberg, O; Warner, D; Watson, A A; Westerhoff, S; Whelan, B J; Wieczorek, G; Wiencke, L; Wilczyńska, B; Wilczyński, H; Wileman, C; Winnick, M G; Wu, H; Wundheiler, B; Yamamoto, T; Younk, P; Yuan, G; Yushkov, A; Zas, E; Zavrtanik, D; Zavrtanik, M; Zaw, I; Zepeda, A; Ziolkowski, M

    2009-01-01

    Reports on the atmospheric monitoring, calibration, and other operating systems of the Pierre Auger Observatory. Contributions to the 31st International Cosmic Ray Conference, Lodz, Poland, July 2009.

  14. Heat treatment effect on the electronic and magnetic structures of nanographene sheets investigated through electron spectroscopy and conductance measurements.

    Science.gov (United States)

    Takashiro, Jun-ichi; Kudo, Yasuhiko; Kaneko, Satoshi; Takai, Kazuyuki; Ishii, Takafumi; Kyotani, Takashi; Enoki, Toshiaki; Kiguchi, Manabu

    2014-04-28

    The heat treatment effect on the electronic and magnetic structures of a disordered network of nanographene sheets has been investigated by in situ measurements of X-ray photoemission spectroscopy, near-edge X-ray absorption fine structure (NEXAFS), and electrical conductance, together with temperature-programmed desorption measurements. Oxygen-containing functional groups bonded to nanographene edges in the pristine sample are almost completely decomposed under heat treatment up to 1300-1500 K, resulting in the formation of edges primarily terminated by hydrogen. The removal of the oxygen-containing groups enhances the conductance owing to the decrease in the electron transport barriers between nanographene sheets. Heat treatment above 1500 K removes also the hydrogen atoms from the edges, promoting the successive fusion of nanographene sheets at the expense of edges. The decrease in the π* peak width in NEXAFS indicates the progress of the fusion reaction, that is, the extension of the π-conjugation, which agrees with the increase in the orbital susceptibility previously reported. The fusion leads to the formation of local π/sp(2) bridges between nanographene sheets and brings about an insulator-to-metal transition at 1500-1600 K, at which the bridge network becomes infinite. As for the magnetism, the intensity of the edge state peak in NEXAFS, which corresponds to the number of the spin-polarized edge states, decreases above 1500 K, though the effective edge-state spin density per edge state starts decreasing at approximately 200 K lower than the temperature of the edge state peak change. This disagreement indicates the development of antiferromagnetic short range ordering as a precursor of a spin glass state near the insulator-metal transition, at which the random network of inter-nanographene-sheet exchange interactions strengthened with the formation of the π/sp(2) bridges becomes infinite. PMID:24618730

  15. The fate of free radicals in a cellulose based hydrogel: detection by electron paramagnetic resonance spectroscopy.

    Science.gov (United States)

    Basumallick, Lipika; Ji, J Andrea; Naber, Nariman; Wang, Y John

    2009-07-01

    Cellulose derivatives are commonly used as gelling agents in topical and ophthalmic drug formulations. During the course of manufacturing, cellulose derivatives are believed to generate free radicals. These free radicals may degrade the gelling agent, leading to lower viscosity. Free radicals also may react with the active ingredient in the product. The formation of radicals in a 3% hydrogel of hypromellose (hydroxypropyl methylcellulose) was monitored by electron paramagnetic resonance (EPR) spectroscopy and spin trapping techniques. Radicals were trapped with 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) and quantitated by comparing the EPR intensity with 4-hydroxy-2,2,6,6-tetramethylpiperidinyloxy (TEMPOL), a stable free radical. Typically, the hydrogels showed an initial increase in the radical concentration within 2 days after autoclaving, followed by a drop in radical concentration in 7 days. EDTA prevented the formation of free radicals in the hypromellose (HPMC) hydrogel, suggesting the involvement of metal ions in the generation of free radicals. The oxidizing potential of the hydrogel was estimated by measuring the rate at which methionine (a model for the protein active pharmaceutical ingredient) was degraded, and was consistent with the amount of radicals present in the gel. This study is the first report investigating the application of EPR spectroscopy in detecting and estimating free radical concentration in cellulose based hydrogels. PMID:19090570

  16. 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.

  17. 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.

  18. CHARACTERIZATION OF REFINED HEMP FIBERS USING NIR FT RAMAN MICRO SPECTROSCOPY AND ENVIRONMENTAL SCANNING ELECTRON MICROSCOPY

    Directory of Open Access Journals (Sweden)

    Siva Kumar Kovur

    2008-11-01

    Full Text Available The research was focused on the separation of single hemp (Cannabis sativa L. fibre cells with low fineness from mechanically extracted fibre bundles of high fineness. The fiber bundles were treated with enzymes, namely panzym, pectinase, hemicellulase, and cellulase, along with a combination of panzym and ultrasonic treatments. Changes in the fiber structure were followed at molecular and microscopic levels by means of NIR FT Raman spectroscopy and Environmental Scanning Electron Microscopy (ESEM. Buffer-panzym treatments of hemp fibers had a prominent effect in loosening of the fiber cells. The best of refining was achieved when the fiber bundles were treated with buffer-panzym solution in combination with ultrasonic treatment.

  19. White light scattering spectroscopy and electron microscopy of laser induced melting in single gold nanorods.

    Science.gov (United States)

    Zijlstra, Peter; Chon, James W M; Gu, Min

    2009-07-28

    We present the first measurements of laser induced melting and reshaping of single gold nanorods. Using a combination of white light scattering spectroscopy and electron microscopy we find a melting energy of 260 fJ for nanorods with an average size of 92 x 30 nm. Contrary to previous reports on ensembles of nanorods, this melting energy corresponds well to the theoretical prediction of 225 fJ. We observe a gradual shape change from a long and thin rod to a shorter and wider rod, which eventually collapses into a sphere when enough laser energy is deposited. We also observe that higher aspect ratio particles are thermodynamically less stable, leading to a greater reduction of the aspect ratio at lower laser pulse energy densities.

  20. Valence orbitals of W(CO)6 using electron momentum spectroscopy

    Institute of Scientific and Technical Information of China (English)

    Shi Le-Lei; Liu Kun; Luo Zhi-Hong; Ning Chuan-Gang; Deng Jing-Kang

    2011-01-01

    The binding energy spectra and the momentum distributions of the outer valence orbitals of W(CO)6 have been studied by using electron momentum spectroscopy as well as non-relativistic,scalar relativistic and spin-orbital relativistic DFT-B3LYP calculations.The experimental momentum profiles of the outer valence orbitals obtained with the impact energies of 1200 eV and 2400 eV were compared with various theoretical calculation results.The relativistic calculations could provide better descriptions for the experimental momentum distributions than the non-relativistic ones.Moreover,a new ordering of orbitals 10t1u,3t2g,and 7eg,i.e.,10t1u < 3t2g <7eg <10a1g,is established in this work.

  1. Strong Asymmetric Charge Carrier Dependence in Inelastic Electron Tunneling Spectroscopy of Graphene Phonons.

    Science.gov (United States)

    Natterer, Fabian D; Zhao, Yue; Wyrick, Jonathan; Chan, Yang-Hao; Ruan, Wen-Ying; Chou, Mei-Yin; Watanabe, Kenji; Taniguchi, Takashi; Zhitenev, Nikolai B; Stroscio, Joseph A

    2015-06-19

    The observation of phonons in graphene by inelastic electron tunneling spectroscopy has been met with limited success in previous measurements arising from weak signals and other spectral features which inhibit a clear distinction between phonons and miscellaneous excitations. Utilizing a back-gated graphene device that allows adjusting the global charge carrier density, we introduce an averaging method where individual tunneling spectra at varying charge carrier density are combined into one representative spectrum. This method improves the signal for inelastic transitions while it suppresses dispersive spectral features. We thereby map the total graphene phonon density of states, in good agreement with density functional calculations. Unexpectedly, an abrupt change in the phonon intensity is observed when the graphene charge carrier type is switched through a variation of the back-gate electrode potential. This sudden variation in phonon intensity is asymmetric in the carrier type, depending on the sign of the tunneling bias.

  2. Nanostructured lipid carriers as nitroxide depot system measured by electron paramagnetic resonance spectroscopy.

    Science.gov (United States)

    Haag, S F; Chen, M; Peters, D; Keck, C M; Taskoparan, B; Fahr, A; Teutloff, C; Bittl, R; Lademann, J; Schäfer-Korting, M; Meinke, M C

    2011-12-15

    Various nanometer scaled transport systems are used in pharmaceutics and cosmetics to increase penetration or storage of actives. Nanostructured lipid carriers (NLCs) are efficient drug delivery systems for dermatological applications. Electron paramagnetic resonance (EPR) spectroscopy was used for the determination of TEMPO (2,2,6,6-tetramethyl-1-piperidinyloxy) distribution within the carrier and to investigate the dynamics of skin penetration. Results of ex vivo penetration of porcine skin and in vivo data - forearm of human volunteers - are compared and discussed to previously obtained results with invasomes under comparable conditions. W-band measurements show 35% of TEMPO associated with the lipid compartments of the NLC. Application of TEMPO loaded NLC to skin ex vivo increases the observation time by 12min showing a stabilisation of the nitroxide radical. Moreover, stabilisation is also seen with data generated in vivo. Thus, same as invasomes NLCs are a suitable slow release depot system. PMID:22001533

  3. Dosimetry of electron and gamma radiation with alanine/ESR spectroscopy

    International Nuclear Information System (INIS)

    A new method for the preparation of alanine dosimeters was investigated. The absorbed dose response of these dosimeters was demonstrated for 10 MeV electron and 60Co gamma radiation in the range from 20 Gy to 1.1 kGy. Concentration of the irradiation-induced free radicals in the alanine was determined by ESR spectroscopy. In addition to measurements at ambient temperature, the alanine dosimeters were also subjected to thermal treatment during irradiation (up to about 50 deg. C) in order to assess their performance characteristics under extreme conditions which might arise in future technical applications. The results show that under normal conditions the alanine calibration curves are linear, whereas at higher temperatures the dosimeters require a correction of 0.3%/K for absorbed doses above 200 Gy. (author)

  4. Reaction of C2HCl2+O2: Combined TR-FTIR Spectroscopy and Electronic Structure

    Science.gov (United States)

    Xiang, Tian-Cheng; Wang, Huan; Liu, Kun-hui; Zhao, Hong-mei; Wu, Wei-qiang; Su, Hong-mei

    2009-12-01

    The product channels and mechanisms of the C2HCl2+O2 reaction are investigated by step-scan time-resolved Fourier transform infrared emission spectroscopy and the G3MP2//B3LYP/6-311G(d,p) level of electronic structure calculations. Vibrationally excited products of HCl, CO, and CO2 are observed in the IR emission spectra and the product vibrational state distribution are determined which shows that HCl and CO are vibrationally excited with the nascent average vibrational energy estimated to be 59.8 and 51.8 kJ/mol respectively. In combination with the G3MP2//B3LYP/6-311G(d,p) calculations, the reaction mechanisms have been characterized and the energetically favorable reaction pathways have been suggested.

  5. Investigation into two-component phosphate glasses by X-ray electron spectroscopy

    International Nuclear Information System (INIS)

    Using the method of X-ray electron spectroscopy double glass-like and certain crystal phosphates containing mono and bivalent cations are investigated. The identity of spectra of frame levels and valents band of glass-like and crystal analogues points to the preservation of the near order in glasses. Using the method, bridge and non-bridge oxygen atoms (P-O-R and P=O) can be discriminated in glass-like and crystal phosphates containing mono- and bivalent cations, but it is quite impossible to distinguish the bonds P-O-R and P=O. The chemical shift 01 s in bicomponent phosphate glasses increases with an increase in the modifier content. In the case of alkali-earth ions the chemical shift 01s is determined by the sequene Be→Mg→Ca→Sr→Ba. The chemical shift P2p increases with an increase in the number of non-bridge oxygen atoms

  6. Nuclear spectroscopy and electron microprobe study of a Ba hot particle originating from the Chernobyl accident

    Energy Technology Data Exchange (ETDEWEB)

    Vapirev, E.I.; Bourin, K.I.; Hristova, A.V.; Gourev, V. (Sofia Univ. (Bulgaria). Fizicheski Fakultet); Tsacheva, Ts. (Bulgarian Academy of Sciences, Sofia (Bulgaria). Inst. of Physical Chemistry); Kamenova, Ts. (Bylgarska Akademiya na Naukite, Sofia (Bulgaria). Inst. po Metaloznanie i Tekhnologiya na Metalite)

    1994-01-01

    A Ba-Sr hot particle released during the Chernobyl accident has been studied by electron microprobe analysis and alpha, beta and gamma spectroscopy. The Ba-Sr hot particle proved in terms of mass to be a Zr hot particle. It has been concluded that the Zr has a nuclear origin through the chain Br-Kr-Rb-Sr-Y-Zr. The estimated specific activity is approximately 1.8 [+-] 0.5 Bq.[mu]m[sup -3] which is comparable to the estimated activity of [approx] 1 Bq.[mu]m[sup -3] of the UO[sub 2] hot particles. The conclusions with reference to the risk when such a particle is inhaled is that the risk of a Ba-Sr-Zr hot particle is not greater than the risk due to standard UO[sub 2] hot particles. (author).

  7. Electronic structure investigation of atomic layer deposition ruthenium(oxide) thin films using photoemission spectroscopy

    Science.gov (United States)

    Schaefer, Michael; Schlaf, Rudy

    2015-08-01

    Analyzing and manipulating the electronic band line-up of interfaces in novel micro- and nanoelectronic devices is important to achieve further advancement in this field. Such band alignment modifications can be achieved by introducing thin conformal interfacial dipole layers. Atomic layer deposition (ALD), enabling angstrom-precise control over thin film thickness, is an ideal technique for this challenge. Ruthenium (Ru0) and its oxide (RuO2) have gained interest in the past decade as interfacial dipole layers because of their favorable properties like metal-equivalent work functions, conductivity, etc. In this study, initial results of the electronic structure investigation of ALD Ru0 and RuO2 films via photoemission spectroscopy are presented. These experiments give insight into the band alignment, growth behavior, surface structure termination, and dipole formation. The experiments were performed in an integrated vacuum system attached to a home-built, stop-flow type ALD reactor without exposing the samples to the ambient in between deposition and analysis. Bis(ethylcyclopentadienyl)ruthenium(II) was used as precursor and oxygen as reactant. The analysis chamber was outfitted with X-ray photoemission spectroscopy (LIXPS, XPS). The determined growth modes are consistent with a strong growth inhibition situation with a maximum average growth rate of 0.21 Å/cycle for RuO2 and 0.04 Å/cycle for Ru.0 An interface dipole of up to -0.93 eV was observed, supporting the assumption of a strongly physisorbed interface. A separate experiment where the surface of a RuO film was sputtered suggests that the surface is terminated by an intermediate, stable, non-stoichiometric RuO2/OH compound whose surface is saturated with hydroxyl groups.

  8. Electronic structure investigation of atomic layer deposition ruthenium(oxide) thin films using photoemission spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Schaefer, Michael, E-mail: mvschaefer@mail.usf.edu, E-mail: schlaf@mail.usf.edu [Department of Physics, University of South Florida, Tampa, Florida 33620 (United States); Schlaf, Rudy, E-mail: mvschaefer@mail.usf.edu, E-mail: schlaf@mail.usf.edu [Department of Electrical Engineering, University of South Florida, Tampa, Florida 33620 (United States)

    2015-08-14

    Analyzing and manipulating the electronic band line-up of interfaces in novel micro- and nanoelectronic devices is important to achieve further advancement in this field. Such band alignment modifications can be achieved by introducing thin conformal interfacial dipole layers. Atomic layer deposition (ALD), enabling angstrom-precise control over thin film thickness, is an ideal technique for this challenge. Ruthenium (Ru{sup 0}) and its oxide (RuO{sub 2}) have gained interest in the past decade as interfacial dipole layers because of their favorable properties like metal-equivalent work functions, conductivity, etc. In this study, initial results of the electronic structure investigation of ALD Ru{sup 0} and RuO{sub 2} films via photoemission spectroscopy are presented. These experiments give insight into the band alignment, growth behavior, surface structure termination, and dipole formation. The experiments were performed in an integrated vacuum system attached to a home-built, stop-flow type ALD reactor without exposing the samples to the ambient in between deposition and analysis. Bis(ethylcyclopentadienyl)ruthenium(II) was used as precursor and oxygen as reactant. The analysis chamber was outfitted with X-ray photoemission spectroscopy (LIXPS, XPS). The determined growth modes are consistent with a strong growth inhibition situation with a maximum average growth rate of 0.21 Å/cycle for RuO{sub 2} and 0.04 Å/cycle for Ru.{sup 0} An interface dipole of up to −0.93 eV was observed, supporting the assumption of a strongly physisorbed interface. A separate experiment where the surface of a RuO film was sputtered suggests that the surface is terminated by an intermediate, stable, non-stoichiometric RuO{sub 2}/OH compound whose surface is saturated with hydroxyl groups.

  9. Direct band gap measurement of Cu(In,Ga)(Se,S){sub 2} thin films using high-resolution reflection electron energy loss spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Heo, Sung [Analytical Engineering Group, Samsung Advanced Institute of Technology, 130 Samsung-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do 443-803 (Korea, Republic of); College of Information and Communication Engineering, Sungkyunkwan University, Cheoncheon-dong 300, Jangan-gu, Suwon 440-746 (Korea, Republic of); Lee, Hyung-Ik; Park, Jong-Bong; Ko, Dong-Su; Chung, JaeGwan; Kim, KiHong; Kim, Seong Heon; Yun, Dong-Jin; Ham, YongNam; Park, Gyeong Su [Analytical Engineering Group, Samsung Advanced Institute of Technology, 130 Samsung-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do 443-803 (Korea, Republic of); Song, Taewon [Energy lab, Samsung Advanced Institute of Technology, 130 Samsung-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do 443-803 (Korea, Republic of); Lee, Dongho, E-mail: dhlee0333@gmail.com; Nam, Junggyu [PV Development Team, Energy Solution Business Division, Samsung SDI, 467 Beonyeong-ro, Cheonan-si, Chungcheongnam-do 331-330 (Korea, Republic of); Kang, Hee Jae [Department of Physics, Chungbuk National University, Gaesin-dong, Heungdeok-gu, Cheongju, 361-763 (Korea, Republic of); Choi, Pyung-Ho; Choi, Byoung-Deog, E-mail: bdchoi@skku.edu [College of Information and Communication Engineering, Sungkyunkwan University, Cheoncheon-dong 300, Jangan-gu, Suwon 440-746 (Korea, Republic of)

    2015-06-29

    To investigate the band gap profile of Cu(In{sub 1−x},Ga{sub x})(Se{sub 1−y}S{sub y}){sub 2} of various compositions, we measured the band gap profile directly as a function of in-depth using high-resolution reflection energy loss spectroscopy (HR-REELS), which was compared with the band gap profile calculated based on the auger depth profile. The band gap profile is a double-graded band gap as a function of in-depth. The calculated band gap obtained from the auger depth profile seems to be larger than that by HR-REELS. Calculated band gaps are to measure the average band gap of the spatially different varying compositions with respect to considering its void fraction. But, the results obtained using HR-REELS are to be affected by the low band gap (i.e., out of void) rather than large one (i.e., near void). Our findings suggest an analytical method to directly determine the band gap profile as function of in-depth.

  10. Terahertz time-domain spectroscopy of two-dimensional electron gasses at high magnetic fields

    Science.gov (United States)

    Curtis, Jeremy A.

    This dissertation covers two projects that were in the logical path to studying decoherence in a high mobility GaAs two--dimensional electron gas at high magnetic fields. The first project is the ultrafast non--degenerate pump--probe spectroscopic study of bulk GaAs in the Split Florida Helix at the National High Magnetic Field Laboratory at Florida State University. This project was undertaken as a proof of concept that ultrafast optics could be done in the Split Florida Helix so that we might study a high mobility two dimensional electron gas using THz time--domain spectroscopy at high magnetic fields, which is a much more complicated measurement than the pump--probe discussed here. This demonstration was a success. We completed the first ultrafast optical study of any kind in the Florida Split Helix. We collected differential reflection data from this bulk sample that exhibited electronic and oscillatory components. These components were treated independently in the analysis by treating the electronic dynamics with a four level approximation. The electronic transition rates were extracted and agreed well with published values. This agreement is a demonstration that the spectrometer functioned as desired. The oscillatory response was found to be a result of the emission of coherent phonons upon electronic transition between the four levels. The frequency of the oscillatory response was extracted and agreed well with the theoretical value. The second project is the study of the temperature dependence of the cyclotron decay lifetimes in a Landau quantized GaAs high mobility two dimensional electron gas using THz time--domain spectroscopy at relatively low magnetic field (1.25 T). We find that the cyclotron decay lifetimes decrease monotonically with increasing temperature from 0.4 K to 100 K and that the primary pulse amplitudes increase from 0.4 K to 1.2 K, saturates above 1.2 K up to 50 K, and decreases rapidly above 50 K. We attribute this rapid drop in

  11. Experimental and theoretical study of 3p photoionization and subsequent Auger decay in atomic chromium

    Science.gov (United States)

    Keskinen, J.; Huttula, S.-M.; Mäkinen, A.; Patanen, M.; Huttula, M.

    2015-12-01

    3p photoionization and subsequent low kinetic energy Coster-Kronig and super Coster-Kronig Auger decay have been studied in atomic chromium. The binding energies, line widths, and relative intensities for the transitions seen in the synchrotron radiation excited 3p photoelectron spectrum are determined. The high resolution M2,3 M4,5 M4,5 and M2,3 M4,5 N1 Auger electron spectra following the electron impact excited 3p ionization are presented and the kinetic energies, relative intensities, and identifications are given for the main lines. The experimental findings are compared with the theoretical predictions obtained from Hartree-Fock and multiconfiguration Dirac-Fock approaches.

  12. Electronic Properties of Hydrogen Storage Materials with Photon-in/Photon-out Soft-X-Ray Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Jinghua

    2008-09-22

    The applications of resonant soft X-ray emission spectroscopy on a variety of carbon systems have yielded characteristic fingerprints. With high-resolution monochromatized synchrotron radiation excitation, resonant inelastic X-ray scattering has emerged as a new source of information about electronic structure and excitation dynamics. Photon-in/photon-out soft-X-ray spectroscopy is used to study the electronic properties of fundamental materials, nanostructure, and complex hydrides and will offer potential in-depth understanding of chemisorption and/or physisorption mechanisms of hydrogen adsorption/desorption capacity and kinetics.

  13. 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...

  14. Theoretical study of core-loss electron energy-loss spectroscopy at graphene nanoribbon edges

    Science.gov (United States)

    Fujita, N.; Hasnip, P. J.; Probert, M. I. J.; Yuan, J.

    2015-08-01

    A systematic study of simulated atomic-resolution electronic energy-loss spectroscopy (EELS) for different graphene nanoribbons (GNRs) is presented. The results of ab initio studies of carbon 1s core-loss EELS on GNRs with different ribbon edge structures and different hydrogen terminations show that theoretical core-loss EELS can distinguish key structural features at the atomic scale. In addition, the combination of polarized core-loss EELS with symmetry resolved electronic partial density of states calculations can be used to identify the origins of all the primary features in the spectra. For example, the nature of the GNR edge structure (armchair, zigzag, etc) can be identified, along with the degree of hydrogenation. Hence it is possible to use the combination of ab initio calculations with high resolution, high energy transmission core-loss EELS experiments to determine the local atomic arrangement and chemical bonding states (i.e. a structural fingerprint) in GNRs, which is essential for future practical applications of graphene.

  15. Nanoscale Concentration Quantification of Pharmaceutical Actives in Amorphous Polymer Matrices by Electron Energy-Loss Spectroscopy.

    Science.gov (United States)

    Ricarte, Ralm G; Lodge, Timothy P; Hillmyer, Marc A

    2016-07-26

    We demonstrated the use of electron energy-loss spectroscopy (EELS) to evaluate the composition of phenytoin:hydroxypropyl methylcellulose acetate succinate (HPMCAS) spin-coated solid dispersions (SDs). To overcome the inability of bright-field and high-angle annular dark-field TEM imaging to distinguish between glassy drug and polymer, we used the π-π* transition peak in the EELS spectrum to detect phenytoin within the HPMCAS matrix of the SD. The concentration of phenytoin within SDs of 10, 25, and 50 wt % drug loading was quantified by a multiple least-squares analysis. Evaluating the concentration of 50 different regions in each SD, we determined that phenytoin and HPMCAS are intimately mixed at a length scale of 200 nm, even for drug loadings up to 50 wt %. At length scales below 100 nm, the variance of the measured phenytoin concentration increases; we speculate that this increase is due to statistical fluctuations in local concentration and chemical changes induced by electron irradiation. We also performed EELS analysis of an annealed 25 wt % phenytoin SD and showed that the technique can resolve concentration differences between regions that are less than 50 nm apart. Our findings indicate that EELS is a useful tool for quantifying, with high accuracy and sub-100 nm spatial resolution, the composition of many pharmaceutical and soft matter systems. PMID:27419264

  16. Tetrachloridocuprates(II)—Synthesis and Electron Paramagnetic Resonance (EPR) Spectroscopy

    Science.gov (United States)

    Winter, Alette; Zabel, André; Strauch, Peter

    2012-01-01

    Ionic liquids (ILs) on the basis of metal containing anions and/or cations are of interest for a variety of technical applications e.g., synthesis of particles, magnetic or thermochromic materials. We present the synthesis and the results of electron paramagnetic resonance (EPR) spectroscopic analyses of a series of some new potential ionic liquids based on tetrachloridocuprates(II), [CuCl4]2−, with different sterically demanding cations: hexadecyltrimethylammonium 1, tetradecyltrimethylammonium 2, tetrabutylammonium 3 and benzyltriethylammonium 4. The cations in the new compounds were used to achieve a reasonable separation of the paramagnetic Cu(II) ions for EPR spectroscopy. The EPR hyperfine structure was not resolved. This is due to the exchange broadening, resulting from still incomplete separation of the paramagnetic Cu(II) centers. Nevertheless, the principal values of the electron Zeemann tensor (g║ and g┴) of the complexes could be determined. Even though the solid substances show slightly different colors, the UV/Vis spectra are nearly identical, indicating structural changes of the tetrachloridocuprate moieties between solid state and solution. The complexes have a promising potential e.g., as high temperature ionic liquids, as precursors for the formation of copper chloride particles or as catalytic paramagnetic ionic liquids. PMID:22408411

  17. Revisiting the inelastic electron tunneling spectroscopy of single hydrogen atom adsorbed on the Cu(100) surface.

    Science.gov (United States)

    Jiang, Zhuoling; Wang, Hao; Sanvito, Stefano; Hou, Shimin

    2015-12-21

    Inelastic electron tunneling spectroscopy (IETS) of a single hydrogen atom on the Cu(100) surface in a scanning tunneling microscopy (STM) configuration has been investigated by employing the non-equilibrium Green's function formalism combined with density functional theory. The electron-vibration interaction is treated at the level of lowest order expansion. Our calculations show that the single peak observed in the previous STM-IETS experiments is dominated by the perpendicular mode of the adsorbed H atom, while the parallel one only makes a negligible contribution even when the STM tip is laterally displaced from the top position of the H atom. This propensity of the IETS is deeply rooted in the symmetry of the vibrational modes and the characteristics of the conduction channel of the Cu-H-Cu tunneling junction, which is mainly composed of the 4s and 4pz atomic orbitals of the Cu apex atom and the 1s orbital of the adsorbed H atom. These findings are helpful for deepening our understanding of the propensity rules for IETS and promoting IETS as a more popular spectroscopic tool for molecular devices.

  18. Inelastic electron tunnelling and noise spectroscopies in organic magnetic tunnel junctions with PTCDA barrier

    Science.gov (United States)

    Aliev, Farkhad; Martinez, Isidoro; Hong, Jhen-Yong; Cascales, Juan Pedro; Andres, Pablo; Lin, Minn-Tsong

    2015-03-01

    The influence of internal barrier dynamics on spin, charge transport and their fluctuations in organic spintronics remains poorly understood. Here we present inelastic electron tunnelling spectroscopy (IETS) and low frequency noise (LFN) studies in magnetic tunnel junctions with thin (1.2-5nm) organic PTCDA barriers in the tunnelling regime at temperatures down to 0.3K. Shot noise is superpoissonian with a Fano factor exceeding in 1.5-2 times the maximum values reported for magnetic tunnel junctions with inorganic barriers, indicating spin dependent bunching in tunneling. IETS results show energy relaxation of tunneling electrons through the excitation of collective (librons) and internal (phonons) vibrational modes of the molecules. The bias dependence of the normalised 1/f noise studied up to 350mV reveals that the excitation of some phonon modes has a strong impact on LFN with over a 10-fold reproducible increase near some specific biases. The dependence of the IETS and LFN anomalies with the relative magnetic alignment of the electrodes will also be discussed.

  19. Theoretical study of core-loss electron energy-loss spectroscopy at graphene nanoribbon edges.

    Science.gov (United States)

    Fujita, N; Hasnip, P J; Probert, M I J; Yuan, J

    2015-08-01

    A systematic study of simulated atomic-resolution electronic energy-loss spectroscopy (EELS) for different graphene nanoribbons (GNRs) is presented. The results of ab initio studies of carbon [Formula: see text] core-loss EELS on GNRs with different ribbon edge structures and different hydrogen terminations show that theoretical core-loss EELS can distinguish key structural features at the atomic scale. In addition, the combination of polarized core-loss EELS with symmetry resolved electronic partial density of states calculations can be used to identify the origins of all the primary features in the spectra. For example, the nature of the GNR edge structure (armchair, zigzag, etc) can be identified, along with the degree of hydrogenation. Hence it is possible to use the combination of ab initio calculations with high resolution, high energy transmission core-loss EELS experiments to determine the local atomic arrangement and chemical bonding states (i.e. a structural fingerprint) in GNRs, which is essential for future practical applications of graphene.

  20. Molecular potentials and wave function mapping by high-resolution electron spectroscopy and ab initio calculations

    Energy Technology Data Exchange (ETDEWEB)

    Kimberg, Victor, E-mail: victor.kimberg@pks.mpi.de [Max Planck Institute for the Physics of Complex Systems, Nöthnitzer Straße 38, 01187 Dresden (Germany); Miron, Catalin, E-mail: miron@synchrotron-soleil.fr [Synchrotron SOLEIL, l’Orme des Merisiers, Saint-Aubin, BP 48, FR-91192 Gif-sur-Yvette Cedex (France)

    2014-08-15

    Highlights: • Some studies related to the vibrational wave functions mapping phenomenon are reviewed. • The core-excited vibrational wave functions were mapped using dissociative and bound final states. • High-resolution experimental data is accompanied by ab initio calculations. • The mapping phenomenon allows one to extract constants of the molecular potentials. • The mapping techniques are general and can be applied for the study of many systems. - Abstract: The recent development of high brightness 3{sup rd} generation soft X-ray sources and high energy resolution electron spectrometers made it possible to accurately trace quantum phenomena associated to the vibrational dynamics in core-excited molecules. The present paper reviews the recent results on mapping of vibrational wave functions and molecular potentials based on electron spectroscopy. We discuss and compare the mapping phenomena in various systems, stressing the advantages of the resonant X-ray scattering for studying of the nuclear dynamics and spectroscopic constants of small molecules. The experimental results discussed in the paper are most often accompanied by state-of-the-art ab initio calculations allowing for a deeper understanding of the quantum effects. Besides its fundamental interest, the vibrational wave function mapping is shown to be useful for the analysis of core- and valence-excited molecular states based on the reflection principle.

  1. Revisiting the inelastic electron tunneling spectroscopy of single hydrogen atom adsorbed on the Cu(100) surface

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Zhuoling; Wang, Hao [Centre for Nanoscale Science and Technology, Key Laboratory for the Physics and Chemistry of Nanodevices, Department of Electronics, Peking University, Beijing 100871 (China); Sanvito, Stefano [School of Physics, AMBER and CRANN Institute, Trinity College, Dublin 2 (Ireland); Hou, Shimin, E-mail: smhou@pku.edu.cn [Centre for Nanoscale Science and Technology, Key Laboratory for the Physics and Chemistry of Nanodevices, Department of Electronics, Peking University, Beijing 100871 (China); Beida Information Research (BIR), Tianjin 300457 (China)

    2015-12-21

    Inelastic electron tunneling spectroscopy (IETS) of a single hydrogen atom on the Cu(100) surface in a scanning tunneling microscopy (STM) configuration has been investigated by employing the non-equilibrium Green’s function formalism combined with density functional theory. The electron-vibration interaction is treated at the level of lowest order expansion. Our calculations show that the single peak observed in the previous STM-IETS experiments is dominated by the perpendicular mode of the adsorbed H atom, while the parallel one only makes a negligible contribution even when the STM tip is laterally displaced from the top position of the H atom. This propensity of the IETS is deeply rooted in the symmetry of the vibrational modes and the characteristics of the conduction channel of the Cu-H-Cu tunneling junction, which is mainly composed of the 4s and 4p{sub z} atomic orbitals of the Cu apex atom and the 1s orbital of the adsorbed H atom. These findings are helpful for deepening our understanding of the propensity rules for IETS and promoting IETS as a more popular spectroscopic tool for molecular devices.

  2. 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.

  3. Data Processing at the Pierre Auger Observatory

    CERN Document Server

    Vicha, J

    2015-01-01

    Cosmic-ray particles with ultra-high energies (above $10^{18}$ eV) are studied through the properties of extensive air showers which they initiate in the atmosphere. The Pierre Auger Observatory detects these showers with unprecedented exposure and precision and the collected data are processed via dedicated software codes. Monte Carlo simulations of extensive air showers are very computationally expensive, especially at the highest energies and calculations are performed on the GRID for this purpose. The processing of measured and simulated data is described, together with a brief list of physics results which have been achieved.

  4. Recent Results from the Pierre Auger observatory

    International Nuclear Information System (INIS)

    The Pierre Auger observatory is a hybrid air shower experiment which uses multiple detection techniques to investigate the origin, spectrum, and composition of ultrahigh energy cosmic rays. We present recent results on these topics and discuss their implications to the understanding the origin of the most energetic particles in nature as well as for physics beyond the Standard Model, such as violation of Lorentz invariance and 'top-down' models of cosmic ray production. Future plans, including enhancements underway at the southern site in Argentina will be presented. (author)

  5. Absolute calibration of the Auger fluorescence detectors

    Energy Technology Data Exchange (ETDEWEB)

    Bauleo, P.; Brack, J.; Garrard, L.; Harton, J.; Knapik, R.; Meyhandan, R.; Rovero, A.C.; /Buenos Aires, IAFE; Tamashiro, A.; Warner, D.

    2005-07-01

    Absolute calibration of the Pierre Auger Observatory fluorescence detectors uses a light source at the telescope aperture. The technique accounts for the combined effects of all detector components in a single measurement. The calibrated 2.5 m diameter light source fills the aperture, providing uniform illumination to each pixel. The known flux from the light source and the response of the acquisition system give the required calibration for each pixel. In the lab, light source uniformity is studied using CCD images and the intensity is measured relative to NIST-calibrated photodiodes. Overall uncertainties are presently 12%, and are dominated by systematics.

  6. 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.

  7. 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.

  8. Modification of valence-band symmetry and Auger threshold energy in biaxially compressed InAs1-xSbx

    International Nuclear Information System (INIS)

    Strained-layer superlattices (SLS's) with biaxially compressed InAs1-xSbx were characterized using magnetophotoluminescence and compared with unstrained InAs1-xSbx alloys. Holes in the SLS exhibited a decrease in effective mass, approaching that of the electrons. In the two-dimensional limit, a large increase in the Auger threshold energy accompanies this strain-induced change in SLS valence-band symmetry. Correspondingly, the activation energy for nonradiative recombination in the SLS's displayed a marked increase compared with that of the unstrained alloys. Strained-layer superlattices and alloy activation energies are in agreement with estimated Auger threshold energies

  9. Determination of the Antioxidant Status of the Skin by In Vivo-Electron Paramagnetic Resonance (EPR) Spectroscopy

    OpenAIRE

    Silke Barbara Lohan; Anna-Christina Lauer; Sophia Arndt; Annette Friedrich; Kathrin Tscherch; Stefan F. Haag; Darvin, Maxim E.; Henning Vollert; Anke Kleemann; Ingo Gersonde; Norbert Groth; Jürgen Lademann; Sascha Rohn; Martina Claudia Meinke

    2015-01-01

    Organisms produce free radicals which are essential for various metabolic processes (enzymatic oxidation, cellular respiration, signaling). Antioxidants are important chemical compounds that specifically prevent the oxidation of substances by scavenging radicals, especially reactive oxygen species (ROS). Made up of one or two unpaired electrons, ROS are free radicals that are highly reactive and can attack other metabolites. By using electron paramagnetic resonance (EPR) spectroscopy, it is p...

  10. Energies and radiative and Auger rates of doubly-excited states of multiply charged Be-like ions

    Institute of Scientific and Technical Information of China (English)

    苟秉聪; 陈信义

    1995-01-01

    The energy levels, radiative and Auger rates of Be-iike ions are calculated using the conventional configuration-interaction method. The Be-like ions are different from He-like ions because the excited electrons in the former deviate from O(4) symmetry.

  11. Depth resolution at profile Auger analysis of the ZnS-PbxSn1-xTe structures

    International Nuclear Information System (INIS)

    The reasons have been studied of anomalously large broadening of profiles at the interface at profile Auger-analysis of the structures ZnS-PbxSn1-xTe, grown by a moleclar-beam epitaxy method. It is shown that this broadening is not related with the existance of the extended region of a valiable composition. Other possible mechanisms of profile persistance have been studied experimentally. In place of the analysis an effectively greater rate of ion etching is observed. It is found that the Auger-profile shape near the interface is determined by the surface relief formation at ion etching. It is shown that the reason of the formation of a developed relief of the surface in the place periodically irradiated by the electron beam during obtaining the Auger-spectra has an electrostatic character. Two possible mechanisms of such relies formation are discussed

  12. Education and public outreach of the Pierre Auger Observatory

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, B.; /Natl. Tech. U., San Rafael; Snow, G.

    2005-08-01

    The Auger collaboration's broad mission in education, outreach and public relations is coordinated in a separate task. Its goals are to encourage and support a wide range of outreach efforts that link schools and the public with the Auger scientists and the science of cosmic rays, particle physics, and associated technologies. This report focuses on recent activities and future initiatives.

  13. Emission Spectroscopy as a Probe into Photoinduced Intramolecular Electron Transfer in Polyazine Bridged Ru(II,Rh(III Supramolecular Complexes

    Directory of Open Access Journals (Sweden)

    Karen J. Brewer

    2010-08-01

    Full Text Available Steady-state and time-resolved emission spectroscopy are valuable tools to probe photochemical processes of metal-ligand, coordination complexes. Ru(II polyazine light absorbers are efficient light harvesters absorbing in the UV and visible with emissive 3MLCT excited states known to undergo excited state energy and electron transfer. Changes in emission intensity, energy or band-shape, as well as excited state lifetime, provide insight into excited state dynamics. Photophysical processes such as intramolecular electron transfer between electron donor and electron acceptor sub-units may be investigated using these methods. This review investigates the use of steady-state and time-resolved emission spectroscopy to measure excited state intramolecular electron transfer in polyazine bridged Ru(II,Rh(III supramolecular complexes. Intramolecular electron transfer in these systems provides for conversion of the emissive 3MLCT (metal-to-ligand charge transfer excited state to a non-emissive, but potentially photoreactive, 3MMCT (metal-to-metal charge transfer excited state. The details of the photophysics of Ru(II,Rh(III and Ru(II,Rh(III,Ru(II systems as probed by steady-state and time-resolved emission spectroscopy will be highlighted.

  14. Development of time-resolved (e, 2e) electron momentum spectroscopy: a tool for visualizing the motion of electrons during a chemical reaction

    International Nuclear Information System (INIS)

    We report the instrumental design and technical details of an (e, 2e) electron momentum spectroscopy (EMS) apparatus, which employs an ultrashort-pulsed incident electron beam with a repetition rate of 5 kHz and a pulse duration in the order of one picosecond. EMS data for the neutral Ar atom in the ground state measured by using the pulsed electron beam are presented to illustrate the potential abilities of the apparatus for ultrafast molecular dynamics. The results are discussed mainly in terms of signal intensity

  15. Electronic structure of aromatic amino acids studied by soft x-ray spectroscopy

    Science.gov (United States)

    Zhang, Wenhua; Carravetta, Vincenzo; Plekan, Oksana; Feyer, Vitaliy; Richter, Robert; Coreno, Marcello; Prince, Kevin C.

    2009-07-01

    The electronic structure of phenylalanine, tyrosine, tryptophan, and 3-methylindole in the gas phase was investigated by x-ray photoemission spectroscopy (XPS) and near edge x-ray absorption fine structure (NEXAFS) spectroscopy at the C, N, and O K-edges. The XPS spectra have been calculated for the four principal conformers of each amino acid, and the spectra weighted by the Boltzmann population ratios calculated from published free energies. Instead of the single peaks expected from the stoichiometry of the compounds, the N 1s core level spectra of phenylalanine and tryptophan show features indicating that more than one conformer is present. The calculations reproduce the experimental features. The C and O 1s spectra do not show evident effects due to conformational isomerism. The calculations predict that such effects are small for carbon, and for oxygen it appears that only broadening occurs. The carbon K-edge NEXAFS spectra of these aromatic amino acids are similar to the published data of the corresponding molecules in the solid state, but show more structure due to the higher resolution in the present study. The N K-edge spectra of tryptophan and 3-methylindole differ from phenylalanine and tyrosine, as the first two both contain a nitrogen atom located in a pyrrole ring. The nitrogen K-edge NEXAFS spectra of aromatic amino acids do not show any measurable effects due to conformational isomerism, in contrast to the photoemission results. Calculations support this result and show that variations of the vertical excitation energies of different conformers are small, and cannot be resolved in the present experiment. The O NEXAFS spectra of these three aromatic compounds are very similar to other, simpler amino acids, which have been studied previously.

  16. 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

  17. 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.

  18. Potential-induced electronic structure changes in supercapacitor electrodes observed by in operando soft X-ray spectroscopy.

    Science.gov (United States)

    Bagge-Hansen, Michael; Wood, Brandon C; Ogitsu, Tadashi; Willey, Trevor M; Tran, Ich C; Wittstock, Arne; Biener, Monika M; Merrill, Matthew D; Worsley, Marcus A; Otani, Minoru; Chuang, Cheng-Hao; Prendergast, David; Guo, Jinghua; Baumann, Theodore F; van Buuren, Tony; Biener, Jürgen; Lee, Jonathan R I

    2015-03-01

    The dynamic physiochemical response of a functioning graphene-based aerogel supercapacitor is monitored in operando by soft X-ray spectroscopy and interpreted through ab initio atomistic simulations. Unanticipated changes in the electronic structure of the electrode as a function of applied voltage bias indicate structural modifications across multiple length scales via independent pseudocapacitive and electric double layer charge storage channels. PMID:25503328

  19. Broadband 2D Electronic Spectroscopy Reveals Coupling Between Dark 1Bu- State of Carotenoid and Qx State of Bacteriochlorophyll

    Directory of Open Access Journals (Sweden)

    Scholes Gregory D.

    2013-03-01

    Full Text Available The study of LH2 protein of purple bacteria by broadband 2D electronic spectroscopy is presented. The dark 1Bu- carotenoid state is directly observed in 2D spectra and its role in carotenoid-bacteriochlorophyll interaction is discussed.

  20. 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 g