WorldWideScience

Sample records for emission-auger electron spectroscopy

  1. Electron spectroscopy

    International Nuclear Information System (INIS)

    Hegde, M.S.

    1979-01-01

    An introduction to the various techniques in electron spectroscopy is presented. These techniques include: (1) UV Photoelectron spectroscopy, (2) X-ray Photoelectron spectroscopy, (3) Auger electron spectroscopy, (4) Electron energy loss spectroscopy, (5) Penning ionization spectroscopy and (6) Ion neutralization spectroscopy. The radiations used in each technique, the basis of the technique and the special information obtained in structure determination in atoms and molecules by each technique are summarised. (A.K.)

  2. Electron Paramagnetic Resonance Spectroscopy

    Indian Academy of Sciences (India)

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

  3. Auger electron spectroscopy

    International Nuclear Information System (INIS)

    Gopalaraman, C.P.

    1975-01-01

    General features of electron excited Auger electron spectroscopy (AES) which is a nondestructive technique for the analysis of surfaces upto about 15 Adeg depth with a detection limit of about 0.1% of a monolayer. Methods of measuring the Auger electron energies and recent improvements in the instrumentation are reviewed. Typical energy resolution is found to be about 0.5% which is specially suited for the detection of light elements. It is widely used in metallurgy, surface chemistry and thin film studies. (K.B.)

  4. Auger electron spectroscopy, ionization loss spectroscopy, appearance potential spectroscopy

    International Nuclear Information System (INIS)

    Riwan, R.

    1973-01-01

    The spectroscopy of surfaces using an incident electron beam is studied. The fundamental mechanisms are discussed together with the parameters involved in Auger emission: excitation of the atom, de-excitation by electron emission, and the migration of electrons towards the surface and their ejection. Some examples of applications are given (surface structures, metallurgy, chemical information). Two new techniques for analyzing surfaces are studied: ionization spectroscopy, and appearance potential spectroscopy [fr

  5. Molecular studies by electron spectroscopy

    International Nuclear Information System (INIS)

    Hansteen, J.M.

    1977-01-01

    Experience gained in experimental nuclear physics has played a large role in the development of electron spectroscopy as a powerful tool for studying chemical systems. The use of ESCA (Electron Spectroscopy for Chemical Analysis) for the mapping of molecular properties connected with inner as well as outer electron shells is reviewed, mainly from a phenomological point of view. Molecular Auger electron spectroscopy is described as a means of gaining information on details in molecular structure, simultaneously being extensively applied for surface studies. Future highly promising research areas for molecular electron spectroscopy are suggested to be (e,2e) processes as well as continued exploitation of synchrotron radiation from high energy nuclear devices. (Auth.)

  6. ESR spectroscopy and electron distribution

    International Nuclear Information System (INIS)

    Davies, A.G.

    1997-01-01

    EPR spectroscopy can map out the electron distribution in a molecule, in much the same way as proton NMR spectroscopy can map out the proton distribution, and it provides some of the most direct evidence for the principal concepts underlying the electronic theory of organic structure and mechanism. This is illustrated for phenomena of conjugation, hyper-conjugation, substituent effects in annulenes, Hueckel theory, ring strain, the Mills-Nixon effect, and ion pairing. (author)

  7. electron energy-loss spectroscopy

    International Nuclear Information System (INIS)

    Egerton, R.

    1997-01-01

    As part of a commemorative series of articles to mark the hundredth anniversary of the discovery of the electron, this article describes the use of electron energy-loss spectroscopy. The physical and chemical properties of materials can be studied by considering the energy that electrons use as they travel through a solid, often in conjunction with other analytical techniques. The technique is often combined with electron diffraction and high-resolution imaging and can be used to provide elemental identification down to the atomic scale. 6 figs

  8. Electron energy-loss spectroscopy

    International Nuclear Information System (INIS)

    Egerton, R.

    1997-01-01

    As part of the commemorative series of articles to mark the hundredth anniversary of the discovery of the electron, this article discusses electron energy-loss spectroscopy. The physical and chemical properties of materials can be studied by considering the energy that electrons use as they travel through a solid, often in conjunction with other analytical techniques. The technique is often combined with electron diffraction and high-resolution imaging and can be used to provide elemental identification down to the atomic scale. (UK)

  9. 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...

  10. Electron momentum spectroscopy

    International Nuclear Information System (INIS)

    McCarthy, I.E.

    1986-03-01

    For electron energies greater than a few hundred eV and recoil momenta less than a few atomic units, the differential cross section for the non-coplanar symmetric (e,2e) reaction on an atom or molecule depends on the target and ion structure only through the target-ion overlap. Experimental criteria for the energy and momentum are that the apparent structure information does not change when the energy and momentum are varied. The plane-wave impulse approximation is a sufficient description of the reaction mechanism for determining spherically-averaged squares of momentum-space orbitals for atoms and molecules and for coefficients describing initial and final state correlations

  11. Principles of electron tunneling spectroscopy

    CERN Document Server

    Wolf, E L

    2012-01-01

    Electron tunnelling spectroscopy as a research tool has strongly advanced understanding of superconductivity. This book explains the physics and instrumentation behind the advances illustrated in beautiful images of atoms, rings of atoms and exotic states in high temperature superconductors, and summarizes the state of knowledge that has resulted.

  12. Auger electron spectroscopy of alloys

    International Nuclear Information System (INIS)

    Kuijers, F.J.

    1978-01-01

    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.)

  13. PAC spectroscopy of electronic ceramics

    International Nuclear Information System (INIS)

    Gardner, J.A.; Wang, R.; Schwenker, R.; Sommers, J.A.

    1991-01-01

    Dilute indium dopants in cerium oxides and YBa 2 Cu 3 O x have been studied by 111 In/Cd Perturbed Angular Correlation (PAC) spectroscopy. By controlling oxygen vacancy concentration in the cerium oxides through doping or high-temperature vacuum annealing, we have found that indium always forms a defect complex unless the sample is doped to reduce greatly the oxygen vacancy concentration. Three different vacancy-associated complexes are found with concentrations that depend on doping and oxygen stoichiometry. Another defect complex occurs in samples having negligible vacancy concentration. At low temperatures, evidence is found of interaction with an electronic hole trapped by 111 Cd after the radioactive decay of the 111 In parent. In YBa 2 Cu 3 O x the indium substitutes preferentially at the Y site but has measurable probability of substitution in at least one of the two copper sites. A symmetry change near 650 C is consistent with the well-documented orthorhombic/tetragonal transition for samples in air or oxygen. (author). 23 refs, 10 figs

  14. Vibrational spectroscopy in the electron microscope.

    Science.gov (United States)

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

    2014-10-09

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

  15. Inner-shell electron spectroscopy for microanalysis

    International Nuclear Information System (INIS)

    Joy, D.C.; Maher, D.M.

    1979-01-01

    The transmission electron energy-loss spectrum shows characteristic edges corresponding to the excitation of inner-shell electrons of atoms in a thin sample. Analysis of these edges provides detailed chemical, structural, and electronic data from the radiated volume. By combining electron spectroscopy and electron microscopy, this microanalytical technique can be performed in conjunction with high-resolution imaging of the sample. It is shown that this approach has advantages of sensitivity, spatial resolution, and convenience over other comparable techniques. 7 figures

  16. Electron attachment cross sections obtained from electron attachment spectroscopy

    International Nuclear Information System (INIS)

    Popp, P.; Baumbach, J.I.; Leonhardt, J.W.; Mothes, S.

    1988-01-01

    Electron capture detectors have a high sensitivity for substances with high thermal electron attachment cross sections. The electron attachment spectroscopy makes it possible to change the mean electron energy in such a way that the maximum for dissociative electron attachment is reached. Thus, best operation modes of the detection system as well as significant dependencies of electron attachment coefficients are available. Cross sections for electron attachment as a function of the electron energy are obtained with the knowledge of electron energy distribution functions from Boltzmann equation analysis by a special computer code. A disadvantage of this electron attachment spectroscopy is the superposition of space charge effects due to the decrease of the electron drift velocity with increasing mean electron energy. These influences are discussed. (author)

  17. 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.

  18. Electron-electron coincidence spectroscopies at surfaces

    International Nuclear Information System (INIS)

    Stefani, G.; Iacobucci, S.; Ruocco, A.; Gotter, R.

    2002-01-01

    In the past 20 years, a steadily increasing number of electron-electron coincidence experiments on atoms and molecules have contributed to a deeper understanding of electron-electron correlation effects. In more recent years this technique has been extended to the study of solid surfaces. This class of one photon IN two electrons OUT experiments will be discussed with an emphasis on grazing incidence geometry, that is expected to be particularly suited for studying surfaces. The crucial question of which is the dominant mechanism that leads to ejection of pairs of electron from the surface will be addressed. It will be shown that, depending on the kinematics chosen, the correlated behaviour of the pairs of electrons detected might be singled out from independent particle one

  19. Narrow electron injector for ballistic electron spectroscopy

    International Nuclear Information System (INIS)

    Kast, M.; Pacher, C.; Strasser, G.; Gornik, E.

    2001-01-01

    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 ΔE inj =10 meV is derived. [copyright] 2001 American Institute of Physics

  20. Conversion electron spectroscopy in transfermium nuclei

    International Nuclear Information System (INIS)

    Herzberg, R.D.

    2003-01-01

    Conversion electron spectroscopy is an essential tool for the spectroscopy of heavy deformed nuclei. The conversion electron spectrometer SACRED has been used in conjunction with the gas-filled recoil separator RITU to study conversion electron cascades in 254 No. The spectra reveal the ground state rotational bands down to low spin. A detailed analysis of the background seen for 254 No shows that approximately 40% of the decay path goes via excited high K bands which may be built on an isomer. (orig.)

  1. Depth sectioning using electron energy loss spectroscopy

    International Nuclear Information System (INIS)

    D'Alfonso, A J; Findlay, S D; Allen, L J; Cosgriff, E C; Kirkland, A I; Nellist, P D; Oxley, M P

    2008-01-01

    The continued development of electron probe aberration correctors for scanning transmission electron microscopy has enabled finer electron probes, allowing atomic resolution column-by-column electron energy loss spectroscopy. Finer electron probes have also led to a decrease in the probe depth of focus, facilitating optical slicing or depth sectioning of samples. The inclusion of post specimen aberration corrected image forming lenses allows for scanning confocal electron microscopy with further improved depth resolution and selectivity. We show that in both scanning transmission electron microscopy and scanning confocal electron microscopy geometries, by performing a three dimensional raster scan through a specimen and detecting electrons scattered with a characteristic energy loss, it will be possible to determine the location of isolated impurities embedded within the bulk.

  2. Electron capture and energy-gain spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Taulbjerg, K.

    1989-01-01

    The applicability of translation energy spectroscopy as a tool to determine individual reaction cross sections in atomic collisions is analyzed with special emphasis on the electron capture process in highly charged ion collisions. A condition is derived to separate between higher collision energies where translation energy spectroscopy is problem free and lower energies where strong overlap of individual spectra features prohibits an analysis of the total translation energy spectrum by means of a simple deconvolution procedure. 8 refs., 6 figs.

  3. Penning ionization processes studied by electron spectroscopy

    International Nuclear Information System (INIS)

    Yencha, A.J.

    1978-01-01

    The technique of measuring the kinetic energy of electrons ejected from atomic or molecular species as a result of collisional energy transfer between a metastable excited rare gas atom and an atom or molecule is known as Penning ionization spectroscopy. Like the analogous photoionization process of photoelectron spectroscopy, a considerable amount of information has been gained about the ionization potentials of numerous molecular systems. It is, in fact, through the combined analyses of photoelectron and Penning electron spectra that affords a probe of the particle-particle interactions that occur in the Penning process. In this paper a short survey of the phenomenon of Penning ionization, as studied by electron spectroscopy, will be presented as it pertains to the ionization processes of simple molecules by metastable excited atoms. (author)

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

    International Nuclear Information System (INIS)

    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 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

  5. 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.

  6. Dynamical effects in electron spectroscopy

    International Nuclear Information System (INIS)

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

    2015-01-01

    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

  7. Spectroscopy of two-electron atoms

    International Nuclear Information System (INIS)

    Desesquelles, J.

    1988-01-01

    Spectroscopy of heliumlike ions is discussed putting emphasis on mid and high Z atoms. Experimental aspects of ion charge, excitation production, clean spectra, and precise wavelength measurement are detailed. Recent results obtained at several laboratories including Lyon, Argonne, Notre-Dame, Oxford, Berkeley, Darmstadt, Paris, are used to test the QED contributions and higher order relativistic corrections to two-electron atom energies. (orig.)

  8. Single Molecule Spectroscopy of Electron Transfer

    International Nuclear Information System (INIS)

    Holman, Michael; Zang, Ling; Liu, Ruchuan; Adams, David M.

    2009-01-01

    The objectives of this research are threefold: (1) to develop methods for the study electron transfer processes at the single molecule level, (2) to develop a series of modifiable and structurally well defined molecular and nanoparticle systems suitable for detailed single molecule/particle and bulk spectroscopic investigation, (3) to relate experiment to theory in order to elucidate the dependence of electron transfer processes on molecular and electronic structure, coupling and reorganization energies. We have begun the systematic development of single molecule spectroscopy (SMS) of electron transfer and summaries of recent studies are shown. There is a tremendous need for experiments designed to probe the discrete electronic and molecular dynamic fluctuations of single molecules near electrodes and at nanoparticle surfaces. Single molecule spectroscopy (SMS) has emerged as a powerful method to measure properties of individual molecules which would normally be obscured in ensemble-averaged measurement. Fluctuations in the fluorescence time trajectories contain detailed molecular level statistical and dynamical information of the system. The full distribution of a molecular property is revealed in the stochastic fluctuations, giving information about the range of possible behaviors that lead to the ensemble average. In the case of electron transfer, this level of understanding is particularly important to the field of molecular and nanoscale electronics: from a device-design standpoint, understanding and controlling this picture of the overall range of possible behaviors will likely prove to be as important as designing ia the ideal behavior of any given molecule.

  9. Two-dimensional vibrational-electronic spectroscopy

    Science.gov (United States)

    Courtney, Trevor L.; Fox, Zachary W.; Slenkamp, Karla M.; Khalil, Munira

    2015-10-01

    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 (νCN) and either a ligand-to-metal charge transfer transition ([FeIII(CN)6]3- dissolved in formamide) or a metal-to-metal charge transfer (MMCT) transition ([(CN)5FeIICNRuIII(NH3)5]- 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 νCN 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 wide range of complex molecular, material, and biological systems.

  10. 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

  11. Auger electron spectroscopy of alloy surfaces

    International Nuclear Information System (INIS)

    Overbury, S.H.; Somorjai, G.A.

    1975-03-01

    Regular solution models are used to predict surface segregation of the constituent of lowest surface free energy in homogeneous multicomponent systems. Analysis of the Auger electron emission intensities from alloys yield the surface composition and the depth distribution of the composition near the surface. Auger Electron Spectroscopy (AES) studies of the surface composition of the Ag--Au and Pb--In systems have been carried out as a function of bulk composition and temperature. Although these alloys have very different regular solution parameters their surface compositions are predictable by the regular solution models. (U.S.)

  12. 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...

  13. Electron spectroscopy with fast heavy ions

    International Nuclear Information System (INIS)

    Schneider, D.

    1983-01-01

    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

  14. Implementation of the Electron conversion Moessbauer spectroscopy

    International Nuclear Information System (INIS)

    Hernandez, Torres, D.; Noriega Scull, C.

    1996-01-01

    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

  15. A computer simulation of auger electron spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Ragheb, M S; Bakr, M H.S. [Dept. Of Accellerators and Ion Sources, Division of Basic Nuclear Sciences, NRC, Atomic Energy Authority, (Egypt)

    1997-12-31

    A simulation study of Auger electron spectroscopy was performed to reveal how far the dependency between the different parameters governing the experimental behavior affects the peaks. The experimental procedure followed by the AC modulation technique were reproduced by means of a computer program. It generates the assumed output Auger electron peaks, exposes them to a retarding AC modulated field and collects the resulting modulated signals. The program produces the lock-in treatment in order to demodulate the signals revealing the Auger peaks. It analyzes the spectrum obtained giving the peak positions and energies. Comparison between results of simulation and the experimental data showed good agreement. The peaks of the spectrum obtained depend upon the amplitude, frequency and resolution of the applied modulated signal. The peak shape is effected by the rise time, the slope and the starting potential of the retarding field. 4 figs.

  16. Application of principal component and factor analyses in electron spectroscopy

    International Nuclear Information System (INIS)

    Siuda, R.; Balcerowska, G.

    1998-01-01

    Fundamentals of two methods, taken from multivariate analysis and known as principal component analysis (PCA) and factor analysis (FA), are presented. Both methods are well known in chemometrics. Since 1979, when application of the methods to electron spectroscopy was reported for the first time, they became to be more and more popular in different branches of electron spectroscopy. The paper presents examples of standard applications of the method of Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS), and electron energy loss spectroscopy (EELS). Advantages one can take from application of the methods, their potentialities as well as their limitations are pointed out. (author)

  17. FTIR spectroscopy of electron irradiated polymers

    International Nuclear Information System (INIS)

    Finch, D.S.

    1988-04-01

    The chemical changes in electron beam irradiated polymers, in particular PVC, are considered in order to relate the formation of conjugated structures to changes in the electrical properties. Infrared spectroscopy has been used to measure these changes. Fourier Transform techniques and computing facilities make better data processing possible. A method for base line interpretation is demonstrated whereby a shift parallel to the abscisal axis in a region of the polymer that is non absorbing is used to evaluate the baseline. This technique has proved to be highly reproducible providing that the polymer films to be examined are optically homogeneous. Evaluation of the rate of decay of the total area of the carbon chlorine region of the polymer has been compared with the chlorine decay curve analysed by the measurement of x-ray emission during irradiation of bulk samples. The significant reduction in the evolution of atomic chlorine through x-ray analysis has been attributed to the trapping of HCl within the polymer film and its subsequent slow diffusion out of the polymer. With PVC, one of the main products as a result of irradiation is the formation of conjugated sequences. These were studied by the use of uv-visible spectroscopy. (author)

  18. Hot Electron Nanoscopy and Spectroscopy (HENs)

    KAUST Repository

    Giugni, Andrea; Torre, Bruno; Allione, Marco; Perozziello, Gerardo; Candeloro, Patrizio; Di Fabrizio, Enzo M.

    2017-01-01

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

  19. Hot Electron Nanoscopy and Spectroscopy (HENs)

    KAUST Repository

    Giugni, Andrea

    2017-08-17

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

  20. Auger electron spectroscopy studies of boron carbide

    International Nuclear Information System (INIS)

    Madden, H.H.; Nelson, G.C.; Wallace, W.O.

    1986-01-01

    Auger electron spectroscopy has been used to probe the electronic structure of ion bombardment (IB) cleaned surfaces of B 9 C and B 4 C samples. The shapes of the B-KVV and C-KVV Auger lines were found to be relatively insensitive to the bulk stoichiometry of the samples. This indicates that the local chemical environments surrounding B and C atoms, respectively, on the surfaces of the IB cleaned samples do not change appreciably in going from B 9 C to B 4 C. Fracturing the sample in situ is a way of producing a clean representative internal surface to compare with the IB surfaces. Microbeam techniques have been used to study a fracture surface of the B 9 C material with greater spatial resolution than in our studies of IB surfaces. The B 9 C fracture surface was not homogeneous and contained both C-rich and B-rich regions. The C-KVV line for the C-rich regions was graphitic in shape. Much of the C-rich regions was found by IB to be less than 100 nm in thickness. The C-KVV line from the B-rich regions was carbidic and did not differ appreciably in shape from those recorded for the IB cleaned surfaces

  1. Chemical information from Auger electron spectroscopy

    International Nuclear Information System (INIS)

    Madden, H.H.

    1981-01-01

    The nature of chemical information in Auger electron spectroscopy (AES) data is reviewed with special emphasis on data from solid surface systems. Two strategies are most frequently used to extract this information: (i) measuring and analyzing energy (chemical) shifts in Auger peaks; and (ii) making use of the shapes of Auger signals to determine the chemical environment at the site of the initial core hole. Chemical shift data are primarily illustrated by highlighting the interaction of oxygen with solids; and analyses of these data based on core-level binding-energy shifts, relaxation, and hole--hole interactions are outlined and discussed. Auger transitions that involve valence electrons are usually those for which lineshapes are taken as indications of the local chemistry at the initial core-hole site. Attempts at extracting valence band density-of-states information from lineshapes are proving successful and this approach to the surface chemical information in AES is illustrated with the aid of examples dealing with the interaction of silicon with hydrogen and with oxygen. The use of the AES lineshapes simply as ''fingerprints'' of the core-hole-site chemistry is examined and illustrated by examples which include studies of silicon nitride properties, of solid surface properties related to catalytic reactions, and of passive films on iron. Auger decay activated desorption processes are briefly examined and found to promise new and unique chemical information when combined with conventional AES. Some gas phase AES studies are also briefly reviewed

  2. Center Line Slope Analysis in Two-Dimensional Electronic Spectroscopy

    OpenAIRE

    ?anda, Franti?ek; Perl?k, V?clav; Lincoln, Craig N.; Hauer, J?rgen

    2015-01-01

    Center line slope (CLS) analysis in 2D infrared spectroscopy has been extensively used to extract frequency?frequency correlation functions of vibrational transitions. We apply this concept to 2D electronic spectroscopy, where CLS is a measure of electronic gap fluctuations. The two domains, infrared and electronic, possess differences: In the infrared, the frequency fluctuations are classical, often slow and Gaussian. In contrast, electronic spectra are subject to fast spectral diffusion and...

  3. Electronic resonances in broadband stimulated Raman spectroscopy

    Science.gov (United States)

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

    2016-01-01

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

  4. Electron beam effects in auger electron spectroscopy and scanning electron microscopy

    International Nuclear Information System (INIS)

    Fontaine, J.M.; Duraud, J.P.; Le Gressus, C.

    1979-01-01

    Electron beam effects on Si(100) and 5% Fe/Cr alloy samples have been studied by measurements of the secondary electron yield delta, determination of the surface composition by Auger electron spectroscopy and imaging with scanning electron microscopy. Variations of delta as a function of the accelerating voltage Esub(p) (0.5 -9 Torr has no effect on technological samples covered with their reaction layers; the sensitivities to the beam depend rather on the earlier mechanical, thermal and chemical treatment of the surfaces. (author)

  5. Electron-probe microanalysis: x-ray spectroscopy

    International Nuclear Information System (INIS)

    1987-01-01

    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 [fr

  6. Two-dimensional electronic femtosecond stimulated Raman spectroscopy

    Directory of Open Access Journals (Sweden)

    Ogilvie J.P.

    2013-03-01

    Full Text Available We report two-dimensional electronic spectroscopy with a femtosecond stimulated Raman scattering probe. The method reveals correlations between excitation energy and excited state vibrational structure following photoexcitation. We demonstrate the method in rhodamine 6G.

  7. Electron spectroscopy on high-temperature superconductors and related compounds

    International Nuclear Information System (INIS)

    Knupfer, M.

    1994-01-01

    In the last two classes of materials have been discovered which distinguish themselves due to a transition into the superconducting state at relatively high temperatures. These are the cuprate superconductors and the alkali metal doped fullerenes. In this work the electronic structure of representatives of these materials, undoped and Ca-doped YBa 2 Cu 4 O 8 and A 3 C 60 (A=K, Rb), has been investigated using electron energy-loss spectroscopy and photoemission spectroscopy. (orig.) [de

  8. Spectroscopy of heavy few-electron ions

    International Nuclear Information System (INIS)

    Mokler, P.H.

    1986-07-01

    In this paper we ask first, why is it interesting to investigate heavy-few electron ions. Then the various accelerator-based methods to produce heavy few-electron ions are discussed. In the main part an overview on available heavy few-electron ion data and current experiments is given. The summary will end up with future aspects in this field. (orig.)

  9. Photoelectron spectroscopy via electronic spectroscopy of molecular ions

    International Nuclear Information System (INIS)

    Khan, Z.H.

    1990-01-01

    In this work, a new aspect of the correlation between optical and photoelectron spectra is discussed on the basis of which the first ionization potentials of condensed-ring aromatics can be estimated from certain features in the electronic spectra of their positive ions. Furthermore, it is noticed that the first IP's are very sensitive to molecular size as the latter's inclusion in the regression formulas improves the results considerably. Once the first ionization potential for a molecule is determined, its higher IP's may be computed if the lower-energy electronic bands for its cation are known. This procedure is especially useful for such systems whose uv photoelectron spectra are unknown. (author). 11 refs, 10 figs, 1 tab

  10. Electronic excitation and Auger spectroscopy of hexamethyldissilane

    International Nuclear Information System (INIS)

    Souza, G.G.B. de; Azevedo e Souza, A.C. de; Martins, R.J.; Lucas, C.A.

    1988-01-01

    In this work, it is presented an spectroscopic study of Si 2 (CH 3 ) 6 which presents interesting characteristics in the Si - Si bond. Electron energy loss technique was used in the energy range of 500 - 200 eV for the electron beam. Electronic excitation spectra were obtained for the energy loss range from 5 to 30 eV, and also Auger spectra. (A.C.A.S.) [pt

  11. Electron spectroscopy studies in heavy fermions

    International Nuclear Information System (INIS)

    Arko, A.J.

    1986-02-01

    Photoemission experiments (whereby an electron absorbs a packet of light energy and is able to escape from the host material due to its increased energy) can measure directly the energy distribution of electrons in various materials. Our measurements on a recently-discovered class of metallic materials called ''heavy fermions'' show that the electrons that actually carry the electric current in these metals exist only within an extremely narrow range of energies. This range, which we will call the bandwidth, is narrower than that found in ordinary metals like copper by at least a factor of 10. Indeed it is surprising that they can carry electric current at all since such narrow energy ranges (or band widths) are characteristic of electrons confined to their host atoms, as in a non-metal, rather than of electrons that are free to wander through a metal. 8 refs

  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, such as admi......Impedance spectroscopy is used for the characterization of materials, such as electroceramics, solid and liquid electrochemical cells, dielectrics and also fully integrated devices, such as fuel cells. It consists of measuring the electrical impedance - or a closely related property......, such as admittance or dielectric constant - as a function of frequency and comparing the results with expectations based on physical, chemical, and microstructural models. This article reviews the principles and practical aspects of the technique, the representations of the results, the analysis of data......, 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. Surface analysis by electron spectroscopy. General concepts and applications

    International Nuclear Information System (INIS)

    Feliu, S.

    1993-01-01

    An introduction is made to the techniques of electron spectroscopy (XPS and AES) used in the study of surface phenomena. Their theoretical principles, the singular information supplied by these techniques and their basic instrumentation (vacuum systems, excitation sources and electron analysers) are described. A revision of their applications to the Materials Science and the Corrosion Sciences is also made. Author. 44 refs

  14. A high dutycycle low cost multichannel analyser for electron spectroscopy

    International Nuclear Information System (INIS)

    Norell, K.E.; Baltzer, P.

    1983-03-01

    A high dutycycle multichannel analyzer has been designed and used in time-of-flight electron spectroscopy. The memory capacity is 64k counts. The number of channels is 8192 with a time resolution of 100 ns. An oscilloscope is used to display the spectra synchronous with the counting. The unit has been built with standard electronic components. (author)

  15. Hydrocarbon isotope detection by elastic peak electron spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Kostanovskiy, I.A., E-mail: kostanovskiyia@gmail.com [National Research University MPEI, Krasnokazarmennaya 14, 111250 Moscow (Russian Federation); Afanas’ev, V.P. [National Research University MPEI, Krasnokazarmennaya 14, 111250 Moscow (Russian Federation); Naujoks, D. [Max-Planck-Institut für Plasmaphysik, Teilinstitut Greifswald, Wendelsteinstraße 1, D-17491 Greifswald (Germany); Mayer, M. [Max-Planck-Institut für Plasmaphysik, D-85748 Garching (Germany)

    2015-07-15

    Highlights: • PCVD hydrocarbon coatings containing protium or deuterium are analyzed via NRA, ERD, XPS and EPES. • EPES analysis with modern electron energy analyzer SPECS Phoibos 225 shows a clear signal from the hydrogen isotopes. • Different primary energies and scattering angles help to quantify isotope content from EPES spectra. - Abstract: Experimental results on the hydrocarbon isotope analysis by elastic peak electron spectroscopy are presented. Amorphous hydrocarbon samples (a-C:H, a-C:D) are prepared by PCVD and analyzed by nuclear reaction analysis (NRA), elastic recoil detection analysis (ERD), X-ray photoelectron spectroscopy (XPS) and elastic peak electron spectroscopy (EPES). Electron energy spectra show a clear signal from the hydrogen isotopes deuterium and protium. Different incident energies and scattering geometries help to resolve plasmon and elastic energy losses.

  16. Hydrocarbon isotope detection by elastic peak electron spectroscopy

    International Nuclear Information System (INIS)

    Kostanovskiy, I.A.; Afanas’ev, V.P.; Naujoks, D.; Mayer, M.

    2015-01-01

    Highlights: • PCVD hydrocarbon coatings containing protium or deuterium are analyzed via NRA, ERD, XPS and EPES. • EPES analysis with modern electron energy analyzer SPECS Phoibos 225 shows a clear signal from the hydrogen isotopes. • Different primary energies and scattering angles help to quantify isotope content from EPES spectra. - Abstract: Experimental results on the hydrocarbon isotope analysis by elastic peak electron spectroscopy are presented. Amorphous hydrocarbon samples (a-C:H, a-C:D) are prepared by PCVD and analyzed by nuclear reaction analysis (NRA), elastic recoil detection analysis (ERD), X-ray photoelectron spectroscopy (XPS) and elastic peak electron spectroscopy (EPES). Electron energy spectra show a clear signal from the hydrogen isotopes deuterium and protium. Different incident energies and scattering geometries help to resolve plasmon and elastic energy losses

  17. Spectroscopy of electron irradiated polymers in electron microscope

    International Nuclear Information System (INIS)

    Faraj, S.H.; Salih, S.M.

    1981-01-01

    The damage induced by energetic electrons in the course of irradiation of polymers in a transmission electron microscope was investigated spectroscopically. Damage on the molecular level has been detected at very low exposure doses. These effects have been induced by electron doses less than that received by the specimen when it is situated at its usual place of the specimen stage in the electron microscope by a factor of 1,000. (author)

  18. Electron spectroscopy of nanodiamond surface states

    Energy Technology Data Exchange (ETDEWEB)

    Belobrov, P.I.; Bursill, L.A.; Maslakov, K.I.; Dementjev, A.P

    2003-06-15

    Electronic states of nanodiamond (ND) were investigated by PEELS, XPS and CKVV Auger spectra. Parallel electron energy loss spectra (PEELS) show that the electrons inside of ND particles are sp{sup 3} hybridized but there is a surface layer containing distinct hybridized states. The CKVV Auger spectra imply that the HOMO of the ND surface has a shift of 2.5 eV from natural diamond levels of {sigma}{sub p} up to the Fermi level. Hydrogen (H) treatment of natural diamond surface produces a chemical state indistinguishable from that of ND surfaces using CKVV. The ND electronic structure forms {sigma}{sub s}{sup 1}{sigma}{sub p}{sup 2}{pi}{sup 1} surface states without overlapping of {pi}-levels. Surface electronic states, including surface plasmons, as well as phonon-related electronic states of the ND surface are also interesting and may also be important for field emission mechanisms from the nanostructured diamond surface.

  19. Future directions in electron momentum spectroscopy of matter

    International Nuclear Information System (INIS)

    Weigold, E.

    1998-01-01

    The development of coincidence spectrometers with multivariable detection techniques, higher energy kinematics, monochromated and spin-polarised electron sources, will usher in a new generation of electron momentum spectroscopy revealing new electronic phenomena in atoms, molecules and solids. This will be enhanced by developments in target preparation, such as spin polarised, oriented and aligned atoms and molecules, radicals, surfaces and strongly correlated systems in condensed matter. Copyright (1998) CSIRO Australia

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

    DEFF Research Database (Denmark)

    Baggesen, Jan Conrad; Madsen, Lars Bojer

    2009-01-01

    an analytical model based on an approximate solution to Boltzmann's transport equation to account for the amount and energy distribution of these secondary electrons. Our theory is in good agreement with the electron spectrum found in a recent attosecond streaking experiment. To suppress the background and gain......Attosecond spectroscopy is currently restricted to photon energies around 100 eV. We show that under these conditions, electron-electron scatterings, as the photoelectrons leave the metal, give rise to a tail of secondary electrons with lower energies and hence a significant background. We develop...

  1. Electron impact spectroscopy of methane, silane, and germane

    International Nuclear Information System (INIS)

    Dillon, M.A.; Wang, R.G.; Spence, D.

    1985-01-01

    Electronic spectra of the group IV/sub a/ hydrides, i.e., methane (CH 4 ), silane (SiH 4 ), and germane (GeH 4 ) have been investigated by means of electron energy loss spectroscopy in an energy range that includes all single-electron excitation from the valence shell. Electron impact spectra of the three gases recorded using electrons of 200-eV incidence are presented. The conditions employed were chosen to favor the excitation of states by direct scattering and to exclude those transitions requiring an exchange mechanism

  2. Electron spectroscopy of collisional excited atoms

    International Nuclear Information System (INIS)

    Straten, P. van der.

    1987-01-01

    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

  3. Electron coincidence spectroscopy of sodium and potassium

    International Nuclear Information System (INIS)

    Frost, L.; Weigold, E.

    1982-03-01

    The Na 3s and K 4s electron momentum distributions have been obtained using the noncoplanar symmetric (e,2e) reaction at total energies of 800 eV and 1200 eV. They show excellent agreement with the results of plane wave impulse approximation calculations using Roothaan-Hartree-Fock functions, after small corrections are made for the finite angular resolution of the apparatus. The potassium valence s momentum profile is a little narrower than that for sodium, implying a correspondingly slightly larger spatial distribution of the outer valence electrons. The ratio between the (n-1)p and ns cross-sections at their respective maxima in q-space were measured to be 0.009 +- 0.003 and 0.019 +- 0.003 for Na and K respectively. These cross-section ratios are in agreement with the PWIA calculations

  4. Electronic structure of Pu carbides: photoelectron spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Gouder, T.; Havela, L.; Shick, Alexander; Huber, F.

    2008-01-01

    Roč. 403, č. 5-9 (2008), s. 852-853 ISSN 0921-4526 R&D Projects: GA AV ČR(CZ) IAA100100530 Grant - others:EU(XE) RITA -CT-2006-026176 Institutional research plan: CEZ:AV0Z10100520 Keywords : photoemission * electronic structure * plutonium Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.822, year: 2008

  5. Electron cyclotron emission spectroscopy on thermonuclear plasmas

    International Nuclear Information System (INIS)

    Tubbing, B.J.D.

    1987-01-01

    Analysis of electron cyclotron emission (ECE) enables one to infer the radial profile of the electron temperature in tokamaks. The Dutch FOM institute for plasma physics has designed, built, installed and operated a grating polychromator for ECE measurements at JET. This thesis deals with a few instrumental aspects of this project and with applications of ECE measurements in tokamak physics studies. Ch. 3 and 4 deal with the wave transport in ECE systems. In Ch. 3 a method is developed to infer the mode conversion, which is a source for transmission losses, in a waveguide component from the antenna pattern of its exit aperture. In Ch. 4 the design and manufacture of the waveguide transition system to the grating polychromator are described. In Ch. 5 a method is reported for calibration of the spectrometers, based on the use of a microwave source which simulates a large area blackbody of very high temperature. The feasibility of the method is tested by applying it to two different ECE systems. In Ch. 6 a study of heat pulse propagation in tokamak plasma's, based on measurement of the electron temperature with the grating polychromator, is presented. 105 refs.; 48 figs.; 8 tabs

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

    DEFF Research Database (Denmark)

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

    2006-01-01

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

  7. Energy analyzer for Auger electron spectroscopy and low-energy backscattering ion spectroscopy

    International Nuclear Information System (INIS)

    Volkov, S.S.; Gorelik, V.A.; Gutenko, V.T.; Protopopov, O.D.; Trubitsin, A.A.; Shuvalova, Z.A.; Yakushev, G.A.

    1988-01-01

    Energy analyzer for electron Auger spectroscopy and low-energy backscattering ion spectroscopy is described. Analyzer presents one-cascade variant of cylindrical mirror with second-order focusing. Energy relative resolution is continuously adjusted within 0.2-1.2% limits. Signal/noise relation by Cu Auger-line at 1 muA current of exciting beam changes upper limit of range 150-450

  8. Many-electron effects in photoelectron spectroscopy

    International Nuclear Information System (INIS)

    Martin, R.L.

    1976-06-01

    The deviations from Koopmans' one-electron model of photoionization which lead to satellite structure in the photoelectron spectrum are examined within the formalism of configuration interaction (CI). The mechanisms which contribute to satellite intensity may be classified as continuum state configuration interaction, final ionic state configuration interaction, and initial state configuration interaction. The discussion centers around the last two mechanisms, these being the prime contributors to the satellite intensity well above threshold. Specific examples of theoretical ''spectra'' are presented for the F(1s) region of HF and the 1s region of neon. The agreement between theory and experiment is found to be excellent. In these two instances, initial state configuration interaction contributions increase the satellite intensity and are of nearly equal importance to the final ionic state mixing

  9. Scanning Tunneling Spectroscopy on Electron-Boson Interactions in Superconductors

    OpenAIRE

    Schackert, Michael Peter

    2014-01-01

    This thesis 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Schackert, Michael Peter

    2014-07-01

    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.

  11. 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.

  12. Gamma-ray and electron spectroscopy in nuclear physics

    International Nuclear Information System (INIS)

    Ejiri, H.

    1989-01-01

    This book is devoted to the role of gamma-ray and conversion-electron (γ-e) spectroscopy in developing our understanding of nuclear structure and nuclear reaction-mechanisms. The book was written because of the spectacular development in the last decade of new γ-e spectroscopic methods, and their application to various kinds of nuclear reactions and the need to present γ-e spectroscopy from the point of view of nuclear structure as well as of reaction mechanism. The importance of γ-e spectroscopy is due to the simplicity and familiarity of the electromagnetic interaction, which gives accurate values for many nuclear quantities and reveals special nuclear properties. γ-e spectroscopy is applied to investigate static as well as dynamic nuclear properties over a wide range of excitation energies from the ground state to states of extreme temperatures and angular momentum, including some new degrees of freedom. (author)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-12-15

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

  14. Auger electron and X-ray spectroscopy of hollow atoms

    NARCIS (Netherlands)

    Morgenstern, R; Johnson, RL; Schmidtbocking, H; Sonntag, BF

    1997-01-01

    Hollow atoms as formed during collisions of multiply charged ions on metallic, semiconducting and insulating surfaces have in recent years successfully been investigated by various spectroscopic methods: low- and high-resolution X-ray spectroscopy as well as high resolution Auger electron

  15. 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…

  16. Electronic structure of metallic alloys through Auger and photoemission spectroscopy

    International Nuclear Information System (INIS)

    Kleiman, G.G.; Rogers, J.D.; Sundaram, V.S.

    1981-01-01

    A review is presented of experimental results of electron spectroscopy studies for various series of transition metal alloys as well as a model for their interpretation which leads to the possibility for the first time to determine independently relative variations in the dipole barrier and Fermi energy contributions to the work function. (L.C.) [pt

  17. Electron spectroscopy for atoms, molecules and condensed matter

    International Nuclear Information System (INIS)

    Siegbahn, K.

    1981-12-01

    A review is given of the research performed at the Institute of Physics, Uppsala under the direction of Prof. Siegbahn. in the field of electron spectroscopy applied to solids, liquids and gases. The developemnt of the spectroscopic methods is the central theme of the review. (L.E.)

  18. Secondary electron spectroscopy and Auger microscopy at high spatial resolution. Application to scanning electron microscopy

    International Nuclear Information System (INIS)

    Le Gressus, Claude; Massignon, Daniel; Sopizet, Rene

    1979-01-01

    Secondary electron spectroscopy (SES), Auger electron spectroscopy (AES) and electron energy loss spectroscopy (ELS) are combined with ultra high vacuum scanning microscopy (SEM) for surface analysis at high spatial resolution. Reliability tests for the optical column for the vacuum and for the spectrometer are discussed. Furthermore the sensitivity threshold in AES which is compatible with a non destructive surface analysis at high spatial resolution is evaluated. This combination of all spectroscopies is used in the study of the beam damage correlated with the well known secondary electron image (SEI) darkening still observed in ultra high vacuum. The darkening is explained as a bulk decontamination of the sample rather than as a surface contamination from the residual vacuum gas [fr

  19. Electron momentum spectroscopy of the core state of solid carbon

    International Nuclear Information System (INIS)

    Caprari, R.S.; Clark, S.A.C.; McCarthy, I.E.; Storer, P.J.; Vos, M.; Weigold, E.

    1994-08-01

    Electron momentum spectroscopy (binary encounter (e,2e)) experimental results are presented for the core state of an amorphous carbon allotrope. The (e,2e) cross section has two identifiable regions. One is a narrow energy width 'core band peak' that does not disperse with momentum. At higher binding energies there is an energy diffuse 'multiple scattering continuum', which is a consequence of (e,2e) collisions with core electrons that are accompanied by inelastic scattering of one or more of the incoming or outgoing electrons. Comparisons of experimental momentum distributions with the Hartree-Fock atomic carbon ls orbital are presented for both regions. 16 refs., 4 figs

  20. Electron correlation effects in XUV photoabsorption spectroscopy of atoms

    International Nuclear Information System (INIS)

    Codling, K.

    1976-01-01

    Reference is made to sophisticated experiments involving the measurement of the angular distribution of photo-ejected electrons, coincidence electrons and ion spectroscopy, which can only be interpreted in terms of electron correlation effects. After an introductory review of previous work, the lectures fall under the following headings: experimental procedures (light sources, monochromators, absorption cells, limitations on the simple photoasbsorption experiment, and complementary techniques); experimental results (discrete states in the continuum, gross features in the photoionisation continuum (rare gases, alkalis, alkaline earths, rare earths, transition elements)). (U.K.)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-12-26

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

  2. 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.

  3. Auger electron spectroscopy for the advanced student laboratory

    International Nuclear Information System (INIS)

    Greczylo, Tomasz; Mazur, Piotr; Debowska, Ewa

    2009-01-01

    This paper presents Auger electron spectroscopy with a retarding field analyser designed for an advanced physics experiment carried out in 'Physics Laboratory II' at the Institute of Experimental Physics, University of Wroclaw, Poland. The authors discuss the process of setting up the experiment and the results of the measurement of Auger spectra. The advantages and disadvantages of the apparatus are discussed along with its implementation in the teaching process

  4. Allenylidene Complexes of Ruthenium: Synthesis, Spectroscopy and Electron Transfer Properties

    Czech Academy of Sciences Publication Activity Database

    Winter, R. F.; Záliš, Stanislav

    2004-01-01

    Roč. 248, 15/16 (2004), s. 1565-1583 ISSN 0010-8545 R&D Projects: GA ČR GA203/03/0821; GA MŠk OC D14.20 Institutional research plan: CEZ:AV0Z4040901 Keywords : spectroscopy * allenylidine complexes of ruthenium * electron transfer Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 6.446, year: 2004

  5. Study of solute segregation at interfaces using Auger electron spectroscopy

    International Nuclear Information System (INIS)

    White, C.L.

    1984-01-01

    Interfacial segregation, often confined to within a few atomic distances of the interface, can strongly influence the processing and properties of metals and ceramics. The thinness of such solute-enriched regions can cause them to be particularly suitable for study using surface sensitive microanalytical techniques such as Auger electron spectroscopy (AES). The application of AES to studies of interfacial segregation in metals and ceramics is briefly reviewed, and several examples are presented. 43 references, 14 figures

  6. Electron energy loss spectroscopy of gold nanoparticles on graphene

    International Nuclear Information System (INIS)

    DeJarnette, Drew; Roper, D. Keith

    2014-01-01

    Plasmon excitation decay by absorption, scattering, and hot electron transfer has been distinguished from effects induced by incident photons for gold nanoparticles on graphene monolayer using electron energy loss spectroscopy (EELS). Gold nano-ellipses were evaporated onto lithographed graphene, which was transferred onto a silicon nitride transmission electron microscopy grid. Plasmon decay from lithographed nanoparticles measured with EELS was compared in the absence and presence of the graphene monolayer. Measured decay values compared favorably with estimated radiative and non-radiative contributions to decay in the absence of graphene. Graphene significantly enhanced low-energy plasmon decay, increasing mode width 38%, but did not affect higher energy plasmon or dark mode decay. This decay beyond expected radiative and non-radiative mechanisms was attributed to hot electron transfer, and had quantum efficiency of 20%, consistent with previous reports

  7. DNA Electronic Fingerprints by Local Spectroscopy on Graphene

    Science.gov (United States)

    Balatsky, Alexander

    2013-03-01

    Working and scalable alternatives to the conventional chemical methods of DNA sequencing that are based on electronic/ionic signatures would revolutionize the field of sequencing. The approach of a single molecule imaging and spectroscopy with unprecedented resolution, achieved by Scanning Tunneling Spectroscopy (STS) and nanopore electronics could enable this revolution. We use the data from our group and others in applying this local scanning tunneling microscopy and illustrate possibilities of electronic sequencing of freeze dried deposits on graphene. We will present two types of calculated fingerprints: first in Local Density of States (LDOS) of DNA nucleotide bases (A,C,G,T) deposited on graphene. Significant base-dependent features in the LDOS in an energy range within few eV of the Fermi level were found in our calculations. These features can serve as electronic fingerprints for the identification of individual bases in STS. In the second approach we present calculated base dependent electronic transverse conductance as DNA translocates through the graphene nanopore. Thus we argue that the fingerprints of DNA-graphene hybrid structures may provide an alternative route to DNA sequencing using STS. Work supported by US DOE, NORDITA.

  8. Study of electron beam effects on surfaces using x-ray photoelectron spectroscopy (XPS) and secondary ion mass spectroscopy (SIMS)

    International Nuclear Information System (INIS)

    Gettings, M.; Coad, J.P.

    1976-02-01

    Discrepancies in the surface analyses of oxidised or heavily contaminated materials have been observed between X-ray Photoelectron Spectroscopy (XPS) and techniques using electron beams (primarily Auger Electron Spectroscopy (AES)). These discrepancies can be ascribed to the influence of the primary electron beam and to illustrate the various types of electron effects different materials were analysed using XPS and Secondary Ion Mass Spectroscopy (SIMS) before and after large area electron bombardment. The materials used included chrome and stainless steels, nickel, platinum, glass and brass. (author)

  9. Low-dose electron energy-loss spectroscopy using electron counting direct detectors.

    Science.gov (United States)

    Maigné, Alan; Wolf, Matthias

    2018-03-01

    Since the development of parallel electron energy loss spectroscopy (EELS), charge-coupled devices (CCDs) have been the default detectors for EELS. With the recent development of electron-counting direct-detection cameras, micrographs can be acquired under very low electron doses at significantly improved signal-to-noise ratio. In spectroscopy, in particular in combination with a monochromator, the signal can be extremely weak and the detection limit is principally defined by noise introduced by the detector. Here we report the use of an electron-counting direct-detection camera for EEL spectroscopy. We studied the oxygen K edge of amorphous ice and obtained a signal noise ratio up to 10 times higher than with a conventional CCD.We report the application of electron counting to record time-resolved EEL spectra of a biological protein embedded in amorphous ice, revealing chemical changes observed in situ while exposed by the electron beam. A change in the fine structure of nitrogen K and the carbon K edges were recorded during irradiation. A concentration of 3 at% nitrogen was detected with a total electron dose of only 1.7 e-/Å2, extending the boundaries of EELS signal detection at low electron doses.

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

    International Nuclear Information System (INIS)

    Toutounji, Mohamad

    2013-01-01

    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)

  11. Resonance tunneling electron-vibrational spectroscopy of polyoxometalates.

    Science.gov (United States)

    Dalidchik, F I; Kovalevskii, S A; Balashov, E M

    2017-05-21

    The tunneling spectra of the ordered monolayer films of decamolybdodicobaltate (DMDC) compounds deposited from aqueous solutions on HOPG were measured by scanning tunnel microscopy in air. The DMDC spectra, as well as the tunneling spectra of other polyoxometalates (POMs), exhibit well-defined negative differential resistances (NDRs). The mechanism of formation of these spectral features was established from the collection of revealed NDR dependences on the external varying parameters and found to be common to all systems exhibiting Wannier-Stark localization. A model of biresonance tunneling was developed to provide an explanation for the totality of experimental data, both the literature and original, on the tunneling POM probing. A variant of the tunneling electron-vibrational POM spectroscopy was proposed allowing the determination of the three basic energy parameters-energy gaps between the occupied and unoccupied states, frequencies of the vibrational transitions accompanying biresonance electron-tunneling processes, and electron-vibrational interaction constants on the monomolecular level.

  12. 2012 ELECTRONIC SPECTROSCOPY & DYNAMICS GORDON RESEARCH CONFERENCE, JULY 22-27, 2012

    Energy Technology Data Exchange (ETDEWEB)

    Kohler, Bern

    2012-07-27

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

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

    Directory of Open Access Journals (Sweden)

    Karsten Holldack

    2016-02-01

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

  14. Electron spectroscopy for surface analysis - the ES300 electron spectrometer and its applications

    International Nuclear Information System (INIS)

    Walker, J.A.J.; Price, W.B.

    1980-07-01

    The features of the ES300 electron spectrometer are described together with factors which affect the energy spectrum, experimental variables and interpretation of the spectral information. A discussion of five applications illustrates the use of X-ray photo-electron spectroscopy (XPS) in the diverse work of the Risley Nuclear Power Development Laboratories (RNL). The analytical results are given for each of the examples and their interpretation discussed in the chemical context of the original problem. (author)

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

    DEFF Research Database (Denmark)

    Bork, Jakob

    tunneling microscope (STM). Especially at low temperatures the Kondo resonance is used to probe magnetic interaction with ferromagnetic islands and between two atoms. The latter showing a crossover between Kondo screened atoms and antiferromagnetically coupled atoms close to the quantum critical point....... This is related to research in correlated electron materials such as studies of phase transitions in heavy fermion compounds and magnetic interaction in spintronic research. The capping of cobalt islands on Cu(111) with silver is investigated with STM and photoemission spectroscopy. It is shown that at low...

  16. Design of nuclear spectroscopy electronics based on the EUROsystem standard

    International Nuclear Information System (INIS)

    Pahor, J.

    1987-11-01

    The development of modular nuclear instruments in the EUROcard system has been continued by the design of a staircase generator; such an instrument is needed for accurate testing of spectroscopy amplifiers. The generator provides very precisely defined steps with the period between them varying from 8 to 50 microseconds, the output voltage continuously variable from 2 to 5 V, and attenuated ion steps between 1 and 100. Great care was taken that individual steps exhibit no overshot, thus providing a very clean signal to the input of a tested amplifier. The circuitry is kept simple, and it can be easily constructed in any electronics laboratory. Figs

  17. Diode laser spectroscopy of oxygen electronic band at 760 nm

    International Nuclear Information System (INIS)

    Lucchesini, A.; De Rosa, M.; Gozzini, S.

    1998-01-01

    Collisional broadening and shift coefficients have been obtained by analyzing the line shapes of oxygen absorptions in the 760 nm electronic band. By using a diode laser spectrometer with commercially available etherostructure Al x Ga 1-x As diode lasers operating in 'free-running mode', line shape parameters have been collected at room temperature by varying the gas pressure. A systematic study has been carried on seven absorption lines by scanning the diode laser emission wavelength around the gas resonances. The weak absorption lines have been detected by using the wavelength modulation (WM) spectroscopy technique with second-harmonic detection

  18. 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.

  19. Inelastic electron tunneling spectroscopy of a single nuclear spin.

    Science.gov (United States)

    Delgado, F; Fernández-Rossier, J

    2011-08-12

    Detection of a single nuclear spin constitutes an outstanding problem in different fields of physics such as quantum computing or magnetic imaging. Here we show that the energy levels of a single nuclear spin can be measured by means of inelastic electron tunneling spectroscopy (IETS). We consider two different systems, a magnetic adatom probed with scanning tunneling microscopy and a single Bi dopant in a silicon nanotransistor. We find that the hyperfine coupling opens new transport channels which can be resolved at experimentally accessible temperatures. Our simulations evince that IETS yields information about the occupations of the nuclear spin states, paving the way towards transport-detected single nuclear spin resonance.

  20. 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......, dimer with nanometer-sized gaps, core-shell nanowire with ultrathin metal shell, and a thin metal film. In all cases we compare the nonlocal models with the local-response approximation. Below the plasma frequency, we find that the distance between the induced positive and negative surface charges...

  1. Electron energy-loss spectroscopy on fullerenes and fullerene compounds

    International Nuclear Information System (INIS)

    Armbruster, J.

    1996-03-01

    A few years ago, a new form of pure carbon, the fullerenes, has been discovered, which shows many fascinating properties. Within this work the spatial and electronic structure of some selected fullerene compounds have been investigated by electron-energy-loss spectroscopy in transmission. Phase pure samples of alkali intercalated fullerides A x C 60 (A=Na, K, Cs) have been prepared using vacuum distillation. Measruements of K 3 C 60 show a dispersion of the charge carrier plasmon close to zero. This can be explained by calculations, which take into account both band structure and local-field (inhomogeneity) effects. The importance of the molecular structure can also be seen from the A 4 C 60 compounds, where the non-metallic properties are explained by a splitting of the t 1u and t 1g derived bands that is caused by electron-correlation and Jahn-Teller effects. First measurements of the electronic structure of Na x C 60 (x>6) are presented and reveal a complete transfer from the sodium atoms but an incomplete transfer onto the C 60 molecules. This behaviour can be explained by taking into account additional electronic states that are situated between the sodium atoms in the octahedral sites and are predicted by calculations using local density approximation. The crystal structure of the higher fullerenes C 76 and C 84 is found to be face-centered cubic

  2. Characterization of functional LB films using electron spin resonance spectroscopy

    International Nuclear Information System (INIS)

    Kuroda, Shin-ichi

    1995-01-01

    The role of ESR spectroscopy in the characterization of functional LB films is discussed. Unpaired electrons in LB films are associated with isolated radical molecules produced by charge transfer, paramagnetic metallic ions such as Cu 2+ , strongly interacting spins in the mixed valence states in charge-transfer salts, and so on. These spins often manifest the functions of materials. They can also act as microscopic probes in the ESR analysis devoted for the elucidation of characteristic properties of LB films. In structural studies, ESR is of particular importance in the analysis of molecular orientation of LB films. ESR can unambiguously determine the orientation of molecules through g-value anisotropy: different g value, different resonance field. Two types of new control methods of molecular orientation in LB films originated from the ESR analysis: study of in-plane orientation in dye LB films which led to the discovery of flow-orientation effect, and observation of drastic change of orientation of Cu-porphyrin in LB films using the trigger molecule, n-hexatriacontane. In the studies of electronic properties, hyperfine interactions between electron and nuclear spins provide information about molecular orbitals and local structures. Stable isotopes have been successfully applied to the stable radicals in merocyanine LB films to identify hyperfine couplings. In conducting LB films composed of charge-transfer salts, quasi-one-dimensional antiferromagnetism in semiconducting films and spin resonance of conduction electrons in metallic films are observed. Results provide microscopic evidence for the development of columnar structures of constituent molecules. Development of new functional LB films may provide more cases where ESR spectroscopy will clarify the nature of such films. (author)

  3. 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.

  4. Atomic column resolved electron energy-loss spectroscopy

    International Nuclear Information System (INIS)

    Duscher, G.; Pennycook, S.J.; Browning, N.D.

    1998-01-01

    Spatially resolved electron energy-loss spectroscopy (EELS) is rapidly developing into a unique and powerful tool to characterize internal interfaces. Because atomic column resolved Z-contrast imaging can be performed simultaneously with EELS in the scanning transmission electron microscope, this combination allows the atomic structure to be correlated with the electronic structure, and thus the local properties of interfaces or defects can be determined directly. However, the ability to characterize interfaces and defects at that level requires not only high spatial resolution but also the exact knowledge of the beam location, from where the spectrum is obtained. Here we discuss several examples progressing from cases where the limitation in spatial resolution is given by the microscopes or the nature of the sample, to one example of impurity atoms at a grain boundary, which show intensity and fine structure changes from atomic column to atomic column. Such data can be interpreted as changes in valence of the impurity, depending on its exact site in the boundary plane. Analysis ofthis nature is a valuable first step in understanding the microscopic structural, optical and electronic properties of materials. (orig.)

  5. Selectivity of alkyl radical formation from branched alkanes studied by electron spin resonance and electron spin echo spectroscopy

    International Nuclear Information System (INIS)

    Tsuneki, Ichikawa; Hiroshi, Yoshida

    1992-01-01

    Alkyl radicals generated from branched alkanes by γ radiation are being measuring by electron spin resonance and electron spin echo spectroscopy. This research is being conducted to determine the mechanism of selective alkyl radical formation in low-temperature solids

  6. Angular distribution of scattered electron and medium energy electron spectroscopy for metals

    International Nuclear Information System (INIS)

    Oguri, Takeo; Ishioka, Hisamichi; Fukuda, Hisashi; Irako, Mitsuhiro

    1986-01-01

    The angular distribution (AD) of scattered electrons produced by medium energy incident electrons (E P = 50 ∼ 300 eV) from polycrystalline Ti, Fe, Ni, Cu and Au were obtained by the angle-resolved medium energy electron spectrometer. The AD of the energy loss peaks are similar figures to AD of the elastically reflected electron peaks. Therefore, the exchanged electrons produced by the knock-on collision between the incident electrons and those of metals without momentum transfer are observed as the energy loss spectra (ELS). This interpretation differs from the inconsequent interpretation by the dielectric theory or the interband transition. The information depth and penetration length are obtained from AD of the Auger electron peaks. The contribution of the surface to spectra is 3 % at the maximum for E P = 50 eV. The true secondary peaks representing the secondary electron emission spectroscopy (SES) are caused by the emissions of the energetic electrons (kT e ≥ 4 eV), and SES is the inversion of ELS. The established fundamental view is that the medium energy electron spectra represent the total bulk density of states. (author)

  7. Gas flow counter conversion electron Moessbauer spectroscopy (GFC-CEMS)

    International Nuclear Information System (INIS)

    Williamson, A.; Vijay, Y.K.; Jain, I.P.

    1999-01-01

    Conversion Electron Moessbauer Spectroscopy (CEMS) is well established technique to study surface properties of materials. However non availability of commercial experimental set up and complexity of operational parameters have been restricting the working experimental groups with in the country and abroad. In this paper we have presented the development work for the design of Gas Flow Counter (GFC), e.g. convenient sample mount, grounding, steady flow rate adjustment and minimum He-losses so that the detector operation and installation becomes convenient and dependable. The basic design is modified e.g. large volume to maintain steady gas flow, sample mount close to central wire and O-ring fitted flange. The CEMS spectra are recorded using conventional Moessbauer drive and 57 Co source. The calibrated spectrum shows a detection efficiency of about 20% for natural iron and steel foil. The CEMS spectrum for FeTi bulk and transmission Moessbauer Spectroscopy (TMS) spectrum of FeTi thin film deposited by vacuum evaporation on thin glass substrate were recorded to test the performance of GFC-CEMS. (author)

  8. Electronic structure of atoms: atomic spectroscopy information system

    International Nuclear Information System (INIS)

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

    2017-01-01

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

  9. 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.

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

    International Nuclear Information System (INIS)

    Chawla, S.P.; Thomas, Paul

    2004-01-01

    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)

  11. Ballistic electron emission spectroscopy on Ag/Si devices

    Energy Technology Data Exchange (ETDEWEB)

    Bannani, A; Bobisch, C A; Matena, M; Moeller, R [Department of Physics, Center for Nanointegration Duisburg-Essen, University of Duisburg-Essen, 47048 Duisburg (Germany)], E-mail: amin.bannani@uni-due.de

    2008-09-17

    In this work we report on ballistic electron emission spectroscopy (BEES) studies on epitaxial layers of silver grown on silicon surfaces, with either a Si(111)-(7 x 7) or Si(100)-(2 x 1) surface reconstruction. The experiments were done at low temperature and in ultra-high vacuum (UHV). In addition, BEES measurements on polycrystalline Ag films grown on hydrogen-terminated H:Si(111)-(1 x 1) and H:Si(100)-(2 x 1) surfaces were performed. The Schottky barrier heights were evaluated by BEES. The results are compared to the values for the barrier height reported for macroscopic Schottky diodes. We show that the barrier heights for the epitaxial films substantially differ from the values measured on polycrystalline Ag films, suggesting a strong effect of the interface on the barrier height.

  12. Electronic structure of atoms: atomic spectroscopy information system

    Science.gov (United States)

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

    2017-10-01

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

  13. Determination of the electron-electron collisional frequency by means of plasma electron spectroscopy

    International Nuclear Information System (INIS)

    Kolokolov, N.B.; Kudryavtsev, A.A.; Romanenko, V.A.

    1989-01-01

    Methods of controlling fast part of electron distribution function (DF) in nonlocal regime of current-free plasma are suggested and realized. Artificially created step in DF fast part has a simple link with frequencies of electron-electron and elastic electron-atom collisions that may be defined in the corresponding experiments

  14. Use of analytical electron microscopy and auger electron spectroscopy for evaluating materials

    International Nuclear Information System (INIS)

    Jones, R.H.; Bruemmer, S.M.; Thomas, M.T.; Baer, D.R.

    1982-11-01

    Analytical electron microscopy (AEM) can be used to characterize the microstructure and microchemistry of materials over dimensions less than 10 nm while Auger electron spectroscopy (AES) can be used to characterize the chemical composition of surfaces and interfaces to a depth of less than 1 nm. Frequently, the information gained from both instruments can be coupled to give new insight into the behavior of materials. Examples of the use of AEM and AES to characterize segregation, sensitization and radiation damage are presented. A short description of the AEM and AES techniques are given

  15. Secondary electron emission studied by secondary electron energy loss coincidence spectroscopy (SE2ELCS)

    International Nuclear Information System (INIS)

    Khalid, R.

    2013-01-01

    Emission of secondary electrons is of importance in many branches of fundamental and applied science. It is widely applied in the electron microscope for the investigation of the structure and electronic state of solid surfaces and particle detection in electron multiplier devices, and generally it is related to the energy dissipation of energetic particles moving inside a solid. The process of secondary electron emission is a complex physical phenomenon, difficult to measure experimentally and treat theoretically with satisfactory accuracy. The secondary electron spectrum measured with single electron spectroscopy does not provide detailed information of the energy loss processes responsible for the emission of secondary electrons. This information can be accessed when two correlated electron pairs are measured in coincidence and the pair consists of a backscattered electron after a given energy loss and a resulting emitted secondary electron. To investigate the mechanisms responsible for the emission of secondary electrons, a reflection (e,2e) coincidence spectrometer named Secondary Electron Electron Energy Loss Coincidence Spectrometer (SE2ELCS) has been developed in the framework of this thesis which allows one to uncover the relation between the features in the spectra which are due to energy losses and true secondary electron emission structures. The correlated electron pairs are measured with a hemispherical mirror analyzer (HMA) and a time of flight analyzer (TOF) by employing a continuous electron beam. An effort has been made to increase the coincidence count rate by increasing the effective solid angle of the TOF analyzer and optimizing the experimental parameters to get optimum energy resolution. Double differential coincidence spectra for a number of materials namely, nearly free electron metals (Al, Si), noble metals (Ag, Au, Cu, W) and highly oriented pyrolytic graphite (HOPG) have been measured using this coincidence spectrometer. The

  16. Analysis of quantum semiconductor heterostructures by ballistic electron emission spectroscopy

    Science.gov (United States)

    Guthrie, Daniel K.

    1998-09-01

    The microelectronics industry is diligently working to achieve the goal of gigascale integration (GSI) by early in the 21st century. For the past twenty-five years, progress toward this goal has been made by continually scaling down device technology. Unfortunately, this trend cannot continue to the point of producing arbitrarily small device sizes. One possible solution to this problem that is currently under intensive study is the relatively new area of quantum devices. Quantum devices represent a new class of microelectronic devices that operate by utilizing the wave-like nature (reflection, refraction, and confinement) of electrons together with the laws of quantum mechanics to construct useful devices. One difficulty associated with these structures is the absence of measurement techniques that can fully characterize carrier transport in such devices. This thesis addresses this need by focusing on the study of carrier transport in quantum semiconductor heterostructures using a relatively new and versatile measurement technique known as ballistic electron emission spectroscopy (BEES). To achieve this goal, a systematic approach that encompasses a set of progressively more complex structures is utilized. First, the simplest BEES structure possible, the metal/semiconductor interface, is thoroughly investigated in order to provide a foundation for measurements on more the complex structures. By modifying the semiclassical model commonly used to describe the experimental BEES spectrum, a very complete and accurate description of the basic structure has been achieved. Next, a very simple semiconductor heterostructure, a Ga1-xAlxAs single-barrier structure, was measured and analyzed. Low-temperature measurements on this structure were used to investigate the band structure and electron-wave interference effects in the Ga1-xAlxAs single barrier structure. These measurements are extended to a simple quantum device by designing, measuring, and analyzing a set of

  17. Attosecond photoelectron spectroscopy of electron transport in solids

    International Nuclear Information System (INIS)

    Magerl, Elisabeth

    2011-01-01

    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. 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

  19. Transfer of spectral weight in spectroscopies of correlated electron systems

    International Nuclear Information System (INIS)

    Rozenberg, M.J.; Kotliar, G.; Kajueter, H.

    1996-01-01

    We study the transfer of spectral weight in the photoemission and optical spectra of strongly correlated electron systems. Within the local impurity self-consistent approximation, that becomes exact in the limit of large lattice coordination, we consider and compare two models of correlated electrons, the Hubbard model and the periodic Anderson model. The results are discussed in regard to recent experiments. In the Hubbard model, we predict an anomalous enhancement optical spectral weight as a function of temperature in the correlated metallic state which is in qualitative agreement with optical measurements in V 2 O 3 . We argue that anomalies observed in the spectroscopy of the metal are connected to the proximity to a crossover region in the phase diagram of the model. In the insulating phase, we obtain excellent agreement with the experimental data, and present a detailed discussion on the role of magnetic frustration by studying the k-resolved single-particle spectra. The results for the periodic Anderson model are discussed in connection to recent experimental data of the Kondo insulators Ce 3 Bi 4 Pt 3 and FeSi. The model can successfully explain the thermal filling of the optical gap and the corresponding changes in the photoemission density of states. The temperature dependence of the optical sum rule is obtained, and its relevance to the interpretation of the experimental data discussed. Finally, we argue that the large scattering rate measured in Kondo insulators cannot be described by the periodic Anderson model. copyright 1996 The American Physical Society

  20. Recent advances in ion and electron spectroscopy of polymer surfaces

    Science.gov (United States)

    Gardella, Joseph A.

    1988-01-01

    The structure of microdomains and bonding at multicomponent polymer material interfaces has been studied using a variety of surface sensitive spectroscopic techniques. In our laboratory, low energy ion scattering spectroscopy (ISS) and static secondary ion mass spectrometry (SIMS) serve to complement results from angular dependent X-ray photoelectron spectroscopy (XPS or ESCA), Fourier transform infrared (FTIR) with attenuated total reflectance (ATR) sampling and SEM techniques to provide a quantitative picture of the relationships between structure, bonding, morphology and microdomain formation in near surface regions of polymeric systems. The added surface sensitivity of ISS can yield quantitative information at a sampling depth of 3-5 Å, which, with ESCA and FTIR analysis yields a "non-destructive" depth profile of domain formation in copolymer and blend systems. These studies will be illustrated with results from siloxane and siloxane/polycarbonate copolymer systems, where a complete picture of surface domain formation and morphology as a function of composition and polymer crystallinity has been developed. ISS can also yield information regarding the orientation of surface functional groups which ESCA and FTIR do not have either sensitivity and/or sufficient detection limits to analyze. These studies will be illustrated by the analysis of plasma hydrolysis/oxidation of stereoregular poly(methyl-methacrylate). The effects of functional group orientation on reactivity will be explored using results from ISS, ESCA and FTIR for stereoregular (isotatic, syndiotactic) and random (atactic) PMMA. Electron energy loss spectroscopy at high resolution (HREELS) has recently been extended to the examination of polymer and organic surfaces. Vibrational information from this experiment can yield very precise results about surface functional groups (1-20 Å) but at much lower resolution than is typical from IR and Raman techniques. However, the promise of evaluating surface

  1. Electron beam interactions with CO on W[100] studied by Auger electron spectroscopy

    International Nuclear Information System (INIS)

    Housley, M.; King, D.A.

    1977-01-01

    The interaction of 2500 eV electrons with carbon monoxide chemisorbed on tungsten [100] was investigated by rapid-scan Auger electron spectroscopy. When no α state was present the O and C signals from the β state of CO were invariant during electron bombardment, giving an upper limit estimate for the electron stimulated desorption cross section, Qsub(β), of 2 x 10 -21 cm 2 . With the crystal at room temperature and saturated with CO, however, electron-beam induced accumulation of carbon was observed and characterised, the rate of the process being independent of CO pressure at pressures above 2 x 10 -8 Torr. At 450 K the rate was found to be pressure dependent up to at least 6 x 10 -7 Torr. A model is proposed for the accumulation process, which is based on electron beam dissociation of α 2 -CO to form adsorbed carbon and gaseous O and the creation of new sites for further α 2 -CO adsorption; it is in quantitative agreement with the results and yields a cross section for ESD of α 2 -CO (Qsub(α 2 )=1.55 X 10 -18 cm 2 ) in clo 2 e agreement with direct measurements. (Auth.)

  2. Studies of ultrathin magnetic films and particle-surface interactions with spin-sensitive electron spectroscopies

    International Nuclear Information System (INIS)

    Walters, G.K.; Dunning, F.B.

    1991-06-01

    Research during the current grant year has focused on: Investigation of probing depth in electron scattering from epitaxially grown paramagnetic films by means of Spin-Polarized Electron Energy Loss Spectroscopy; and studies of the dynamics of metastable He(2 3 S) deexcitation at surfaces utilizing Spin-Polarized Metastable Deexcitation Spectroscopy . This report discussed this research

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

    Science.gov (United States)

    Mishra, P.; Lohani, H.; Kundu, A. K.; Patel, R.; Solanki, G. K.; Menon, Krishnakumar S. R.; Sekhar, B. R.

    2015-07-01

    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.

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

    International Nuclear Information System (INIS)

    Mishra, P; Lohani, H; Sekhar, B R; Kundu, A K; Menon, Krishnakumar S R; Patel, R; Solanki, G K

    2015-01-01

    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 4p z 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)

  5. Many-electron effect in the resonant Auger electron spectroscopy spectra of adsorbates

    International Nuclear Information System (INIS)

    Ohno, Masahide

    2007-01-01

    It is shown by a many-body theory that a resonantly excited core hole state in a chemisorbed molecule such as CO/Ni, CO/Pd, and CO/Pt relaxes to a fully relaxed one, i.e., the ionized core hole state of the smallest binding energy observed by photoelectron spectroscopy, before the core hole decays so that the resonant Auger electron spectroscopy (RAES) spectrum shows the normal Auger decay spectrum. It is shown by a many-body theory that the Auger peaks on the higher kinetic energy (K.E.) side in the RAES or AES spectrum, i.e., so called back-bonding peaks, are the two-hole states consisting of a valence hole and a hole in the adsorbate-substrate hybrid states below the substrate Fermi level. The latter hole is the change in the density of the hybrid states occupied by the screening electron from the core hole state to the valence-hole state. The difference between the back-bonding peak energy and the single valence-hole energy provides an important information about the change in the density of the hybrid states occupied by the screening electron from the core hole state to the valence-hole state. The difference between the RAES spectrum measured at the resonance energy and the AES spectrum measured at far above the ionization limit shows the competition between relaxation and decay of shakeup satellites such as the charge transfer (CT) shakeup. The relaxation rate of the CT shakeup state can be determined by Auger-photoelectron coincidence spectroscopy (APECS)

  6. Electronic structure of EuN: Growth, spectroscopy, and theory

    DEFF Research Database (Denmark)

    Richter, J. H.; Ruck, B.J.; Simpson, M.

    2011-01-01

    and the lowest-lying 8S multiplet. The Hubbard-I model is also in good agreement with purely atomic multiplet calculations for the Eu M-edge XAS. LSDA+U and DMFT calculations find a metallic ground state, while QSGW results predict a direct band gap at X for EuN of about 0.9 eV that matches closely an absorption...... and QSGW models capture the density of conduction band states better than does LSDA+U. Only the Hubbard-I model contains a correct description of the Eu 4f atomic multiplets and locates their energies relative to the band states, and we see some evidence in XAS for hybridization between the conduction band...... edge seen in optical transmittance at 0.9 eV, and a smaller indirect gap. Overall, the combination of theoretical methods and spectroscopies provides insights into the complex nature of the electronic structure of this material. The results imply that EuN is a narrow-band-gap semiconductor that lies...

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

    International Nuclear Information System (INIS)

    Griffith, G.W.

    1982-09-01

    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. Spectroscopy of hexafluorides with an odd number of electrons

    International Nuclear Information System (INIS)

    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 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 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 6 in order to resolve for the first time its fine rotational structure. (author)

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

    Energy Technology Data Exchange (ETDEWEB)

    Yedra, Ll.; Estradé, S., E-mail: sestrade@ub.edu [LENS, MIND-IN2UB, Departament d' Electrònica, Universitat de Barcelona, Martí i Franquès 1, 08028 Barcelona (Spain); TEM-MAT, CCiT, Universitat de Barcelona, Solé i Sabarís 1, 08028 Barcelona (Spain); Torruella, P.; Eljarrat, A.; Peiró, F. [LENS, MIND-IN2UB, Departament d' Electrònica, Universitat de Barcelona, Martí i Franquès 1, 08028 Barcelona (Spain); Darbal, A. D. [AppFive LLC, 1095 W Rio Salado Pkway, Suite 110, Tempe, Arizona 85281 (United States); Weiss, J. K. [AppFive LLC, 1095 W Rio Salado Pkway, Suite 110, Tempe, Arizona 85281 (United States); NanoMEGAS SPRL, Blvd. Edmond Machtens 79, B-1080 Brussels (Belgium)

    2014-08-04

    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.

  10. 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)

  11. 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)

  12. Electron energy loss spectroscopy microanalysis and imaging in the transmission electron microscope: example of biological applications

    International Nuclear Information System (INIS)

    Diociaiuti, Marco

    2005-01-01

    This paper reports original results obtained in our laboratory over the past few years in the application of both electron energy loss spectroscopy (EELS) and electron spectroscopy imaging (ESI) to biological samples, performed in two transmission electron microscopes (TEM) equipped with high-resolution electron filters and spectrometers: a Gatan model 607 single magnetic sector double focusing EEL serial spectrometer attached to a Philips 430 TEM and a Zeiss EM902 Energy Filtering TEM. The primary interest was on the possibility offered by the combined application of these spectroscopic techniques with those offered by the TEM. In particular, the electron beam focusing available in a TEM allowed us to perform EELS and ESI on very small sample volumes, where high-resolution imaging and electron diffraction techniques can provide important structural information. I show that ESI was able to improve TEM performance, due to the reduced chromatic aberration and the possibility of avoiding the sample staining procedure. Finally, the analysis of the oscillating extended energy loss fine structure (EXELFS) beyond the ionization edges characterizing the EELS spectra allowed me, in a manner very similar to the extended X-ray absorption fine structure (EXAFS) analysis of the X-ray absorption spectra, to obtain short-range structural information for such light elements of biological interest as O or Fe. The Philips EM430 (250-300 keV) TEM was used to perform EELS microanalysis on Ca, P, O, Fe, Al and Si. The assessment of the detection limits of this method was obtained working with well-characterized samples containing Ca and P, and mimicking the actual cellular matrix. I applied EELS microanalysis to Ca detection in bone tissue during the mineralization process and to P detection in the cellular membrane of erythrocytes treated with an anti-tumoral drug, demonstrating that the cellular membrane is a drug target. I applied EELS microanalysis and selected area electron

  13. Mass spectroscopy of recoiled ions, secondary ion mass spectroscopy, and Auger electron spectroscopy investigation of Y2O3-stabilized ZrO2(100) and (110)

    International Nuclear Information System (INIS)

    Herman, G.S.; Henderson, M.A.; Starkweather, K.A.; McDaniel, E.P.

    1999-01-01

    We have studied the (100) and (110) surfaces of yttria-stabilized cubic ZrO 2 using Auger electron spectroscopy, low energy electron diffraction (LEED), direct recoil spectroscopy, mass spectroscopy of recoiled ions (MSRI), and secondary ion mass spectroscopy (SIMS). The concentration of yttrium at the surface was weakly influenced by the surface structure under the experimental conditions investigated. Both MSRI and SIMS indicated a more enhanced yttrium signal than zirconium signal at the surface compared to the respective bulk concentrations. The surfaces were not very well ordered as indicated by LEED. The yttria-stabilized cubic ZrO 2 single crystal surfaces may not be a suitable model material for pure phase ZrO 2 surfaces due to significant yttria concentrations at the surface. copyright 1999 American Vacuum Society

  14. Modelling high-resolution electron microscopy based on core-loss spectroscopy

    International Nuclear Information System (INIS)

    Allen, L.J.; Findlay, S.D.; Oxley, M.P.; Witte, C.; Zaluzec, N.J.

    2006-01-01

    There are a number of factors affecting the formation of images based on core-loss spectroscopy in high-resolution electron microscopy. We demonstrate unambiguously the need to use a full nonlocal description of the effective core-loss interaction for experimental results obtained from high angular resolution electron channelling electron spectroscopy. The implications of this model are investigated for atomic resolution scanning transmission electron microscopy. Simulations are used to demonstrate that core-loss spectroscopy images formed using fine probes proposed for future microscopes can result in images that do not correspond visually with the structure that has led to their formation. In this context, we also examine the effect of varying detector geometries. The importance of the contribution to core-loss spectroscopy images by dechannelled or diffusely scattered electrons is reiterated here

  15. 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.

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

    International Nuclear Information System (INIS)

    Ferreira da Silva, F.; Lange, E.; Limão-Vieira, P.; Jones, N. C.; Hoffmann, S. V.; Hubin-Franskin, M.-J.; Delwiche, J.; Brunger, M. J.

    2015-01-01

    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. Coincident Auger electron and recoil ion momentum spectroscopy for low-energy ion-atom collisions

    International Nuclear Information System (INIS)

    Laurent, G.; Tarisien, M.; Flechard, X.; Jardin, P.; Guillaume, L.; Sobocinski, P.; Adoui, L.; Bordenave-Montesquieu, A.; Bordenave-Montesquieu, D.; Chesnel, J.-Y.; Fremont, F.; Hennecart, D.; Lienard, E.; Maunoury, L.; Moretto-Capelle, P.; Cassimi, A.

    2003-01-01

    The recoil ion momentum spectroscopy (RIMS) method combined with the detection of Auger electrons has been used successfully to analyse double electron capture following O 6+ + He collisions at low impact velocities. Although RIMS and Auger spectroscopies are known to be efficient tools to obtain details on the primary processes occurring during the collision, the conjunction of both techniques provides new insights on the electron capture process. In the present experiment, triple coincidence detection of the scattered projectile, the target recoil ion and the Auger electron allows for a precise identification of the doubly excited states O 4+ (1s 2 nln ' l ' ) populated after double electron-capture events

  19. 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

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

    International Nuclear Information System (INIS)

    Tahir, Dahlang; Kraaer, Jens; Tougaard, Sven

    2014-01-01

    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.

  1. Temperature-dependent surface structure, composition, and electronic properties of the clean SrTiO3(111) crystal face: Low-energy-electron diffraction, Auger-electron spectroscopy, electron energy loss, and ultraviolet-photoelectron spectroscopy studies

    International Nuclear Information System (INIS)

    Lo, W.J.; Somorjai, G.A.

    1978-01-01

    Low-energy-electron diffraction, Auger-electron spectroscopy, electron-energy-loss, and ultraviolet-photoelectron spectroscopies were used to study the structure, composition, and electron energy distribution of a clean single-crystal (111) face of strontium titanate (perovskite). The dependence of the surface chemical composition on the temperature has been observed along with corresponding changes in the surface electronic properties. High-temperature Ar-ion bombardment causes an irreversible change in the surface structure, stoichiometry, and electron energy distribution. In contrast to the TiO 2 surface, there are always significant concentrations of Ti 3+ in an annealed ordered SrTiO 3 (111) surface. This stable active Ti 3+ monolayer on top of a substrate with large surface dipole potential makes SrTiO 3 superior to TiO 2 when used as a photoanode in the photoelectrochemical cell

  2. Electron spectroscopy studies of argon K-shell excitation and vacancy cascades

    International Nuclear Information System (INIS)

    Southworth, S.H.; MacDonald, M.A.; LeBrun, T.; Azuma, Y.; Cooper, J.W.

    1995-01-01

    Electron spectroscopy combined with tunable synchrotron radiation has been used for studies of Ar K-shell excitation and vacancy decay processes. In addition, electrons and fluorescent X-rays have been recorded in coincidence to select subsets of the ejected electron spectra. Examples are presented for Ar 1s photoelectrons and KLL and LMM Auger spectra

  3. Time dependent thermal treatment of oxidized MWCNTs studied by the electron and mass spectroscopy methods

    Czech Academy of Sciences Publication Activity Database

    Stobinski, L.; Lesiak, B.; Zemek, Josef; Jiříček, Petr

    2012-01-01

    Roč. 258, č. 20 (2012), s. 7912-7917 ISSN 0169-4332 Institutional research plan: CEZ:AV0Z10100521 Keywords : MWCNTs * ox-MWCNTs * functional materials * electron spectroscopy * mass spectroscopy Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.112, year: 2012

  4. Studies on low energy ion-atom collisions by means of electron-spectroscopy

    International Nuclear Information System (INIS)

    Hirosi Suzuki

    1991-01-01

    The typical results of studies on autoionization processes produced by low energy ion-atom collisions are given by means of the ejected electron spectroscopy, which have been performed by Atomic Physics Group of Sophia University

  5. Electronic properties of Mn-phthalocyanine–C60 bulk heterojunctions: Combining photoemission and electron energy-loss spectroscopy

    International Nuclear Information System (INIS)

    Roth, Friedrich; Herzig, Melanie; Knupfer, Martin; Lupulescu, Cosmin; Darlatt, Erik; Gottwald, Alexander; Eberhardt, Wolfgang

    2015-01-01

    The electronic properties of co-evaporated mixtures (blends) of manganese phthalocyanine and the fullerene C 60 (MnPc:C 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 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 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 60 to MnPc thin films

  6. Electron emission relevant to inner-shell photoionization of condensed water studied by multi-electron coincidence spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Hikosaka, Y., E-mail: hikosaka@las.u-toyama.ac.jp [Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama 930-0194 (Japan); Mashiko, R.; Konosu, Y.; Soejima, K. [Department of Environmental Science, Niigata University, Niigata 950-2181 (Japan); Shigemasa, E. [UVSOR Facility, Institute for Molecular Science, Okazaki 444-8585 (Japan); SOKENDAI, Okazaki 444-8585 (Japan)

    2016-11-15

    Highlights: • Multi-electron coincidence spectroscopy is applied to the study of electron emissions from condensed H2O molecules. • Coincidence Auger spectra are obtained for different photoelectron energies. • The energy distribution of the slow electrons ejected in the Auger decay is deduced from three-fold coincidences. - Abstract: Multi-electron coincidence spectroscopy using a magnetic-bottle electron spectrometer has been applied to the study of the Auger decay following O1s photoionization of condensed H{sub 2}O molecules. Coincidence Auger spectra are obtained for three different photoelectron energy ranges. In addition, the energy distribution of the slow electrons ejected in the Auger decay of the O1s core hole is deduced from three-fold coincidences.

  7. Electron spectroscopy using a multi-detector array

    International Nuclear Information System (INIS)

    Butler, P.A.; Cann, K.J.; Trzaska, W.H.

    1996-01-01

    A description is given of the novel electron spectrometer SACRED, which uses a multi-element Si array to detect cascades of conversion electrons. Its application to the study of deformed structures in 222 Th is described. (orig.)

  8. 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

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

    International Nuclear Information System (INIS)

    Zhou, X.J.

    2010-01-01

    In addition to the record high superconducting transition temperature (T c ), high temperature cuprate superconductors are characterized by their unusual superconducting properties below T c , and anomalous normal state properties above T 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 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 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 thought possible

  10. In-beam conversion electron spectroscopy using the SACRED array

    International Nuclear Information System (INIS)

    Jones, P.M.; Cann, K.J.; Cocks, J.F.C.; Jones, G.D.; Julin, R.; Schulze, B.; Smith, J.F.; Wilson, A.N.

    1997-01-01

    Conversion electron studies of medium-heavy to heavy nuclear mass systems are important where the internal conversion process begins to dominate over gamma-ray emission. The use of a segmented detector array sensitive to conversion electrons has been used to study multiple conversion electron cascades from nuclear transitions. The application of the silicon array for conversion electron detection (SACRED) for in-beam measurements has successfully been implemented. (orig.). With 2 figs

  11. Growth and trends in Auger-electron spectroscopy and x-ray photoelectron spectroscopy for surface analysis

    International Nuclear Information System (INIS)

    Powell, C.J.

    2003-01-01

    A perspective is given of the development and use of surface analysis, primarily by Auger-electron spectroscopy (AES) and x-ray photoelectron spectroscopy (XPS), for solving scientific and technological problems. Information is presented on growth and trends in instrumental capabilities, instrumental measurements with reduced uncertainties, knowledge of surface sensitivity, and knowledge and effects of sample morphology. Available analytical resources are described for AES, XPS, and secondary-ion mass spectrometry. Finally, the role of the American Vacuum Society in stimulating improved surface analyses is discussed

  12. Auger electron spectroscopy analysis of high metal content micro-structures grown by electron beam induced deposition

    International Nuclear Information System (INIS)

    Cicoira, F.; Hoffmann, P.; Olsson, C.O.A.; Xanthopoulos, N.; Mathieu, H.J.; Doppelt, P.

    2005-01-01

    An auger electron spectroscopy study was carried out on Rh-containing micro-structures grown by electron beam induced deposition (EBID) of the iso-structural and iso-electronic precursors [RhCl(PF 3 ) 2 ] 2 and [RhCl(CO) 2 ] 2 . A material containing between 55 and 60 at.% Rh was obtained from both precursors. The chemical composition of structures grown from the two different precursors indicates a similar decomposition mechanism. Deposits grown from [RhCl(PF 3 ) 2 ] 2 showed a chemical composition independent of electron energy and electron dose in the investigated range of conditions

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

    International Nuclear Information System (INIS)

    Guo, X.; Canney, S.; Kheifets, A.S.; Vos, M.; Fang, Z.; Utteridge, S.; McCarthy, I.E.; Weigold, E.

    1996-09-01

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

  14. Status of the development of electron volt inelastic neutron spectroscopy

    International Nuclear Information System (INIS)

    Newport, R.J.; Taylor, A.D.; Williams, W.G.

    1984-05-01

    High energy inelastic neutron scattering spectroscopy is reviewed in the light of material presented at the 'High Energy Excitations in Condensed Matter' (HEECM) Workshop, held at Los Alamos National Laboratory 13-15 February 1984. Particular attention is paid to the development of instrumentation based on nuclear resonance analysers. (author)

  15. Development of an Apparatus for High-Resolution Auger Photoelectron Coincidence Spectroscopy (APECS) and Electron Ion Coincidence (EICO) Spectroscopy

    Science.gov (United States)

    Kakiuchi, Takuhiro; Hashimoto, Shogo; Fujita, Narihiko; Mase, Kazuhiko; Tanaka, Masatoshi; Okusawa, Makoto

    We have developed an electron electron ion coincidence (EEICO) apparatus for high-resolution Auger photoelectron coincidence spectroscopy (APECS) and electron ion coincidence (EICO) spectroscopy. It consists of a coaxially symmetric mirror electron energy analyzer (ASMA), a miniature double-pass cylindrical mirror electron energy analyzer (DP-CMA), a miniature time-of-flight ion mass spectrometer (TOF-MS), a magnetic shield, an xyz stage, a tilt-adjustment mechanism, and a conflat flange with an outer diameter of 203 mm. A sample surface was irradiated by synchrotron radiation, and emitted electrons were energy-analyzed and detected by the ASMA and the DP-CMA, while desorbed ions were mass-analyzed and detected by the TOF-MS. The performance of the new EEICO analyzer was evaluated by measuring Si 2p photoelectron spectra of clean Si(001)-2×1 and Si(111)-7×7, and by measuring Si-L23VV-Si-2p Auger photoelectron coincidence spectra (Si-L23VV-Si-2p APECS) of clean Si(001)-2×1.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-09-01

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

  17. Efficient spin transitions in inelastic electron tunneling spectroscopy.

    Science.gov (United States)

    Lorente, Nicolás; Gauyacq, Jean-Pierre

    2009-10-23

    The excitation of the spin degrees of freedom of an adsorbed atom by tunneling electrons is computed using strong coupling theory. Recent measurements [Heinrich, Science 306, 466 (2004)] reveal that electron currents in a magnetic system efficiently excite its magnetic moments. Our theory shows that the incoming electron spin strongly couples with that of the adsorbate so that memory of the initial spin state is lost, leading to large excitation efficiencies. First-principles transmissions are evaluated in quantitative agreement with the experiment.

  18. Development of an Electron-Positron Source for Positron Annihilation Lifetime Spectroscopy

    Science.gov (United States)

    2009-12-19

    REPORT Development of an electron- positron source for positron annihilation lifetime spectroscopy : FINAL REPORT 14. ABSTRACT 16. SECURITY...to generate radiation, to accelerate particles, and to produce electrons and positrons from vacuum. From applications using existing high-repetition...theoretical directions. This report reviews work directed toward the application of positron generation from laser interaction with matter 1. REPORT DATE

  19. X-ray spectroscopy of highly-ionized atoms in an electron beam ion trap (EBIT)

    International Nuclear Information System (INIS)

    Marrs, R.E.; Bennett, C.; Chen, M.H.

    1988-01-01

    An Electron Beam Ion Trap at Lawrence Livermore National Laboratory is being used to produce and trap very-highly-charged-ions (q /le/ 70+) for x-ray spectroscopy measurements. Recent measurements of dielectronic recombination, electron impact excitation and transition energies are presented. 15 refs., 12 figs., 1 tab

  20. Status of electron temperature and density measurement with beam emission spectroscopy on thermal helium at TEXTOR

    NARCIS (Netherlands)

    Schmitz, O.; Beigman, I. L.; Vainshtein, L. A.; Schweer, B.; Kantor, M.; Pospieszczyk, A.; Xu, Y.; Krychowiak, M.; Lehnen, M.; Samm, U.; Unterberg, B.

    2008-01-01

    Beam emission spectroscopy on thermal helium is used at the TEXTOR tokamak as a reliable method to obtain radial profiles of electron temperature T-e(r, t) and electron density ne(r, t). In this paper the experimental realization of this method at TEXTOR and the status of the atomic physics employed

  1. A new apparatus for electron-ion multiple coincidence momentum imaging spectroscopy

    International Nuclear Information System (INIS)

    Morishita, Y.; Kato, M.; Pruemper, G.; Liu, X.-J.; Lischke, T.; Ueda, K.; Tamenori, Y.; Oura, M.; Yamaoka, H.; Suzuki, I.H.; Saito, N.

    2006-01-01

    We have developed a new experimental apparatus for the electron-ion multiple coincidence momentum imaging spectroscopy in order to obtain the angular distributions of vibration-resolved photoelectrons from molecules fixed in space. The apparatus consists of a four-stage molecular supersonic jet and a spectrometer analyzing three-dimensional momenta of fragment ions and electrons in coincidence

  2. The Electron-Phonon Interaction as Studied by Photoelectron Spectroscopy

    International Nuclear Information System (INIS)

    Lynch, D.W.

    2004-01-01

    With recent advances in energy and angle resolution, the effects of electron-phonon interactions are manifest in many valence-band photoelectron spectra (PES) for states near the Fermi level in metals

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

    International Nuclear Information System (INIS)

    Azevedo e Souza, A.C. de.

    1985-07-01

    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 -60 0 to + 60 0 ; 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 (C 2 H 6 , C 2 H 4 , C 2 H 2 ) have been obtained. The data were converted into double differential cross sections and generalized oscillator strenghts. (author) [pt

  4. Microanalysis by spectroscopy of transmitted electron energy losses

    International Nuclear Information System (INIS)

    Colliex, C.; Trebbia, P.

    1978-01-01

    Among the various signals which, in a transmission electron microscope, result from the interactions between the primary beam of well defined energy E 0 and the sample, the spectrum of the energy distribution of the electrons transmitted contains useful informations on the chemical and physical properties of the sample. Consequently the adaptation of an energy dispersive system on an electron microscope enables new fields of research to be investigated, particularly a localised chemical analysis technique with a space resolution scale equal to that of the electron microscope. It is this second aspect that we suggest describing in particular here. Already, this technique appears to be indispensable in the problems arising from the analysis of very small quantities of matter: detection limits in the order of 10 -19 to 10 -20 g (around 100 to 1000 atoms) would seem to be resonably possible [fr

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

    International Nuclear Information System (INIS)

    Southworth, S.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 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 H 2 and D 2 , and photoionization cross sections and photoelectron asymmetries of the valence orbitals of NO are reported

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-10-15

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

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

    International Nuclear Information System (INIS)

    Knut, Ronny; Lindblad, Rebecka; Gorgoi, Mihaela; Rensmo, Håkan; Karis, Olof

    2013-01-01

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

  8. Electron momentum density measurements by means of positron annihilation and Compton spectroscopy

    International Nuclear Information System (INIS)

    Gerber, W.; Dlubek, G.; Marx, U.; Bruemmer, O.; Prautzsch, J.

    1982-01-01

    The electron momentum density is measured applying positron annihilation and Compton spectroscopy in order to get information about electron wave functions. Compton spectroscopic measurements of Pd-Ag and Cu-Zn alloy systems are carried out taking into account crystal structure, mixability, and order state. Three-dimensional momentum densities of silicon are determined in order to get better information about its electronic structure. The momentum density and the spin density of ferromagnetic nickel are investigated using angular correlation curves

  9. 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.

  10. Electron temperature measurements in lowdensity plasmas by helium spectroscopy

    International Nuclear Information System (INIS)

    Brenning, N.

    1977-09-01

    This method to use relative intensities of singlet and triplet lines of neutral helium to measure electron temperature in low-density plasmas is examined. Calculations from measured and theoretical data about transitions in neutral helium are carried out and compared to experimental results. It is found that relative intensities of singlet and triplet lines from neutral helium only can be used for TE determination in low-density, short-duration plasmas. The most important limiting processes are excitation from the metastable 2 3 S level and excitation transfer in collisions between electrons and excited helium atoms. An evaluation method is suggested, which minimizes the effect of these processes. (author)

  11. Intramolecular dynamics due to electron transitions: from photoelectron spectroscopy to Femtochemistry

    International Nuclear Information System (INIS)

    Gadzuk, J.W.

    1999-01-01

    Select spectroscopic and chemical physics problems associated with atomic motion triggered by electronic transitions are the topics of this paper. The story starts with the initial stimulation provided by Dick Brundle's photoelectron spectroscopy studies of adsorbed molecules and continues to contemporary examples in photoelectron spectroscopy and Femtochemistry, all of which are theoretically modelled within a unified framework of time-dependent, driven oscillators and decaying states. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

  12. Stochastic stimulated electronic x-ray Raman spectroscopy

    Directory of Open Access Journals (Sweden)

    Victor Kimberg

    2016-05-01

    → π * transition. Our theoretical model describes the evolution of the spectral and temporal characteristics of the transmitted x-ray radiation, by solving the equation of motion for the electronic and vibrational degrees of freedom of the system self consistently with the propagation by Maxwell equations.

  13. 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 ...

  14. 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

  15. High Energy Electron Dosimetry by Alanine/ESR Spectroscopy

    International Nuclear Information System (INIS)

    Chu, Sung Sil

    1989-01-01

    Dosimetry based on electron spin resonance(ESR) analysis of radiation induced free radicals in amino acids is relevant to biological dosimetry applications. Alanine detectors are without walls and are tissue equivalent. Therefore, alanine ESR dosimetry looks promising for use in the therapy level. The dose range of the alanine/ESR dosimetry system can be extended down to l Gy. In a water phantom the absorbed dose of electrons generated by a medical linear accelerator of different initial energies (6-21 MeV) and therapeutic dose levels(1-60 Gy) was measured. Furthermore, depth dose measurements carried out with alanine dosimeters were compared with ionization chamber measurements. As the results, the measured absorbed doses for shallow depth of initial electron energies above 15 MeV were higher by 2-5% than those calculated by nominal energy CE factors. This seems to be caused by low energy scattered beams generated from the scattering foil and electron cones of beam projecting device in medical linear accelerator

  16. Electron beam imaging and spectroscopy of plasmonic nanoantenna resonances

    NARCIS (Netherlands)

    Vesseur, P.C.

    2011-01-01

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

  17. The Utilization of Spin Polarized Photoelectron Spectroscopy as a Probe of Electron Correlation with an Ultimate Goal of Pu

    International Nuclear Information System (INIS)

    Tobin, James; Yu, Sung; Chung, Brandon; Morton, Simon; Komesu, Takashi; Waddill, George

    2008-01-01

    We are developing the technique of spin-polarized photoelectron spectroscopy as a probe of electron correlation with the ultimate goal of resolving the Pu electronic structure controversy. Over the last several years, we have demonstrated the utility of spin polarized photoelectron spectroscopy for determining the fine details of the electronic structure in complex systems such as those shown in the paper.

  18. Coincident Auger electron and recoil ion momentum spectroscopy for low-energy ion-atom collisions

    Energy Technology Data Exchange (ETDEWEB)

    Laurent, G. E-mail: glaurent@ganil.fr; Tarisien, M.; Flechard, X.; Jardin, P.; Guillaume, L.; Sobocinski, P.; Adoui, L.; Bordenave-Montesquieu, A.; Bordenave-Montesquieu, D.; Chesnel, J.-Y.; Fremont, F.; Hennecart, D.; Lienard, E.; Maunoury, L.; Moretto-Capelle, P.; Cassimi, A

    2003-05-01

    The recoil ion momentum spectroscopy (RIMS) method combined with the detection of Auger electrons has been used successfully to analyse double electron capture following O{sup 6+} + He collisions at low impact velocities. Although RIMS and Auger spectroscopies are known to be efficient tools to obtain details on the primary processes occurring during the collision, the conjunction of both techniques provides new insights on the electron capture process. In the present experiment, triple coincidence detection of the scattered projectile, the target recoil ion and the Auger electron allows for a precise identification of the doubly excited states O{sup 4+} (1s{sup 2}nln{sup '}l{sup '}) populated after double electron-capture events.

  19. Two dimensional molecular electronics spectroscopy for molecular fingerprinting, DNA sequencing, and cancerous DNA recognition.

    Science.gov (United States)

    Rajan, Arunkumar Chitteth; Rezapour, Mohammad Reza; Yun, Jeonghun; Cho, Yeonchoo; Cho, Woo Jong; Min, Seung Kyu; Lee, Geunsik; Kim, Kwang S

    2014-02-25

    Laser-driven molecular spectroscopy of low spatial resolution is widely used, while electronic current-driven molecular spectroscopy of atomic scale resolution has been limited because currents provide only minimal information. However, electron transmission of a graphene nanoribbon on which a molecule is adsorbed shows molecular fingerprints of Fano resonances, i.e., characteristic features of frontier orbitals and conformations of physisorbed molecules. Utilizing these resonance profiles, here we demonstrate two-dimensional molecular electronics spectroscopy (2D MES). The differential conductance with respect to bias and gate voltages not only distinguishes different types of nucleobases for DNA sequencing but also recognizes methylated nucleobases which could be related to cancerous cell growth. This 2D MES could open an exciting field to recognize single molecule signatures at atomic resolution. The advantages of the 2D MES over the one-dimensional (1D) current analysis can be comparable to those of 2D NMR over 1D NMR analysis.

  20. Structural defects in multiferroic BiMnO3 studied by transmission electron microscopy and electron energy-loss spectroscopy

    International Nuclear Information System (INIS)

    Yang, H.; Chi, Z. H.; Yao, L. D.; Zhang, W.; Li, F. Y.; Jin, C. Q.; Yu, R. C.

    2006-01-01

    The multiferroic material BiMnO 3 synthesized under high pressure has been systematically studied by transmission electron microscopy and electron energy-loss spectroscopy, and some important structural defects are revealed in this multiferroic material. The frequently observed defects are characterized to be Σ3(111) twin boundaries, Ruddlesden-Popper [Acta Crystallogr. 11, 54 (1958)] antiphase boundaries, and a p p superdislocations connected with a small segment of Ruddlesden-Popper defect. These defects are present initially in the as-synthesized sample. In addition, we find that ordered voids (oxygen vacancies) are easily introduced into the multiferroic BiMnO 3 by electron-beam irradiation

  1. High-dose dosimetry using electron spin resonance (ESR) spectroscopy

    International Nuclear Information System (INIS)

    Kojima, Takuji; Tanaka, Ryuichi

    1992-01-01

    An electron spin resonance (ESR) dosimeter capable of measuring large doses of radiation in radiotherapy and radiation processing is outlined. In particular, an alanine/ESR dosimeter is discussed, focusing on the development of elements, the development of the ESR dosimetric system, the application of alanine/ESR dosimeter, and basic researches. Rod elements for gamma radiation and x radiation and film elements for electron beams are described in detail. The following recent applications of the alanine/ESR dosimeter are introduced: using as a transfer dosimeter, applying to various types of radiation, diagnosing the deterioration of radiological materials and equipments, and applying to ESR imaging. The future subjects to be solved in the alanine/ESR dosimetric system are referred to as follows: (1) improvement of highly accurate elements suitable for the measurement of various types of radiation, (2) establishment of sensitive calibration method of the ESR equipment itself, and (3) calibration and standardization of radiation doses. (K.N.) 65 refs

  2. Electron energy-loss spectroscopy of branched gap plasmon resonators

    DEFF Research Database (Denmark)

    Raza, Søren; Esfandyarpour, Majid; Koh, Ai Leen

    2016-01-01

    The miniaturization of integrated optical circuits below the diffraction limit for high-speed manipulation of information is one of the cornerstones in plasmonics research. By coupling to surface plasmons supported on nanostructured metallic surfaces, light can be confined to the nanoscale......, enabling the potential interface to electronic circuits. In particular, gap surface plasmons propagating in an air gap sandwiched between metal layers have shown extraordinary mode confinement with significant propagation length. In this work, we unveil the optical properties of gap surface plasmons...... in silver nanoslot structures with widths of only 25 nm. We fabricate linear, branched and cross-shaped nanoslot waveguide components, which all support resonances due to interference of counter-propagating gap plasmons. By exploiting the superior spatial resolution of a scanning transmission electron...

  3. Study of the electronic structure of pure aluminium, aluminium oxide and nitride by spectroscopy of electrons excited under electronic and photonic bombardment (X and UV)

    International Nuclear Information System (INIS)

    Gautier-Soyer, Martine

    1985-01-01

    This research thesis reports the use of electron spectroscopy with electrons excited under electronic or photonic (X or UV) bombardment for the study of electronic state density of aluminium, aluminium oxide (Al 2 O 3 ) and aluminium nitride (AlN). The objective is to get an insight into phenomena related to technological problems of adherence, wear, lubrication, corrosion or breakdown met in metals, insulators and semiconductors. The author highlighted the presence of occupied surface states on Al(111) and Al(100), and electronic levels localised in the forbidden band of Al 2 O 3 and AlN, induced by structural defects which promote surface reactivity [fr

  4. Auger electron spectroscopy study on interaction between aluminum thin layers and uranium substrate

    International Nuclear Information System (INIS)

    Zhou Wei; Liu Kezhao; Yang Jiangrong; Xiao Hong; Jiang Chunli; Lu Lei

    2005-01-01

    Aluminum thin layers on uranium were prepared by sputter deposition at room temperature in ultra high vacuum analysis chamber. Interaction between U and Al, and growth mode were investigated by Auger electron spectroscopy (AES) and electron energy loss spectroscopy (EELS). It is shown that Al thin film growth follows the volmer-weber (VW) mode. At room temperature, Al and U interact with each other, resulting in interdiffusion action and formation of U-Al alloys at U/Al interface. Annealing promotes interaction and interdiffusion between U and Al, and UAl x maybe formed at interface. (authors)

  5. Morphology, surface roughness, electron inelastic and quasi-elastic scattering in elastic peak electron spectroscopy of polymers

    International Nuclear Information System (INIS)

    Lesiak, B.; Kosinski, A.; Nowakowski, R.; Koever, L.; Toth, J.; Varga, D.; Cserny, I.; Sulyok, A.; Gergely, G.

    2006-01-01

    Complete text of publication follows. Elastic peak electron spectroscopy (EPES) deals with the interaction of electrons with atoms of a solid surface, studying the distribution of electrons backscattered elastically. The nearest vicinity of the elastic peak, (low kinetic energy region) reflects both, electron inelastic and quasi-elastic processes. The incident electrons produce surface excitations, inducing surface plasmons with the corresponding loss peaks separated by 1 - 20 eV energy from the elastic peak. Quasi-elastic losses result from the recoil of scattering atoms of different atomic number, Z. The respective energy shift and Doppler broadening of the elastic peak depend on Z, the primary electron energy, E, and the measurement geometry. Quantitative surface analytical application of EPES, such as determination of parameters describing electron transport, requires a comparison of experimental data with corresponding data derived from Monte Carlo (MC) simulation. Several problems occur in EPES studies of polymers. The intensity of elastic peak, considered in quantitative surface analysis, is influenced by both, the inelastic and quasi-elastic scattering processes (especially for hydrogen scattering atoms and primary electron energy above 1000 eV). An additional factor affecting the elastic peak intensity is the surface morphology and roughness. The present work compares the effect of these factors on the elastic peak intensity for selected polymers (polyethylene, polyaniline and polythiophenes). X-ray photoelectron spectroscopy (XPS) and helium pycnometry are applied for deriving the surface atomic composition and the bulk density, while scanning electron microscopy (SEM) and atomic force microscopy (AFM) for determining surface morphology and roughness. According to presented results, the influence of surface morphology and roughness is larger than those of surface excitations or recoil of hydrogen atoms. The component due to recoil of hydrogen atoms can be

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2000-01-01

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

  7. Imaging photoelectron photoion coincidence spectroscopy with velocity focusing electron optics

    International Nuclear Information System (INIS)

    Bodi, Andras; Johnson, Melanie; Gerber, Thomas; Gengeliczki, Zsolt; Sztaray, Balint; Baer, Tomas

    2009-01-01

    An imaging photoelectron photoion coincidence spectrometer at the vacuum ultraviolet (VUV) beamline of the Swiss Light Source is presented and a few initial measurements are reported. Monochromatic synchrotron VUV radiation ionizes the cooled or thermal gas-phase sample. Photoelectrons are velocity focused, with better than 1 meV resolution for threshold electrons, and also act as start signal for the ion time-of-flight analysis. The ions are accelerated in a relatively low, 40-80 V cm -1 field, which enables the direct measurement of rate constants in the 10 3 -10 7 s -1 range. All electron and ion events are recorded in a triggerless multiple-start/multiple-stop setup, which makes it possible to carry out coincidence experiments at >100 kHz event frequencies. As examples, the threshold photoelectron spectrum of the argon dimer and the breakdown diagrams for hydrogen atom loss in room temperature methane and the chlorine atom loss in cold chlorobenzene are shown and discussed.

  8. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Li, Meng; Xu, Chunkai, E-mail: xuck@ustc.edu.cn, E-mail: xjun@ustc.edu.cn; Zhang, Panke; Li, Zhean; Chen, Xiangjun, E-mail: xuck@ustc.edu.cn, E-mail: xjun@ustc.edu.cn [Hefei National Laboratory for Physical Science at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei 230026 (China)

    2016-08-15

    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.

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

    International Nuclear Information System (INIS)

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

    2016-01-01

    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.

  11. 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.

  12. Electronic structure of Sr2RuO4 studied by angle-resolved photoemission spectroscopy

    International Nuclear Information System (INIS)

    Iwasawa, H.; Aiura, Y.; Saitoh, T.; Yoshida, Y.; Hase, I.; Ikeda, S.I.; Bando, H.; Kubota, M.; Ono, K.

    2007-01-01

    Electronic structure of the monolayer strontium ruthenate Sr 2 RuO 4 was investigated by high-resolution angle-resolved photoemission spectroscopy. We present photon-energy (hν) dependence of the electronic structure near the Fermi level along the ΓM line. The hν dependence has shown a strong spectral weight modulation of the Ru 4d xy and 4d zx bands

  13. Application of positron annihilation induced auger electron spectroscopy to the study of surface chemistry

    International Nuclear Information System (INIS)

    Weiss, A.H.; Yang, G.; Nangia, A.; Kim, J.H.; Fazleev, N.G.

    1996-01-01

    Positron annihilation induced Auger Electron Spectroscopy (PAES), makes use a beam of low energy positrons to excite Auger transitions by annihilating core electrons. This novel mechanism provides PAES with a number of unique features which distinguishes it from other methods of surface analysis. In PAES the very large collisionally induced secondary electron background which is present under the low energy Auger peaks using conventional techniques can be eliminated by using a positron beam whose energy is below the range of Auger electron energies. In addition, PAES is more surface selective than conventional Auger Spectroscopy because the PAES signal originates almost exclusively from the topmost atomic layer due to the fact that the positrons annihilating with the core electrons are trapped in an image correlation well just outside the surface. In this paper, recent applications of Positron Annihilation Induced Auger Electron Spectroscopy (PAES) to the study of surface structure and surface chemistry will be discussed including studies of the growth, alloying and inter-diffusion of ultrathin layers of metals, metals on semiconductors, and semiconductors on semiconductors. In addition, the possibilities for future application of PAES to the study of catalysis and surface chemistry will be outlined. (author)

  14. 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.

  15. Application of ESCA spectroscopy to the study of electronic structure of high temperature superconductors

    International Nuclear Information System (INIS)

    Dagoury, G.

    1988-01-01

    Characteristics of high T c oxide superconductors are very sensitive to slight variation of chemical composition, ESCA spectroscopy is used for identification of YBaCuO superconductivity. Binding energy of the different electronic levels and structure of valence band are determined [fr

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

    NARCIS (Netherlands)

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

    2015-01-01

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

  17. Identifying highly conducting Au–C links through inelastic electron tunneling spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Foti, G.; Vázquez, Héctor; Sanchez-Portal, D.; Arnau, A.; Frederiksen, T.

    2014-01-01

    Roč. 118, OCT (2014), s. 27106-27112 ISSN 1932-7447 Institutional support: RVO:68378271 Keywords : molecular electronics * alkanes * tin-functionalization * anchoring groups * vibrational spectroscopy Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.772, year: 2014

  18. Auger-electron spectroscopy investigation of thin Ag-As-S-Se films

    International Nuclear Information System (INIS)

    Todorov, R; Spasov, G; Petkov, K; Tasseva, J

    2010-01-01

    The photoinduced changes in the refractive index and optical band-gap of thin As 32 S 34 Se 34 films photodoped with silver were studied using spectrophotometric methods. The compositional profile of the films was revealed by means of Auger-electron spectroscopy.

  19. Auger-electron spectroscopy investigation of thin Ag-As-S-Se films

    Energy Technology Data Exchange (ETDEWEB)

    Todorov, R; Spasov, G; Petkov, K; Tasseva, J, E-mail: jordanka@clf.bas.b [Acad. J. Malinowski Central Laboratory of Photoprocesses, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 109, 1113 Sofia (Bulgaria)

    2010-04-01

    The photoinduced changes in the refractive index and optical band-gap of thin As{sub 32}S{sub 34}Se{sub 34} films photodoped with silver were studied using spectrophotometric methods. The compositional profile of the films was revealed by means of Auger-electron spectroscopy.

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

    DEFF Research Database (Denmark)

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

    2017-01-01

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

  1. 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

    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...

  2. The Generalized Multipole Technique for the Simulation of Low-Loss Electron Energy Loss Spectroscopy

    DEFF Research Database (Denmark)

    Kiewidt, Lars; Karamehmedovic, Mirza

    2018-01-01

    In this study, we demonstrate the use of a Generalized Multipole Technique (GMT) to simulate low-loss Electron Energy Loss Spectroscopy (EELS) spectra of isolated spheriodal nanoparticles. The GMT provides certain properties, such as semi-analytical description of the electromagnetic fields...

  3. Effective attenuation lengths for quantitative determination of surface composition by Auger-electron spectroscopy and X-ray photoelectron spectroscopy

    International Nuclear Information System (INIS)

    Jablonski, A.; Powell, C.J.

    2017-01-01

    Highlights: • Effective attenuation lengths (EALs) for determination of surface composition by XPS. • Considerable difference from EALs used for overlayer thickness measurements. • New analytical algorithms for calculating the effective attenuation length. - Abstract: The effective attenuation length (EAL) is normally used in place of the inelastic mean free path (IMFP) to account for elastic-scattering effects when describing the attenuation of Auger electrons and photoelectrons from a planar substrate by an overlayer film. An EAL for quantitative determination of surface composition by Auger-electron spectroscopy (AES) or X-ray photoelectron spectroscopy (XPS) is similarly useful to account for elastic-scattering effects on the signal intensities. We calculated these EALs for four elemental solids (Si, Cu, Ag, and Au) and for energies between 160 eV and 1.4 keV. The XPS calculations were made for two instrumental configurations while the AES calculations were made from the XPS formalism after “switching off” the XPS anisotropy. The EALs for quantitative determination of surface composition by AES and XPS were weak functions of emission angle for emission angles between 0 and 50°. The ratios of the average values of these EALs to the corresponding IMFPs could be fitted to a second-order function of the single-scattering albedo, a convenient measure of the strength of elastic-scattering effects. EALs for quantitative determination of surface composition by AES and XPS for other materials can be simply found from this relationship.

  4. Photon- and electron-induced surface voltage in electron spectroscopies on ZnSe(0 0 1)

    International Nuclear Information System (INIS)

    Cantoni, M.; Bertacco, R.; Brambilla, A.; Ciccacci, F.

    2009-01-01

    The surface band bending in ZnSe(0 0 1), as a function of the temperature, is investigated both in the valence band (by photoemission) and in the conduction band (by inverse photoemission and absorbed current spectroscopies). Two different mechanisms are invoked for interpreting the experimental data: the band bending due to surface states, and the surface voltage induced by the incident beam. While the latter is well known in photoemission (surface photovoltage), we demonstrate the existence of a similar effect in inverse photoemission and absorbed current spectroscopies, induced by the incident electrons instead of photons. These results point to the importance of considering the surface voltage effect even in electron-in techniques for a correct evaluation of the band bending.

  5. Interpretation of intensities in electron-momentum and photoelectron spectroscopies

    International Nuclear Information System (INIS)

    McCarthy, I.E.

    1984-06-01

    Relative intensities for the photoelectron reaction on atoms and molecules are not related to structure calculations in the same way as those for the noncoplanar symmetric (e,2e) reaction. The photoelectron dipole matrix element is dependent on recoil momentum only through its unique relationship to the photon energy and is much harder to calculate for chemically-interesting momenta. Relative intensities for binary (e,2e) reactions are independent of total energy at high enough energies and strongly dependent on symmetry and recoil momentum, for which an intensity profile can be measured for values starting at zero. In comparing with structure calculations, binary (e,2e) intensities for low recoil momentum may be compared directly with pole strengths in calculations of the one-electron Green's function or corresponding configuration-interaction calculations. In the case of states within a single symmetry manifold the relative intensities will be independent of recoil momentum up to some maximum, usually at least a few atomic units

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

    International Nuclear Information System (INIS)

    Hillenbrand, Pierre-Michel

    2013-07-01

    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 U 88+ + N 2 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 U 28+ with different gases were measured.

  7. A study of core electron binding energies in technetium-99m complexes by internal conversion electron spectroscopy

    International Nuclear Information System (INIS)

    Burke, J.F.; Archer, C.M.; Wei Chiu, K.; Latham, I.A.; Egdell, R.G.

    1991-01-01

    Core electron binding energies in a series of 99m Tc complexes have been studied by internal conversion electron spectroscopy (ICES) in a conventional x-ray photoelectron spectrometer. In both 3d and 3p regions, a chemical shift of about 1 eV is observed per unit increase in oxidation state. The role of ICES in characterizing radiopharmaceutical agents is illustrated with studies of some novel 99m Tc-phosphine complexes that have been developed for myocardial perfusion imaging. (author)

  8. Quantifying electronic band interactions in van der Waals materials using angle-resolved reflected-electron spectroscopy.

    Science.gov (United States)

    Jobst, Johannes; van der Torren, Alexander J H; Krasovskii, Eugene E; Balgley, Jesse; Dean, Cory R; Tromp, Rudolf M; van der Molen, Sense Jan

    2016-11-29

    High electron mobility is one of graphene's key properties, exploited for applications and fundamental research alike. Highest mobility values are found in heterostructures of graphene and hexagonal boron nitride, which consequently are widely used. However, surprisingly little is known about the interaction between the electronic states of these layered systems. Rather pragmatically, it is assumed that these do not couple significantly. Here we study the unoccupied band structure of graphite, boron nitride and their heterostructures using angle-resolved reflected-electron spectroscopy. We demonstrate that graphene and boron nitride bands do not interact over a wide energy range, despite their very similar dispersions. The method we use can be generally applied to study interactions in van der Waals systems, that is, artificial stacks of layered materials. With this we can quantitatively understand the 'chemistry of layers' by which novel materials are created via electronic coupling between the layers they are composed of.

  9. Radiosterilization dosimetry by electron-spin resonance spectroscopy. Cefotetan

    International Nuclear Information System (INIS)

    Basly, J.P.; Longy, I.; Bernard, M.

    1998-01-01

    As an alternative to heat and gas exposure sterilization, ionizing radiation is gaining interest as a sterilization process for medicinal products. Nevertheless, essentially for economic profit, unauthorized and uncontrolled use of radiation processes may be expected. In this context, it is necessary to find methods of distinguishing between irradiated and nonirradiated pharmaceuticals. In the absence of suitable detection methods, our attention was focused on electron-spin resonance (ESR) spectrometry. A third generation cephalosporin, cefotetan, was chosen as a model; this antibiotic is a potential candidate for radiation treatment due to its thermosensitivity. While the ESR spectra of a nonirradiated sample presents no signal, a nonsymmetrical signal, dependent on the irradiation dose, is found in irradiated samples. The number of free radicals was estimated by comparing the second integral from radiosterilized samples and a diphenylpicryl hydrazyl reference. Estimation of the number of free radicals gives 7x10 17 radicals g -1 at 20kGy (1.1x10 16 radicals in 15mg). From this result, the G-value (number of radicals (100eV) -1 ) could be estimated as 0.6. Decay of radicals upon storage were modeled using a bi-exponential function. The limit of detection of free radicals after irradiation at 25kGy is up to two years. This result agrees with those obtained on other cephalosporins. Aside from qualitative detection, ESR spectrometry can be used for dose estimation. Linear regression is applicable for doses lower than 20kGy. Since the radiation dose selected must always be based upon the bioburden of the products and the degree of sterility required (EN 552 and ANSI/AAMI/ISO 11137), 25kGy could no longer be accepted as a 'routine' dose for sterilizing a pharmaceutical. Doses in the 5-20kGy range could be investigated and linear regression appeared to be the least expensive route to follow. The best results for the integration of the curves were obtained with

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

    International Nuclear Information System (INIS)

    Yang Wanli; Qiao Ruimin

    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. (topical review)

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

    KAUST Repository

    Lopatin, Sergei; Cheng, Bin; Liu, Wei-Ting; Tsai, Meng-Lin; He, Jr-Hau; Chuvilin, Andrey

    2017-01-01

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

  12. Energy-momentum density of graphite by electron-momentum spectroscopy

    International Nuclear Information System (INIS)

    Vos, M.; Fang, Z.; Canney, S.; Kheifets, A.; McCarthy, I.E.; Weigold, E.

    1996-11-01

    The energy-resolved electron momentum density of graphite has been measured along a series of well-defined directions using electron momentum spectroscopy (EMS). This is the first measurement of this kind performed on a single-crystal target with a thoroughly controlled orientation which clearly demonstrates the different nature of the σ and π bands in graphite. Good agreement between the calculated density and the measured one is found, further establishing that fact that EMS yields more direct and complete information on the valence electronic structure that any other method. 12 refs., 2 figs

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

    International Nuclear Information System (INIS)

    Atzkern, S.

    2001-01-01

    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 Li 2 CuO 2 , CuGeO 3 , V 2 O 5 and α'-NaVO 5 . 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

  14. Dispersive electron transport in tris(8-hydroxyquinoline) aluminum (Alq3) probed by impedance spectroscopy.

    Science.gov (United States)

    Berleb, Stefan; Brütting, Wolfgang

    2002-12-31

    Electron transport in tris(8-hydroxyquinoline) aluminum (Alq3) is investigated by impedance spectroscopy under conditions of space-charge limited conduction (SCLC). Existing SCLC models are extended to include the field dependence of the charge carrier mobility and energetically distributed trap states. The dispersive nature of electron transport is revealed by a frequency-dependent mobility with a dispersion parameter alpha in the range 0.4-0.5, independent of temperature. This indicates that positional rather than energetic disorder is the dominant mechanism for the dispersive transport of electrons in Alq3.

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

    Science.gov (United States)

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

    2017-07-01

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

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

    KAUST Repository

    Lopatin, Sergei

    2017-09-01

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

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

    International Nuclear Information System (INIS)

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

    2011-01-01

    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

  18. 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

  19. Surface analysis of Al alloys with X-ray photoelectron and Auger electron spectroscopies

    International Nuclear Information System (INIS)

    Sakairi, Masatoshi; Suzuki, Keita; Sasaki, Ryo

    2015-01-01

    In this paper, X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES) were applied to investigate passive films formed on aluminum alloy in 0.5 kmol m -3 H 3 BO 3 /0.05 kmol m -3 Na 2 B 4 O 7 with different metal cations. The metal cation is classified by metal cation hardness, X, which are calculated based on the concept of hard and soft acids and bases (HSAB) of the acid and base in Lewis's rule. From XPS analysis, the metal cations with X > 4 were incorporated in passive films. The area-selected surface analysis of AES was also introduced. (author)

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

    International Nuclear Information System (INIS)

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

    2016-01-01

    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. (paper)

  1. Study of distribution of electron density in heteropolymolybdates by method of X-ray electron spectroscopy

    International Nuclear Information System (INIS)

    Molchanov, V.N.; Kazanskij, L.P.; Torchenkova, E.A.; Spitsyn, V.I.

    1978-01-01

    X-ray electron spectra of some iso- and heteropolymolybdates relating to different structure types are investigated to study electron structure of complex polyoxyion-heteropolyanions. Binding energies of Modsub(5/2) and 01s-electrons in iso- and heteropolycompounds line are measured and their interdependence is detected. The effective charge of oxygen and molybdenum atoms in heteropolymolybdates increases with decreasing a number of external sphere cations per an oxygen atom and a number of Mo=0 multiple bonds

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

    Science.gov (United States)

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

    2016-03-10

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

  3. Isotope effect on hydrated electron relaxation dynamics studied with time-resolved liquid jet photoelectron spectroscopy

    Science.gov (United States)

    Elkins, Madeline H.; Williams, Holly L.; Neumark, Daniel M.

    2016-05-01

    The excited state relaxation dynamics of the solvated electron in H2O and D2O are investigated using time-resolved photoelectron spectroscopy in a liquid microjet. The data show that the initial excited state decays on a time scale of 75 ± 12 fs in H2O and 102 ± 8 fs in D2O, followed by slower relaxation on time scales of 400 ± 70 fs and 390 ± 70 fs that are isotopically invariant within the precision of our measurements. Based on the time evolution of the transient signals, the faster and slower time constants are assigned to p → s internal conversion (IC) of the hydrated electron and relaxation on the ground electronic state, respectively. This assignment is consistent with the non-adiabatic mechanism for relaxation of the hydrated electron and yields an isotope effect of 1.4 ± 0.2 for IC of the hydrated electron.

  4. Development of Micron-Resolved Electron Spectroscopy to Study Organic Thin Films in Real Devices

    International Nuclear Information System (INIS)

    Wang, C.-H.; Fan, L.-J.; Yang, Y.-W.; Su, J.-W.; Chan, S.-W.; Chen, M.-C.

    2010-01-01

    A straightforward application of an electron energy analyzer equipped with an image detector to micron-resolved electron spectroscopic studies of organic thin film devices is reported. The electron spectroscopies implemented include synchrotron-based UPS, XPS, and Auger yield NEXAFS. Along the non-energy-dispersion direction of the analyzer, a spatial resolution of ∼40 μm is obtained through the employment of entrance slits, electrostatic lenses and segmented CCD detector. One significant benefit offered by the technique is that the electronic transport and electronic structure of the same micron-sized sample can be directly examined. The example illustrated is a top-contact organic field effect transistor (OFET) fabricated from semiconducting triethylsilylethynyl anthradithiophene and gold electrodes. It is found that an extensive out-diffusion of gold atoms to adjacent conduction channels takes place, presumably due to the inability of soft organic materials in dissipating the excess energy with which gaseous Au atoms possess.

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

    International Nuclear Information System (INIS)

    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

  6. 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.

  7. Key electronic states in lithium battery materials probed by soft X-ray spectroscopy

    International Nuclear Information System (INIS)

    Yang, Wanli; Liu, Xiaosong; Qiao, Ruimin; Olalde-Velasco, Paul; Spear, Jonathan D.; Roseguo, Louis; Pepper, John X.; Chuang, Yi-de; Denlinger, Jonathan D.; Hussain, Zahid

    2013-01-01

    Highlights: •Key electronic states in battery materials revealed by soft X-ray spectroscopy. •Soft X-ray absorption consistently probes Mn oxidation states in different systems. •Soft X-ray absorption and emission fingerprint battery operations in LiFePO 4 . •Spectroscopic guidelines for selecting/optimizing polymer materials for batteries. •Distinct SEI formation on same electrode material with different crystal orientations. -- Abstract: The formidable challenges for developing a safe, low-cost, high-capacity, and high-power battery necessitate employing advanced tools that are capable of directly probing the key electronic states relevant to battery performance. Synchrotron based soft X-ray spectroscopy directly measures both the occupied and unoccupied states in the vicinity of the Fermi level, including transition-metal-3d and anion-p states. This article presents the basic concepts on how fundamental physics in electronic structure could provide valuable information for lithium-ion battery applications. We then discuss some of our recent studies on transition-metal oxide based cathodes, silicon based anode, and solid-electrolyte-interphase through soft X-ray absorption and emission spectroscopy. We argue that spectroscopic results reveal the evolution of electronic states for fingerprinting, understanding, and optimizing lithium-ion battery operations

  8. Contributions to the theory of electron spectroscopy. Applications of the relativistic multiple-scattering theory

    International Nuclear Information System (INIS)

    Henk, J.

    2004-01-01

    Electron spectroscopy provides access to fundamental properties of solids, such as the geometric, electronic, and the magnetic structure. The latter are necessary for the understanding of a variety of basic but nevertheless important effects. The present work outlines recently developed theoretical approaches to electron spectroscopies. Most of the collected results rely on first-principles calculations, as formulated in multiple-scattering theory, and are contrasted with experimental findings. One topic involves spin- and angle-resolved photoelectron spectroscopy which is addressed for magnetic surfaces and ultrathin films. Exemplary results comprise magnetic dichroism in both valence-band and core-level photoemission as well as the temperature dependence of magnetic properties of ultrathin films. Another topic is spin-dependent ballistic transport through planar tunnel junctions, focusing here on the zero-bias anomaly. In most of the cases, spin-orbit coupling (SOC) is an essential ingredient and, hence, favors a relativistic description. Prominent effects of SOC are illustrated by means of the electronic structure of rare gases adsorbed on a substrate and by the splitting of surface states on Au(111). Concerning magnetism, the magnetic anisotropy of Ni films on Cu(001) is discussed, focusing in particular on the spin reorientation transition induced by lattice distortions in ultrathin films. (orig.)

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

    Science.gov (United States)

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

    2017-07-01

    Surface and near-surface electronic states were probed with nanometer spatial resolution in MgO and TiO 2 anatase nanoparticles using ultra-high energy resolution electron energy-loss spectroscopy (EELS) coupled to a scanning transmission electron microscope (STEM). This combination allows the surface electronic structure determined with spectroscopy to be correlated with nanoparticle size, morphology, facet etc. By acquiring the spectra in aloof beam mode, radiation damage to the surface can be significantly reduced while maintaining the nanometer spatial resolution. MgO and TiO 2 showed very different bandgap features associated with the surface/sub-surface layer of the nanoparticles. Spectral simulations based on dielectric theory and density of states models showed that a plateau feature found in the pre-bandgap region in the spectra from (100) surfaces of 60nm MgO nanocubes is consistent with a thin hydroxide surface layer. The spectroscopy shows that this hydroxide species gives rise to a broad filled surface state at 1.1eV above the MgO valence band. At the surfaces of TiO 2 nanoparticles, pronounced peaks were observed in the bandgap region, which could not be well fitted to defect states. In this case, the high refractive index and large particle size may make Cherenkov or guided light modes the likely causes of the peaks. Copyright © 2016 Elsevier B.V. All rights reserved.

  10. Investigation of electron momentum distributions for outer valence orbitals of trichlorofluoromethane by (e, 2e) electron momentum spectroscopy

    International Nuclear Information System (INIS)

    Zhou, L.X.; Shan, X.; Chen, X.J.; Yin, X.F.; Zhang, X.H.; Xu, C.K.; Wei, Z.; Xu, K.Z.

    2006-01-01

    The binding energy spectra and electron momentum distributions for the outer valence orbitals of trichlorofluoromethane (CFCl 3 ) have been measured by binary (e, 2e) electron momentum spectroscopy (EMS) at an impact energy of 1200 eV + binding energy. The experimental electron momentum profiles are compared with Hartree-Fock and density functional theory (DFT) calculations with different-sized basis sets. Generally, the DFT calculations employing B3LYP functional with large basis sets of AUG-cc-pVDZ and AUG-cc-pVTZ give better description of the experimental results. But for 3e orbital, all the theoretical calculations underestimate the experiment, which is probably due to the distorted-wave effect that often occurs in π*-like molecular orbital

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

    International Nuclear Information System (INIS)

    Kimman, J.T.N.

    1984-01-01

    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.)

  12. Study of electron transmission through thin metallic films by the electron moessbauer spectroscopy

    International Nuclear Information System (INIS)

    Babikova, Yu.F.; Vakar, O.M.; Gruzin, O.M.; Petrikin, Yu.V.

    1983-01-01

    Results of the experimental study of the transmission of conversion electrons through aluminium, iron, tin and gold films are presented. Absorption of resonance electrons of the Moessbauer nuclide 57 Fe, formed during target irradiation with γ-quanta of 57 Co source in chromium matrix has been studied. It is asserted that absorption of conversion electrons in films of different elements is similar; at that, like in the case of β-particles, the law of absorption of resonance electrons, emitted from the flat layer, is exponential For conversion electrons of the Moessbauer nuclide 57 Fe the absorption coefficient is (0.025+-0.002) cm 2 /μg, which in the case of iron absorbing film corresponds to (20.0+-1.0)x10 4 cm -1

  13. High-Frequency Electron Paramagnetic Resonance Spectroscopy of Nitroxide-Functionalized Nanodiamonds in Aqueous Solution.

    Science.gov (United States)

    Akiel, R D; Stepanov, V; Takahashi, S

    2017-06-01

    Nanodiamond (ND) is an attractive class of nanomaterial for fluorescent labeling, magnetic sensing of biological molecules, and targeted drug delivery. Many of those applications require tethering of target biological molecules on the ND surface. Even though many approaches have been developed to attach macromolecules to the ND surface, it remains challenging to characterize dynamics of tethered molecule. Here, we show high-frequency electron paramagnetic resonance (HF EPR) spectroscopy of nitroxide-functionalized NDs. Nitroxide radical is a commonly used spin label to investigate dynamics of biological molecules. In the investigation, we developed a sample holder to overcome water absorption of HF microwave. Then, we demonstrated HF EPR spectroscopy of nitroxide-functionalized NDs in aqueous solution and showed clear spectral distinction of ND and nitroxide EPR signals. Moreover, through EPR spectral analysis, we investigate dynamics of nitroxide radicals on the ND surface. The demonstration sheds light on the use of HF EPR spectroscopy to investigate biological molecule-functionalized nanoparticles.

  14. Electron stimulated carbon adsorption in ultra high vacuum monitored by Auger Electron Spectroscopy (AES)

    CERN Document Server

    Scheuerlein, C

    2001-01-01

    Electron stimulated carbon adsorption at room temperature (RT) has been studied in the context of radiation induced surface modifications in the vacuum system of particle accelerators. The stimulated carbon adsorption was monitored by AES during continuous irradiation by 2.5 keV electrons and simultaneous exposure of the sample surface to CO, CO2 or CH4. The amount of adsorbed carbon was estimated by measuring the carbon Auger peak intensity as a function of the electron irradiation time. Investigated substrate materials are technical OFE copper and TiZrV non-evaporable getter (NEG) thin film coatings, which are saturated either in air or by CO exposure inside the Auger electron spectrometer. On the copper substrate electron induced carbon adsorption from gas phase CO and CO2 is below the detection limit of AES. During electron irradiation of the non-activated TiZrV getter thin films, electron stimulated carbon adsorption from gas phase molecules is detected when either CO or CO2 is injected, whereas the CH4 ...

  15. 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.)

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

    International Nuclear Information System (INIS)

    Lestinsky, M.

    2007-01-01

    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 18+ yield a high-precision measurement of the 2s-2p 3/2 transition energy in this system. Operation of the two-electron-beam setup at high collision energy (∼1000 eV) is established using resonances of hydrogenlike Mg 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 6+ . (orig.)

  17. Reflections on hard X-ray photon-in/photon-out spectroscopy for electronic structure studies

    Energy Technology Data Exchange (ETDEWEB)

    Glatzel, Pieter, E-mail: glatzel@esrf.fr [European Synchrotron Radiation Facility, 6 Rue Jules Horowitz, 38043 Grenoble (France); Weng, Tsu-Chien; Kvashnina, Kristina; Swarbrick, Janine; Sikora, Marcin [European Synchrotron Radiation Facility, 6 Rue Jules Horowitz, 38043 Grenoble (France); Gallo, Erik [European Synchrotron Radiation Facility, 6 Rue Jules Horowitz, 38043 Grenoble (France); Department of Inorganic, Physical and Materials Chemistry, INSTM Reference Center and NIS Centre of Excellence, Università di Torino, Via P. Giuria 7, I-10125 Torino (Italy); Smolentsev, Nikolay [European Synchrotron Radiation Facility, 6 Rue Jules Horowitz, 38043 Grenoble (France); Research Center for Nanoscale Structure of Matter, Southern Federal University, str. Zorge 5, 344090 Rostov-on-Don (Russian Federation); Mori, Roberto Alonso [European Synchrotron Radiation Facility, 6 Rue Jules Horowitz, 38043 Grenoble (France)

    2013-06-15

    Highlights: ► Overview of some recent developments in hard X-ray RXES/RIXS. ► Evaluation of spectral line broadening in RXES/RIXS. ► Modelling of RXES/RIXS by ground state DFT calculations. ► Discussion on when HERFD provides a good approximation to XAS. -- Abstract: An increasing community of researchers in various fields of natural sciences is combining X-ray absorption with X-ray emission spectroscopy (XAS–XES) to study electronic structure. With the applications becoming more diverse, the objectives and the requirements in photon-in/photon-out spectroscopy are becoming broader. It is desirable to find simple experimental protocols, robust data reduction and theoretical tools that help the experimentalist to understand their data and learn about the electronic structure. This article presents a collection of considerations on non-resonant and resonant XES with the aim to guide the experimentalist to make good use of this technique.

  18. Spin noise spectroscopy of donor-bound electrons in ZnO

    Science.gov (United States)

    Horn, H.; Balocchi, A.; Marie, X.; Bakin, A.; Waag, A.; Oestreich, M.; Hübner, J.

    2013-01-01

    We investigate the intrinsic spin dynamics of electrons bound to Al impurities in bulk ZnO by optical spin noise spectroscopy. Spin noise spectroscopy enables us to investigate the longitudinal and transverse spin relaxation time with respect to nuclear and external magnetic fields in a single spectrum. On one hand, the spin dynamic is dominated by the intrinsic hyperfine interaction with the nuclear spins of the naturally occurring 67Zn isotope. We measure a typical spin dephasing time of 23 ns, in agreement with the expected theoretical values. On the other hand, we measure a third, very high spin dephasing rate which is attributed to a high defect density of the investigated ZnO material. Measurements of the spin dynamics under the influence of transverse as well as longitudinal external magnetic fields unambiguously reveal the intriguing connections of the electron spin with its nuclear and structural environment.

  19. 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

    2015-07-31

    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.

  20. Electronic structure of molecules of substituted benzenes by x-ray spectroscopy. I. Nitrobenzene

    International Nuclear Information System (INIS)

    Yumatov, V.D.; Murakhtanov, V.V.; Salakhutdinov, N.F.; Okotrub, A.V.; Mazalov, L.N.; Logunova, L.G.; Koptyug, V.A.; Furin, G.G.

    1988-01-01

    The electronic structure of the nitrobenzene molecule has been studied by x-ray spectroscopy with the aid of quantum-chemical calculations. The structure of the molecular orbitals of nitrobenzene has been compared with the structure of benzene and nitrogen dioxide. It has been shown in the framework of a fragment-by-fragment analysis that the interaction of the highest occupied π orbitals of the benzene ring and the nitro group is weak

  1. High-resolution broadband terahertz spectroscopy via electronic heterodyne detection of photonically generated terahertz frequency comb.

    Science.gov (United States)

    Pavelyev, D G; Skryl, A S; Bakunov, M I

    2014-10-01

    We report an alternative approach to the terahertz frequency-comb spectroscopy (TFCS) based on nonlinear mixing of a photonically generated terahertz pulse train with a continuous wave signal from an electronic synthesizer. A superlattice is used as a nonlinear mixer. Unlike the standard TFCS technique, this approach does not require a complex double-laser system but retains the advantages of TFCS-high spectral resolution and wide bandwidth.

  2. Plasma emission spectroscopy of solids irradiated by intense XUV pulses from a free electron laser

    Czech Academy of Sciences Publication Activity Database

    Dzelzainis, T.W.J.; Chalupský, Jaromír; Fajardo, M.; Fäustlin, R.; Heimann, P.A.; Hájková, Věra; Juha, Libor; Jurek, Karel; Khattak, F.Y.; Kozlová, Michaela; Krzywinski, J.; Lee, R. W.; Nagler, B.; Nelson, A.J.; Rosmej, F.B.; Soberierski, R.; Toleikis, S.; Tschentscher, T.; Vinko, S.M.; Wark, J. S.; Whitcher, T.; Riley, D.

    2010-01-01

    Roč. 6, č. 1 (2010), 109-112 ISSN 1574-1818 R&D Projects: GA MŠk LC510; GA MŠk(CZ) LC528; GA MŠk LA08024; GA AV ČR IAAX00100903 Institutional research plan: CEZ:AV0Z10100523; CEZ:AV0Z10100521 Keywords : XUV emission spectroscopy * free-electron laser * warm dense matter Subject RIV: BH - Optics, Masers, Lasers Impact factor: 1.206, year: 2010

  3. Electron momentum spectroscopy of solids by the (e,2e) reaction

    International Nuclear Information System (INIS)

    Kheifets, A.S.; Vos, M.; Canney, S.A.; Guo, X.; McCarthy, I.E.

    1996-08-01

    Recent developments in (e,2e) momentum spectroscopy have resulted in the study of a diverse range of solid targets. These studies have revealed the electronic structure of solids in much more detail that was previously available using this technique. The method is now capable of producing quantitative data on energy-resolved momentum density of solids. A summary of these results is presented, in particular for aluminium, aluminium oxides and graphite. 26 refs., 9 figs

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

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Mingsen [Department of Physics, Guizhou University, Guiyang, 550025 (China); Guizhou Provincial Key Laboratory of Computational Nano-Material Science, Institute of Applied Physics, Guizhou Normal College, Guiyang, 550018 (China); Ye, Gui; Jiang, Jun, E-mail: jiangj1@ustc.edu.cn [Department of Chemical Physics, School of Chemistry and Materials Science, University of Science and Technology of China, Hefei, 230026 (China); Cai, Shaohong, E-mail: caish@mail.gufe.edu.cn [Department of Physics, Guizhou University, Guiyang, 550025 (China); Guizhou Key Laboratory of Economic System Simulation, Guizhou University of Finance and Economics, Guiyang, 550004 (China); Sun, Guangyu [Guizhou Provincial Key Laboratory of Computational Nano-Material Science, Institute of Applied Physics, Guizhou Normal College, Guiyang, 550018 (China)

    2015-01-15

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

  6. Electronic processes in TTF-derived complexes studied by IR spectroscopy

    Science.gov (United States)

    Graja, Andrzej

    2001-09-01

    We focus our attention on the plasma-edge-like dispersion of the reflectance spectra of the selected bis(ethylenodithio)tetrathiafulvalene (BEDT-TTF)-derived organic conductors. The standard procedure to determine the electron transport parameters in low-dimensional organic conductors consists of fitting the appropriate theoretical models with the experimental reflectance data. This procedure provides us with basic information like plasma frequency, the optical effective mass of charge carriers, their number, mean free path and damping constant. Therefore, it is concluded that the spectroscopy is a powerful tool to study the electronic processes in conducting organic solids.

  7. X-ray imaging and spectroscopy of individual cobalt nanoparticles using photoemission electron microscopy

    International Nuclear Information System (INIS)

    Fraile Rodriguez, A.; Nolting, F.; Bansmann, J.; Kleibert, A.; Heyderman, L.J.

    2007-01-01

    Photoemission electron microscopy (PEEM) was employed for X-ray imaging and absorption spectroscopy of individual cobalt nanoparticles as small as 8 nm grown using an arc ion cluster source. Using lithographic markers on the samples we were able to identify the same particles with PEEM and scanning electron microscopy. Significant variations in the shape of the X-ray absorption spectra between different cobalt particles were detected. Furthermore, our data suggest that distinctive spectral information about the individual particles, such as the quenching of oxide-related features and changes in the cobalt L 3 -edge intensity, cancel out and cannot be detected in the measurement over an ensemble of particles

  8. Vacuum ultra-violet and electron energy loss spectroscopy of gaseous and solid organic compounds

    International Nuclear Information System (INIS)

    Koch, E.E.; Otto, A.

    1976-01-01

    The experimental arrangements used by the authors for the study of optical vacuum ultra-violet and electron energy loss spectra of organic compounds are described and some theoretical aspects of studies of higher excited states are considered. Results for alkanes, benzene, naphthalene, anthracene and some more complex hydrocarbons are reviewed. Recent results obtained by reflection and electron energy loss spectroscopy for single crystals of anthracene are included and their relevance for gas phase work as well as for the understanding of exciton effects in organic solids is described. (author)

  9. 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.

  10. 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....

  11. Positron annihilation induced Auger electron spectroscopy and its implementation at accelerator based low energy positron factories

    International Nuclear Information System (INIS)

    Weiss, A.; Koeymen, A.R.; Mehl, D.; Lee, K.H.; Yang Gimo; Jensen, K.

    1991-01-01

    Positron annihilation induced auger electron spectroscopy (PAES) makes use of a beam of low energy positrons to excite Auger transitions by annihilating core electrons. The large secondary electron background usually present in Auger spectra can be eliminated by setting the positron beam energy well below the Auger electron energy. This allows true Auger lineshapes to be obtained. Further, because the positron is localized just outside the surface before it annihilates, PAES is extremely sensitive to the topmost atomic layer. Recent PAES results obtained at the University of Texas at Arlington will be presented. In addition, the use of high resolution energy analyzers with multichannel particle detection schemes to prevent problems due to the high data rates associated with accelerator based positron beams will be discussed. (orig.)

  12. Electron irradiated liquid encapsulated Czochralski grown undoped gallium antimonide studied by positron lifetime spectroscopy and photoluminescence

    International Nuclear Information System (INIS)

    Ma, S K; Lui, M K; Ling, C C; Fung, S; Beling, C D; Li, K F; Cheah, K W; Gong, M; Hang, H S; Weng, H M

    2004-01-01

    Electron irradiated undoped liquid encapsulated Czochralski (LEC) grown GaSb samples were studied by positron lifetime spectroscopy (PLS) and photoluminescence (PL). In addition to the 315 ps component reported in the previous studies, another defect with a lifetime of 280 ps was also identified in the present electron irradiated samples. The bulk lifetime of the GaSb material was found to be 258 ps. The V Ga,280ps and the V Ga,315ps defects were associated with two independent Ga vacancy related defects having different microstructures. The well known 777 meV PL signal (usually band A) was also observed in the electron irradiated undoped GaSb samples. The band A intensity decreases with increasing electron irradiation dosage and it disappears after the 300 deg. C annealing regardless of the irradiation dosage. The origin of the band A signal is also discussed

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

    International Nuclear Information System (INIS)

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

    2007-01-01

    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

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

    International Nuclear Information System (INIS)

    Krishnan, K.M.

    1989-04-01

    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

  15. Photoelectron and electron momentum spectroscopy of 1-butene at benchmark theoretical levels

    International Nuclear Information System (INIS)

    Shojaei, S H Reza; Morini, Filippo; Hajgató, Bálazs; Deleuze, Michael S

    2011-01-01

    The results of experimental studies of the valence electronic structure of 1-butene employing photoelectron spectroscopy as well as electron momentum spectroscopy are interpreted on the ground of quantitative calculations of one-electron and shake-up ionization energies and of the related Dyson orbitals, using one-particle Green's function theory in conjunction with the third-order algebraic diagrammatic construction scheme (ADC(3)). Comparison is made with simulations of (e, 2e) electron momentum distributions obtained from standard (B3LYP) Kohn-Sham orbitals. Our analysis is based on highly quantitative determinations of the energy difference between the cis and gauche (C 1 ) conformers, within ∼0.02 kcal mol -1 accuracy, and a thermostatistical evaluation thereby of conformer weights beyond the level of the rigid rotor harmonic oscillator approximation. Relative entropies are found to be particularly sensitive to hindered rotations. The shake-up onset is located at 15.9 eV, and the orbital picture of ionization breaks down completely at electron binding energies above 19 eV. If the available experimental momentum profiles demonstrate the dominance of the C 1 conformer, they are in this case clearly not sensitive enough to the molecular conformation for evaluating conformer abundances with accuracies better than 10% due to the limited energy and momentum resolutions and likely physical complications.

  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. © 2014 Institute of Food Technologists®

  17. Development of time-resolved electron momentum spectroscopy. Toward real-time imaging of frontier electrons in molecular reactions

    International Nuclear Information System (INIS)

    Yamazaki, M.; Takahashi, M.

    2016-01-01

    This report will introduce a new experimental technique to readers, which we would like to propose towards advances in the field of molecular reaction dynamics. It is time-resolved electron momentum spectroscopy and aims to take in momentum space snapshots of the rapid change of molecular orbitals, which is the driving force behind any structural changes occurring in transient molecules. Following a description of the working principle of the technique, some preliminary result will be presented in order to illustrate the current performance of the apparatus. (author)

  18. 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...

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

    Science.gov (United States)

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

    2013-04-28

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

  20. Soft x-ray spectroscopy studies of novel electronic materials using synchrotron radiation

    Science.gov (United States)

    Newby, David, Jr.

    Soft x-ray spectroscopy can provide a wealth of information on the electronic structure of solids. In this work, a suite of soft x-ray spectroscopies is applied to organic and inorganic materials with potential applications in electronic and energy generation devices. Using the techniques of x-ray absorption (XAS), x-ray emission spectroscopy (XES), and x-ray photoemission spectroscopy (XPS), the fundamental properties of these different materials are explored. Cycloparaphenylenes (CPPs) are a recently synthesized family of cyclic hydrocarbons with very interesting properties and many potential applications. Unusual UV/Visible fluorescence trends have spurred a number of theoretical investigations into the electronic properties of the CPP family, but thus far no comprehensive electronic structure measurements have been conducted. XPS, XAS, and XES data for two varieties, [8]- and [10]-CPP, are presented here, and compared with the results of relevant DFT calculations. Turning towards more application-centered investigations, similar measurements are applied to two materials commonly used in solid oxide fuel cell (SOFC) cathodes: La1-xSrxMnO 3 (LSMO) and La1-xSr1- xCo1-yFe yO3 (LSCF). Both materials are structurally perovskites, but they exhibit strikingly different electronic properties. SOFC systems very efficiently produce electricity by catalyzing reactions between oxygen and petroleum-based hydrocarbons at high temperatures (> 800 C). Such systems are already utilized to great effect in many industries, but more widespread adoption could be had if the cells could operate at lower temperatures. Understanding the electronic structure and operational evolution of the cathode materials is essential for the development of better low-temperature fuel cells. LSCF is a mixed ion-electron conductor which holds promise for low-temperature SOFC applications. XPS spectra of LSCF thin films are collected as the films are heated and gas-dosed in a controlled environment. The

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-07-15

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

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

    Science.gov (United States)

    Shin, Young-Min; Figora, Michael

    2017-10-01

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

  3. 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.

  4. Dipole and Coulomb forces in electron capture dissociation and electron transfer dissociation mass spectroscopy.

    Science.gov (United States)

    Świerszcz, Iwona; Skurski, Piotr; Simons, Jack

    2012-02-23

    Ab initio electronic structure calculations were performed on a doubly charged polypeptide model H(+)-Lys(Ala)(19)-CO-CH(NH(2))-CH(2)-SS-CH(2)-(NH(2))CH-CO-(Ala)(19)-Lys-H(+) consisting of a C-terminal protonated Lys followed by a 19-Ala α-helix with a 20th Ala-like unit whose side chain is linked by a disulfide bond to a corresponding Ala-like unit connected to a second 19-Ala α-helix terminated by a second C-terminal-protonated Lys. The Coulomb potentials arising from the two charged Lys residues and dipole potentials arising from the two oppositely directed 72 D dipoles of the α-helices act to stabilize the SS bond's σ* orbital. The Coulomb potentials provide stabilization of 1 eV, while the two large dipoles generate an additional 4 eV. Such stabilization allows the SS σ* orbital to attach an electron and thereby generate disulfide bond cleavage products. Although calculations are performed only on SS bond cleavage, discussion of N-C(α) bond cleavage caused by electron attachment to amide π* orbitals is also presented. The magnitudes of the stabilization energies as well as the fact that they arise from Coulomb and dipole potentials are supported by results on a small model system consisting of a H(3)C-SS-CH(3) molecule with positive and negative fractional point charges to its left and right designed to represent (i) two positive charges ca. 32 Å distant (i.e., the two charged Lys sites of the peptide model) and (ii) two 72 D dipoles (i.e., the two α-helices). Earlier workers suggested that internal dipole forces in polypeptides could act to guide incoming free electrons (i.e., in electron capture dissociation (ECD)) toward the positive end of the dipole and thus affect the branching ratios for cleaving various bonds. Those workers argued that, because of the huge mass difference between an anion donor and a free electron, internal dipole forces would have a far smaller influence over the trajectory of a donor (i.e., in electron transfer dissociation

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-11-15

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

  6. Superatom spectroscopy and the electronic state correlation between elements and isoelectronic molecular counterparts.

    Science.gov (United States)

    Peppernick, Samuel J; Gunaratne, K D Dasitha; Castleman, A W

    2010-01-19

    Detailed in the present investigation are results pertaining to the photoelectron spectroscopy of negatively charged atomic ions and their isoelectronic molecular counterparts. Experiments utilizing the photoelectron imaging technique are performed on the negative ions of the group 10 noble metal block (i.e. Ni-, Pd-, and Pt-) of the periodic table at a photon energy of 2.33 eV (532 nm). The accessible electronic transitions, term energies, and orbital angular momentum components of the bound electronic states in the atom are then compared with photoelectron images collected for isoelectronic early transition metal heterogeneous diatomic molecules, M-X- (M = Ti,Zr,W; X = O or C). A superposition principle connecting the spectroscopy between the atomic and molecular species is observed, wherein the electronic structure of the diatomic is observed to mimic that present in the isoelectronic atom. The molecular ions studied in this work, TiO-, ZrO-, and WC- can then be interpreted as possessing superatomic electronic structures reminiscent of the isoelectronic elements appearing on the periodic table, thereby quantifying the superatom concept.

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

    International Nuclear Information System (INIS)

    Badot, Jean-Claude; Lestriez, Bernard; Dubrunfaut, Olivier

    2016-01-01

    Highlights: • Broadband dielectric spectroscopy measures the multiscale electronic conductivity from macroscopic to interatomic sizes. • There is an influence of the surface states on the electronic transfer of powdered materials (e.g. thin insulating layer of Li_2CO_3 on LiNiO_2 and carbon coating on LiFePO_4). • Electrical relaxations resulting from the interfacial polarizations at the different scales of the carbon black network are evidenced. - Abstract: Broadband dielectric spectroscopy (BDS) is used to measure complex permittivity and conductivity of conducting materials for lithium batteries at frequencies from a few Hz to several GHz with network and impedance analysers. Under the influence of an electric field, there will be charge density fluctuations in the conductor mainly due to electronic transfer. These fluctuations result in dielectric relaxations for frequencies below 100 GHz. The materials are compacted powders in which each element (particles, agglomerates of particles) can have different sizes and morphologies. In the present review, studies are reported on the influence of surface states in LiNiO_2 (ageing and degradation in air) and LiFePO_4 (carbon coating thin layer), and on a composite electrode based on the lithium trivanadate (Li_1_._1V_3O_8) active material. The results have shown that the BDS technique is very sensitive to the different scales of materials architectures involved in electronic transport, from interatomic distances to macroscopic sizes.

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

    International Nuclear Information System (INIS)

    Dauth, B.H.

    1989-08-01

    The electronic structure of various polycrystalline samples including the new YBaCuO- and BiCaSrCuO- high T c 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-2p 3/2 - 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. A UniChem and electron momentum spectroscopy investigations into the valence electronic structure of trans 1,3 butadiene

    Energy Technology Data Exchange (ETDEWEB)

    Michalewicz, M.T. [CSIRO, Supercomputing Support Group, Carlton, VIC (Australia). Division of Information Technology; Winkler, D.A. [Commonwealth Scientific and Industrial Research Organisation (CSIRO), Clayton, VIC (Australia). Div. of Chemical Physics; Brunger, M.J.; McCarthy, L.E. [Flinders Univ. of South Australia, Bedford Park, SA (Australia). School of Physical Sciences; Von Niessen, W. [Flinders Univ. of South Australia, Bedford Park, SA (Australia). School of Physical Sciences

    1996-09-01

    The experimental (e,2e) coincidence spectroscopy, known as electron momentum spectroscopy (EMS) was applied to the trans 1,3 butadiene (C{sub 4}H{sub 6}) molecule with detailed binding energy spectra and orbital momentum distributions (MDs) being measured. A small selection of this data is presented. The usage of UniChem computational chemistry codes for the Flinders-developed AMOLD program allows to calculate theoretical MDs for each orbital, to help elucidate the valence electronic structure of butadiene. The results of the many-body Green`s function calculation is also presented, to the ADC(3) level, for the binding energies and spectroscopic factors of the respective orbitals of C{sub 4}H{sub 6}. A critical comparison between the experimental and theoretical MDs allows to determine the optimum wavefunction from the basis sets studied. The determination of the wavefunction then allows to make further use of the UniChem package to derive butadiene`s chemically interesting molecular properties. A summary of these results and comparison of them with the previous results of other workers is presented. 23 refs., 2 tabs., 2 figs.

  10. A UniChem and electron momentum spectroscopy investigations into the valence electronic structure of trans 1,3 butadiene

    International Nuclear Information System (INIS)

    Michalewicz, M.T.; Winkler, D.A.; Brunger, M.J.; McCarthy, L.E.; Von Niessen, W.

    1996-09-01

    The experimental (e,2e) coincidence spectroscopy, known as electron momentum spectroscopy (EMS) was applied to the trans 1,3 butadiene (C 4 H 6 ) molecule with detailed binding energy spectra and orbital momentum distributions (MDs) being measured. A small selection of this data is presented. The usage of UniChem computational chemistry codes for the Flinders-developed AMOLD program allows to calculate theoretical MDs for each orbital, to help elucidate the valence electronic structure of butadiene. The results of the many-body Green's function calculation is also presented, to the ADC(3) level, for the binding energies and spectroscopic factors of the respective orbitals of C 4 H 6 . A critical comparison between the experimental and theoretical MDs allows to determine the optimum wavefunction from the basis sets studied. The determination of the wavefunction then allows to make further use of the UniChem package to derive butadiene's chemically interesting molecular properties. A summary of these results and comparison of them with the previous results of other workers is presented. 23 refs., 2 tabs., 2 figs

  11. Depth-selective X-ray absorption spectroscopy by detection of energy-loss Auger electrons

    Energy Technology Data Exchange (ETDEWEB)

    Isomura, Noritake, E-mail: isomura@mosk.tytlabs.co.jp [Toyota Central R& D Labs., Inc., 41-1 Yokomichi, Nagakute, Aichi 480-1192 (Japan); Soejima, Narumasa; Iwasaki, Shiro [Toyota Central R& D Labs., Inc., 41-1 Yokomichi, Nagakute, Aichi 480-1192 (Japan); Nomoto, Toyokazu; Murai, Takaaki [Aichi Synchrotron Radiation Center (AichiSR), 250-3 Minamiyamaguchi-cho, Seto, Aichi 489-0965 (Japan); Kimoto, Yasuji [Toyota Central R& D Labs., Inc., 41-1 Yokomichi, Nagakute, Aichi 480-1192 (Japan)

    2015-11-15

    Graphical abstract: - Highlights: • A unique XAS method is proposed for depth profiling of chemical states. • PEY mode detecting energy-loss electrons enables a variation in the probe depth. • Si K-edge XAS spectra of the Si{sub 3}N{sub 4}/SiO{sub 2}/Si multilayer films have been investigated. • Deeper information was obtained in the spectra measured at larger energy loss. • Probe depth could be changed by the selection of the energy of detected electrons. - Abstract: A unique X-ray absorption spectroscopy (XAS) method is proposed for depth profiling of chemical states in material surfaces. Partial electron yield mode detecting energy-loss Auger electrons, called the inelastic electron yield (IEY) mode, enables a variation in the probe depth. As an example, Si K-edge XAS spectra for a well-defined multilayer sample (Si{sub 3}N{sub 4}/SiO{sub 2}/Si) have been investigated using this method at various kinetic energies. We found that the peaks assigned to the layers from the top layer to the substrate appeared in the spectra in the order of increasing energy loss relative to the Auger electrons. Thus, the probe depth can be changed by the selection of the kinetic energy of the energy loss electrons in IEY-XAS.

  12. Depth-selective X-ray absorption spectroscopy by detection of energy-loss Auger electrons

    International Nuclear Information System (INIS)

    Isomura, Noritake; Soejima, Narumasa; Iwasaki, Shiro; Nomoto, Toyokazu; Murai, Takaaki; Kimoto, Yasuji

    2015-01-01

    Graphical abstract: - Highlights: • A unique XAS method is proposed for depth profiling of chemical states. • PEY mode detecting energy-loss electrons enables a variation in the probe depth. • Si K-edge XAS spectra of the Si_3N_4/SiO_2/Si multilayer films have been investigated. • Deeper information was obtained in the spectra measured at larger energy loss. • Probe depth could be changed by the selection of the energy of detected electrons. - Abstract: A unique X-ray absorption spectroscopy (XAS) method is proposed for depth profiling of chemical states in material surfaces. Partial electron yield mode detecting energy-loss Auger electrons, called the inelastic electron yield (IEY) mode, enables a variation in the probe depth. As an example, Si K-edge XAS spectra for a well-defined multilayer sample (Si_3N_4/SiO_2/Si) have been investigated using this method at various kinetic energies. We found that the peaks assigned to the layers from the top layer to the substrate appeared in the spectra in the order of increasing energy loss relative to the Auger electrons. Thus, the probe depth can be changed by the selection of the kinetic energy of the energy loss electrons in IEY-XAS.

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

    Science.gov (United States)

    Bennett, Kochise; Kowalewski, Markus; Mukamel, Shaul

    2016-02-09

    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.

  14. Gamma-induced Positron Spectroscopy (GiPS) at a superconducting electron linear accelerator

    International Nuclear Information System (INIS)

    Butterling, Maik; Anwand, Wolfgang; Cowan, Thomas E.; Hartmann, Andreas; Jungmann, Marco; Krause-Rehberg, Reinhard; Krille, Arnold; Wagner, Andreas

    2011-01-01

    A new and unique setup for Positron Annihilation Spectroscopy has been established and optimized at the superconducting linear electron accelerator ELBE at Helmholtz-Zentrum Dresden-Rossendorf (Germany). The intense, pulsed (26 MHz) photon source (bremsstrahlung with energies up to 16 MeV) is used to generate positrons by means of pair production throughout the entire sample volume. Due to the very short gamma bunches (< 5 ps temporal length), the facility for Gamma-induced Positron Spectroscopy (GiPS) is suitable for positron lifetime spectroscopy using the accelerator's radiofrequency as time reference. Positron lifetime and Doppler broadening Spectroscopy are employed by a coincident measurement (Age-Momentum Correlation) of the time-of-arrival and energy of the annihilation photons which in turn significantly reduces the background of scattered photons resulting in spectra with high signal to background ratios. Simulations of the setup using the GEANT4 framework have been performed to yield optimum positron generation rates for various sample materials and improved background conditions.

  15. Gamma-induced Positron Spectroscopy (GiPS) at a superconducting electron linear accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Butterling, Maik, E-mail: maik.butterling@googlemail.com [Martin-Luther University, Dept. of Physics, 06099 Halle (Germany); Institute of Radiation Physics, Helmholtz-Zentrum, Dresden-Rossendorf, P.O. Box 510119, 01314 Dresden (Germany); Anwand, Wolfgang; Cowan, Thomas E.; Hartmann, Andreas [Institute of Radiation Physics, Helmholtz-Zentrum, Dresden-Rossendorf, P.O. Box 510119, 01314 Dresden (Germany); Jungmann, Marco; Krause-Rehberg, Reinhard [Martin-Luther University, Dept. of Physics, 06099 Halle (Germany); Krille, Arnold; Wagner, Andreas [Institute of Radiation Physics, Helmholtz-Zentrum, Dresden-Rossendorf, P.O. Box 510119, 01314 Dresden (Germany)

    2011-11-15

    A new and unique setup for Positron Annihilation Spectroscopy has been established and optimized at the superconducting linear electron accelerator ELBE at Helmholtz-Zentrum Dresden-Rossendorf (Germany). The intense, pulsed (26 MHz) photon source (bremsstrahlung with energies up to 16 MeV) is used to generate positrons by means of pair production throughout the entire sample volume. Due to the very short gamma bunches (< 5 ps temporal length), the facility for Gamma-induced Positron Spectroscopy (GiPS) is suitable for positron lifetime spectroscopy using the accelerator's radiofrequency as time reference. Positron lifetime and Doppler broadening Spectroscopy are employed by a coincident measurement (Age-Momentum Correlation) of the time-of-arrival and energy of the annihilation photons which in turn significantly reduces the background of scattered photons resulting in spectra with high signal to background ratios. Simulations of the setup using the GEANT4 framework have been performed to yield optimum positron generation rates for various sample materials and improved background conditions.

  16. Deuterium trapping at vacancy clusters in electron/neutron-irradiated tungsten studied by positron annihilation spectroscopy

    Science.gov (United States)

    Toyama, T.; Ami, K.; Inoue, K.; Nagai, Y.; Sato, K.; Xu, Q.; Hatano, Y.

    2018-02-01

    Deuterium trapping at irradiation-induced defects in tungsten, a candidate material for plasma facing components in fusion reactors, was revealed by positron annihilation spectroscopy. Pure tungsten was electron-irradiated (8.5 MeV at ∼373 K and to a dose of ∼1 × 10-3 dpa) or neutron-irradiated (at 573 K to a dose of ∼0.3 dpa), followed by post-irradiation annealing at 573 K for 100 h in deuterium gas of ∼0.1 MPa. In both cases of electron- or neutron-irradiation, vacancy clusters were found by positron lifetime measurements. In addition, positron annihilation with deuterium electrons was demonstrated by coincidence Doppler broadening measurements, directly indicating deuterium trapping at vacancy-type defects. This is expected to cause significant increase in deuterium retention in irradiated-tungsten.

  17. X-ray fluorescence/Auger-electron coincidence spectroscopy of vacancy cascades in atomic argon

    International Nuclear Information System (INIS)

    Arp, U.

    1996-01-01

    Argon L 2.3 -M 2.3 M 2.3 Auger-electron spectra were measured in coincidence with Kα fluorescent x-rays in studies of Ar K-shell vacancy decays at several photon energies above the K-threshold and on the 1s-4p resonance in atomic argon. The complex spectra recorded by conventional electron spectroscopy are greatly simplified when recorded in coincidence with fluorescent x-rays, allowing a more detailed analysis of the vacancy cascade process. The resulting coincidence spectra are compared with Hartree-Fock calculations which include shake-up transitions in the resonant case. Small energy shifts of the coincidence electron spectra are attributed to post-collision interaction with 1s photoelectrons

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

    CERN Document Server

    Brydson, R; Brown, A

    2003-01-01

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

  19. Fine structures of atomic excited states: precision atomic spectroscopy and electron-ion collision process

    International Nuclear Information System (INIS)

    Gao Xiang; Cheng Cheng; Li Jiaming

    2011-01-01

    Scientific research fields for future energies such as inertial confinement fusion researches and astrophysics studies especially with satellite observatories advance into stages of precision physics. The relevant atomic data are not only enormous but also of accuracy according to requirements, especially for both energy levels and the collision data. The fine structure of high excited states of atoms and ions can be measured by precision spectroscopy. Such precision measurements can provide not only knowledge about detailed dynamics of electron-ion interactions but also a bench mark examination of the accuracy of electron-ion collision data, especially incorporating theoretical computations. We illustrate that by using theoretical calculation methods which can treat the bound states and the adjacent continua on equal footing. The precision spectroscopic measurements of excited fine structures can be served as stringent tests of electron-ion collision data. (authors)

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

    Energy Technology Data Exchange (ETDEWEB)

    Goldmann, Maximilian; Miguel-Sánchez, Javier; West, Adam H. C.; Yoder, Bruce L.; Signorell, Ruth, E-mail: rsignorell@ethz.ch [Laboratory of Physical Chemistry, ETH Zürich, Vladimir-Prelog-Weg 2, 8093 Zürich (Switzerland)

    2015-06-14

    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.

  1. Probing a molecular electronic transition by two-colour sum-frequency generation spectroscopy

    International Nuclear Information System (INIS)

    Humbert, C.; Dreesen, L.; Nihonyanagi, S.; Masuda, T.; Kondo, T.; Mani, A.A.; Uosaki, K.; Thiry, P.A.; Peremans, A.

    2003-01-01

    We demonstrate that a new emerging technique, two-colour sum-frequency generation (SFG) spectroscopy, can be used to probe the molecular electronic properties of self-assembled monolayers (SAMs). In the CH spectral range (2800-3200 cm -1 ), we show that the sum-frequency generation signal of a porphyrin alkanethiol derivative adsorbed on Pt(1 1 1) reaches a maximum intensity at ∼435 nm SFG wavelength. This wavelength corresponds to the porphyrin moiety specific π-π* molecular electronic transition which is called the Soret or B band. This resonant behaviour is not observed for 1-dodecanethiol SAMs, which are devoid of molecular electronic transition in the investigated visible spectral range

  2. SOR-RING: an electron storage ring dedicated to spectroscopy, 2

    International Nuclear Information System (INIS)

    Kitamura, H.; Miyahara, T.; Sato, S.; Watanabe, M.; Mitani, S.

    1976-01-01

    A 300 MeV electron storage ring to be used exclusively as a synchrotron radiation source for spectroscopy has been constructed in Institute for Nuclear Study (INS), University of Tokyo, Tanashi. Its useful spectral range lies between 40 and 2200 A. The 1.3 GeV electron synchrotron of INS currently being operated for high energy particle experiments serves as an injector. Electron beams are extracted from the synchrotron at 300 MeV, transported about twenty meters, and injected to the ring one pulse per second. In the test operation a current of 10 mA was stored with a lifetime of one hour, while the design goal determined by the Touschek effect is 100 mA with one hour, for operation in 300 MeV. Increase of operating energy up to 375 MeV is feasible with a minor modification of the present design. (auth.)

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

    International Nuclear Information System (INIS)

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

    2016-01-01

    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. (paper)

  4. Electron transfer dynamics of triphenylamine dyes bound to TiO2 nanoparticles from femtosecond stimulated Raman spectroscopy

    KAUST Repository

    Hoffman, David P.; Lee, Olivia P.; Millstone, Jill E.; Chen, Mark S.; Su, Timothy A.; Creelman, Mark; Frechet, Jean; Mathies, Richard A.

    2013-01-01

    Interfacial electron transfer between sensitizers and semiconducting nanoparticles is a crucial yet poorly understood process. To address this problem, we have used transient absorption (TA) and femtosecond stimulated Raman spectroscopy (FSRS

  5. Electron spectroscopy in the X-ray range for occupied and free levels and the application to transition metal silicides

    International Nuclear Information System (INIS)

    Speier, W.

    1988-03-01

    Intermetallic compounds of transition metals are investigated by means of XPS, Bremsstrahlung Isochromate Spectroscopy and XAS. Occupied and free levels are characterized and moreover a systematic overview over the electronic structure of the transition element silicides is given. (BHO)

  6. spectroscopy

    African Journals Online (AJOL)

    Aghomotsegin

    2015-10-14

    Oct 14, 2015 ... characterized by using phenotypic, API and Fourier transform infrared (FTIR) spectroscopy methods. One hundred and fifty-seven (157) strains were isolated from 13 cheese samples, and identification test was performed for 83 strains. At the end of the study, a total of 22 Lactococcus sp., 36 Enterecoccus ...

  7. Process analysis of recycled thermoplasts from consumer electronics by laser-induced plasma spectroscopy.

    Science.gov (United States)

    Fink, Herbert; Panne, Ulrich; Niessner, Reinhard

    2002-09-01

    An experimental setup for direct elemental analysis of recycled thermoplasts from consumer electronics by laser-induced plasma spectroscopy (LIPS, or laser-induced breakdown spectroscopy, LIBS) was realized. The combination of a echelle spectrograph, featuring a high resolution with a broad spectral coverage, with multivariate methods, such as PLS, PCR, and variable subset selection via a genetic algorithm, resulted in considerable improvements in selectivity and sensitivity for this complex matrix. With a normalization to carbon as internal standard, the limits of detection were in the ppm range. A preliminary pattern recognition study points to the possibility of polymer recognition via the line-rich echelle spectra. Several experiments at an extruder within a recycling plant demonstrated successfully the capability of LIPS for different kinds of routine on-line process analysis.

  8. Dual-comb spectroscopy of molecular electronic transitions in condensed phases

    Science.gov (United States)

    Cho, Byungmoon; Yoon, Tai Hyun; Cho, Minhaeng

    2018-03-01

    Dual-comb spectroscopy (DCS) utilizes two phase-locked optical frequency combs to allow scanless acquisition of spectra using only a single point detector. Although recent DCS measurements demonstrate rapid acquisition of absolutely calibrated spectral lines with unprecedented precision and accuracy, complex phase-locking schemes and multiple coherent averaging present significant challenges for widespread adoption of DCS. Here, we demonstrate Global Positioning System (GPS) disciplined DCS of a molecular electronic transition in solution at around 800 nm, where the absorption spectrum is recovered by using a single time-domain interferogram. We anticipate that this simplified dual-comb technique with absolute time interval measurement and ultrabroad bandwidth will allow adoption of DCS to tackle molecular dynamics investigation through its implementation in time-resolved nonlinear spectroscopic studies and coherent multidimensional spectroscopy of coupled chromophore systems.

  9. Formation and characterization of varied size germanium nanocrystals by electron microscopy, Raman spectroscopy, and photoluminescence

    DEFF Research Database (Denmark)

    Ou, Haiyan; Ou, Yiyu; Liu, Chuan

    2011-01-01

    Germanium nanocrystals are being extensively examined. Their unique optical properties (brought about by the quantum confinement effect) could potentially be applied in wide areas of nonlinear optics, light emission and solid state memory etc. In this paper, Ge nanocrystals embedded in a SiO2...... matrix were formed by complementary metal-oxide-semiconductor compatible technology, e.g. plasma enhanced chemical vapour deposition and annealing. Different sizes of the Ge nanocrystals were prepared and analyzed by transmission electron microscopy with respect to their size, distribution...... and crystallization. The samples of different size Ge nanocrystals embedded in the SiO2 matrix were characterized by Raman spectroscopy and photoluminescence. Interplayed size and strain effect of Ge nanocystals was demonstrated by Raman spectroscopy after excluding the thermal effect with proper excitation laser...

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

    Science.gov (United States)

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

    1997-01-01

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

  11. Multiphoton electronic-spin generation and transmission spectroscopy in n-type GaAs

    Energy Technology Data Exchange (ETDEWEB)

    Idrish Miah, M., E-mail: m.miah@griffith.edu.a [Department of Physics, University of Chittagong, Chittagong 4331 (Bangladesh)

    2011-01-17

    Multiphoton electronic-spin generation in semiconductors was investigated using differential transmission spectroscopy. The generation of the electronic spins in the semiconductor samples were achieved by multiphoton pumping with circularly polarized light beam and was probed by the spin-resolved transmission of the samples. The electronic spin-polarization of conduction band was estimated and was found to depend on the delay of the probe beam, temperature as well as on the multiphoton pumping energy. The temperature dependence showed a decrease of the spin-polarization with increasing temperature. The electronic spin-polarization was found to depolarize rapidly for multiphoton pumping energy larger than the energy gap of the split-off band to the conduction band. The results were compared with those obtained in one-photon pumping, which shows that an enhancement of the electronic spin-polarization was achieved in multiphoton pumping. The findings resulting from this investigation might have potential applications in opto-spintronics, where the generation of highly polarized electronic spins is required.

  12. Multiphoton electronic-spin generation and transmission spectroscopy in n-type GaAs

    International Nuclear Information System (INIS)

    Idrish Miah, M.

    2011-01-01

    Multiphoton electronic-spin generation in semiconductors was investigated using differential transmission spectroscopy. The generation of the electronic spins in the semiconductor samples were achieved by multiphoton pumping with circularly polarized light beam and was probed by the spin-resolved transmission of the samples. The electronic spin-polarization of conduction band was estimated and was found to depend on the delay of the probe beam, temperature as well as on the multiphoton pumping energy. The temperature dependence showed a decrease of the spin-polarization with increasing temperature. The electronic spin-polarization was found to depolarize rapidly for multiphoton pumping energy larger than the energy gap of the split-off band to the conduction band. The results were compared with those obtained in one-photon pumping, which shows that an enhancement of the electronic spin-polarization was achieved in multiphoton pumping. The findings resulting from this investigation might have potential applications in opto-spintronics, where the generation of highly polarized electronic spins is required.

  13. Delta electron spectroscopy for the study of the inner-shell excitation in heavy ion collisions

    International Nuclear Information System (INIS)

    Trollmann, G.

    1981-01-01

    In this thesis energy and angular differential cross sections of delta electrons from ion-atom collisions are measured and compared with different perturbation theories. Shell specific cross sections were obtained from electron-X-ray coincidences. Contradicting theoretical statements concerning the angular distribution of the electrons can be experimentally clarified, other predictions are verified. Starting from fast, strongly asymmetric collisions until to slow, more symmetric collisions the question of the disturbance of the stationary target state by the projectile and the formation of intermediate molecular state is studied. With the results of the measurement of the delta electrons it can be contributed to the clarification of the question for the physical origin of the continuous X-radiation in the energy range beyond the K-line of the heavier collision partner. It is shown that the secondary electron bremsstrahlung discussed as radiation source besides the molecular orbital (MO) radiation is in its intensity about more than one order of magnitude weaker than the measured X-radiation and is therefore excluded as dominant radiation. In the framework of this work an apparature was developed, which allows the electron spectroscopy in the energy range between 10 keV and 150 keV and the angular range between 5 degrees and 180 degrees for the absolute determination of double differential cross sections. (orig./HSI) [de

  14. Investigation of the molecular conformations of ethanol using electron momentum spectroscopy

    International Nuclear Information System (INIS)

    Ning, C G; Luo, Z H; Huang, Y R; Liu, K; Zhang, S F; Deng, J K; Hajgato, B; Morini, F; Deleuze, M S

    2008-01-01

    The valence electronic structure and momentum-space electron density distributions of ethanol have been investigated with our newly constructed high-resolution electron momentum spectrometer. The measurements are compared to thermally averaged simulations based on Kohn-Sham (B3LYP) orbital densities as well as one-particle Green's function calculations of ionization spectra and Dyson orbital densities, assuming Boltzmann's statistical distribution of the molecular structure over the two energy minima defining the anti and gauche conformers. One-electron ionization energies and momentum distributions in the outer-valence region were found to be highly dependent upon the molecular conformation. Calculated momentum distributions indeed very sensitively reflect the distortions and topological changes that molecular orbitals undergo due to the internal rotation of the hydroxyl group, and thereby exhibit variations which can be traced experimentally. The B3LYP model Kohn-Sham orbital densities are overall in good agreement with the experimental distributions, and closely resemble benchmark ADC(3) Dyson orbital densities. Both approaches fail to quantitatively reproduce the experimental momentum distributions characterizing the highest occupied molecular orbital. Since electron momentum spectroscopy measurements at various electron impact energies indicate that the plane wave impulse approximation is valid, this discrepancy between theory and experiment is tentatively ascribed to thermal disorder, i.e. large-amplitude and thermally induced dynamical distortions of the molecular structure in the gas phase

  15. A study of Al/Si interface by photoemission, Auger electron yield and Auger electron spectroscopies

    International Nuclear Information System (INIS)

    Kobayashi, K.L.I.; Barth, J.; Gerken, F.; Kunz, C.; Deutsches Elektronen-Synchrotron

    1980-06-01

    Photoemission, Auger electron yield and Auger electron spectra were observed for Al/Si(111) interfaces with various Al coverage prepared by successive deposition using a molecular beam source. The Al 3p derived states are introduced at around the top of the valence band by the Al coverage of less than one monolayer. The Al surface layer behaves as a 'metal' and the Fermi level is stabilized in the Al 3p derived states at about 0.3 eV above the top of the valence band of Si. The Schottky barrier height in this stage is about 0.8 eV and further increase in Al coverage does not change the barrier height. A covalent bonding model of the Al/Si interface based on the experimental results is proposed. The present result favors the on-top geometry of Al atoms on Si(111) surface among the geometries used in the pseudopotential calculation by Zhang and Schlueter. (orig.)

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

    International Nuclear Information System (INIS)

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

    2015-01-01

    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 2b 1 , 6a 1 , 4b 2 , and 1a 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 1 , B 1 , and B 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

  17. Development of wave length-dispersive soft x-ray emission spectrometers for transmission electron microscopes - an introduction of valence electron spectroscopy for transmission electron microscopy

    International Nuclear Information System (INIS)

    Terauchi, Masami; Koike, Masato; Fukushima, Kurio; Kimura, Atsushi

    2010-01-01

    Two types of wavelength-dispersive soft X-ray spectrometers, a high-dispersion type and a conventional one, for transmission electron microscopes were constructed. Those spectrometers were used to study the electronic states of valence electrons (bonding electrons). Both spectrometers extended the acceptable energy regions to higher than 2000 eV. The best energy resolution of 0.08 eV was obtained for an Al L-emission spectrum by using the high-dispersion type spectrometer. By using the spectrometer, C K-emission of carbon allotropes, Cu L-emission of Cu 1-x Zn x alloys and Pt M-emission spectra were presented. The FWHM value of 12 eV was obtained for the Pt Mα-emission peak. The performance of the conventional one was also presented for ZnS and a section specimen of a multilayer device. W-M and Si-K emissions were clearly resolved. Soft X-ray emission spectroscopy based on transmission electron microscopy (TEM) has an advantage for obtaining spectra from a single crystalline specimen with a defined crystal setting. As an example of anisotropic soft X-ray emission, C K-emission spectra of single crystalline graphite with different crystal settings were presented. From the spectra, density of states of π- and σ-bondings were separately derived. These results demonstrated a method to analyse the electronic states of valence electrons of materials in the nanometre scale based on TEM. (author)

  18. Measurement of the band gap by reflection electron energy loss spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Vos, Maarten, E-mail: maarten.vos@anu.edu.au [Electronic Materials Engineering Department, Research School of Physics and Engineering, The Australian National University, Canberra 0200 (Australia); King, Sean W. [Logic Technology Development, Intel Corporation, Hillsboro, OR 97124 (United States); French, Benjamin L. [Ocotillo Materials Laboratory, Intel Corporation, Chandler, AZ 85248 (United States)

    2016-10-15

    Highlights: • Semiconductors are measured (without surface preparation) using REELS. • At low beam energies it is difficult to measure band gap due to surface impurities. • At very high energies it is difficult to measure band gap due to recoil effect. • At intermediate energies (around 5 keV) one obtains a good estimate of the band gap. - Abstract: We investigate the possibilities of measuring the band gap of a variety of semiconductors and insulators by reflection electron energy loss spectroscopy without additional surface preparation. The band gap is a bulk property, whereas reflection energy loss spectroscopy is generally considered a surface sensitive technique. By changing the energy of the incoming electrons, the degree of surface sensitivity can be varied. Here, we present case studies to determine the optimum condition for the determination of the band gap. At very large incoming electron energies recoil effects interfere with the band gap determination, whereas at very low energies surface effects are obscuring the band gap without surface preparation. Using an incoming energy of 5 keV a reasonable estimate of the band gap is obtained in most cases.

  19. Multivariate statistical analysis of electron energy-loss spectroscopy in anisotropic materials

    International Nuclear Information System (INIS)

    Hu Xuerang; Sun Yuekui; Yuan Jun

    2008-01-01

    Recently, an expression has been developed to take into account the complex dependence of the fine structure in core-level electron energy-loss spectroscopy (EELS) in anisotropic materials on specimen orientation and spectral collection conditions [Y. Sun, J. Yuan, Phys. Rev. B 71 (2005) 125109]. One application of this expression is the development of a phenomenological theory of magic-angle electron energy-loss spectroscopy (MAEELS), which can be used to extract the isotropically averaged spectral information for materials with arbitrary anisotropy. Here we use this expression to extract not only the isotropically averaged spectral information, but also the anisotropic spectral components, without the restriction of MAEELS. The application is based on a multivariate statistical analysis of core-level EELS for anisotropic materials. To demonstrate the applicability of this approach, we have conducted a study on a set of carbon K-edge spectra of multi-wall carbon nanotube (MWCNT) acquired with energy-loss spectroscopic profiling (ELSP) technique and successfully extracted both the averaged and dichroic spectral components of the wrapped graphite-like sheets. Our result shows that this can be a practical alternative to MAEELS for the study of electronic structure of anisotropic materials, in particular for those nanostructures made of layered materials

  20. Analytical modeling of electron energy loss spectroscopy of graphene: Ab initio study versus extended hydrodynamic model.

    Science.gov (United States)

    Djordjević, Tijana; Radović, Ivan; Despoja, Vito; Lyon, Keenan; Borka, Duško; Mišković, Zoran L

    2018-01-01

    We present an analytical modeling of the electron energy loss (EEL) spectroscopy data for free-standing graphene obtained by scanning transmission electron microscope. The probability density for energy loss of fast electrons traversing graphene under normal incidence is evaluated using an optical approximation based on the conductivity of graphene given in the local, i.e., frequency-dependent form derived by both a two-dimensional, two-fluid extended hydrodynamic (eHD) model and an ab initio method. We compare the results for the real and imaginary parts of the optical conductivity in graphene obtained by these two methods. The calculated probability density is directly compared with the EEL spectra from three independent experiments and we find very good agreement, especially in the case of the eHD model. Furthermore, we point out that the subtraction of the zero-loss peak from the experimental EEL spectra has a strong influence on the analytical model for the EEL spectroscopy data. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Ultrafast carrier thermalization in lead iodide perovskite probed with two-dimensional electronic spectroscopy.

    Science.gov (United States)

    Richter, Johannes M; Branchi, Federico; Valduga de Almeida Camargo, Franco; Zhao, Baodan; Friend, Richard H; Cerullo, Giulio; Deschler, Felix

    2017-08-29

    In band-like semiconductors, charge carriers form a thermal energy distribution rapidly after optical excitation. In hybrid perovskites, the cooling of such thermal carrier distributions occurs on timescales of about 300 fs via carrier-phonon scattering. However, the initial build-up of the thermal distribution proved difficult to resolve with pump-probe techniques due to the requirement of high resolution, both in time and pump energy. Here, we use two-dimensional electronic spectroscopy with sub-10 fs resolution to directly observe the carrier interactions that lead to a thermal carrier distribution. We find that thermalization occurs dominantly via carrier-carrier scattering under the investigated fluences and report the dependence of carrier scattering rates on excess energy and carrier density. We extract characteristic carrier thermalization times from below 10 to 85 fs. These values allow for mobilities of 500 cm 2  V -1  s -1 at carrier densities lower than 2 × 10 19  cm -3 and limit the time for carrier extraction in hot carrier solar cells.Carrier-carrier scattering rates determine the fundamental limits of carrier transport and electronic coherence. Using two-dimensional electronic spectroscopy with sub-10 fs resolution, Richter and Branchi et al. extract carrier thermalization times of 10 to 85 fs in hybrid perovskites.

  2. Study on atomic and electronic structures of ceramic materials using spectroscopy, microscopy, and first principles calculation

    International Nuclear Information System (INIS)

    Mizoguchi, Teruyasu

    2011-01-01

    In this review, following two topics are introduced: 1) experimental and theoretical electron energy loss (EEL) near edge structures (ELNES) and X-ray absorption near edge structures (XANES), and 2) atomic and electronic structure analysis of ceramic interface by combing spectroscopy, microscopy, and first principles calculation. In the ELNES/XANES calculation, it is concluded that inclusion of core-hole effect in the calculation is essential. By combining high energy resolution observation and theoretical calculation, detailed analysis of the electronic structure is achieved. In addition, overlap population (OP) diagram is used to interpret the spectrum. In the case of AlN, sharp and intense first peak of N-K edge is found to reflect narrow dispersion of the conduction band bottom. By applying ELNES and the OP diagram to Cu/Al 2 O 3 heterointerface, it is revealed that intensity of prepeak in O-K edge is inverse proportional to interface strength. The relationships between atomic structure and defect energetics at SrTiO 3 grain boundary are also investigated, and reveal that the formation behavior of Ti vacancy is sensitive to the structural distortion. In addition, by using state-of-the-art spectroscopy, microscopy, and first principles calculations, atomic scale visualization of fluorine dopant in LaFeOAs and first principles calculation of HfO 2 phase transformation are demonstrated. (author)

  3. 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.

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

    International Nuclear Information System (INIS)

    Kaciulis, S.; Mezzi, A.; Balijepalli, S.K.; Lavorgna, M.; Xia, H.S.

    2015-01-01

    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 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

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

    Science.gov (United States)

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

    2017-11-01

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

  6. Measurement of the band gap by reflection electron energy loss spectroscopy

    International Nuclear Information System (INIS)

    Vos, Maarten; King, Sean W.; French, Benjamin L.

    2016-01-01

    Highlights: • Semiconductors are measured (without surface preparation) using REELS. • At low beam energies it is difficult to measure band gap due to surface impurities. • At very high energies it is difficult to measure band gap due to recoil effect. • At intermediate energies (around 5 keV) one obtains a good estimate of the band gap. - Abstract: We investigate the possibilities of measuring the band gap of a variety of semiconductors and insulators by reflection electron energy loss spectroscopy without additional surface preparation. The band gap is a bulk property, whereas reflection energy loss spectroscopy is generally considered a surface sensitive technique. By changing the energy of the incoming electrons, the degree of surface sensitivity can be varied. Here, we present case studies to determine the optimum condition for the determination of the band gap. At very large incoming electron energies recoil effects interfere with the band gap determination, whereas at very low energies surface effects are obscuring the band gap without surface preparation. Using an incoming energy of 5 keV a reasonable estimate of the band gap is obtained in most cases.

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

    Directory of Open Access Journals (Sweden)

    M. Salewski

    2017-08-01

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

  8. Electron beam exposure mechanisms in hydrogen silsesquioxane investigated by vibrational spectroscopy and in-situ electron beam induced desorption

    Energy Technology Data Exchange (ETDEWEB)

    Olynick, D.L.; Cord, B.; Schipotinin, A.; Ogletree, D.F.; Schuck, P.J.

    2009-11-13

    Hydrogen Silsesquioxane (HSQ) is used as a high-resolution resist with resolution down below 10nm half-pitch. This material or materials with related functionalities could have widespread impact in nanolithography and nanoscience applications if the exposure mechanism was understood and instabilities controlled. Here we have directly investigated the exposure mechanism using vibrational spectroscopy (both Raman and Fourier transform Infrared) and electron beam desorption spectrocscopy (EBDS). In the non-networked HSQ system, silicon atoms sit at the corners of a cubic structure. Each silicon is bonded to a hydrogen atom and bridges 3 oxygen atoms (formula: HSiO3/2). For the first time, we have shown, via changes in the Si-H2 peak at ~;;2200 cm -1 in the Raman spectra and the release of SiHx products in EBID, that electron-bam exposed materials crosslinks via a redistribution reaction. In addition, we observe the release of significantly more H2 than SiH2 during EBID, which is indicative of additional reaction mechanisms. Additionally, we compare the behavior of HSQ in response to both thermal and electron-beam induced reactions.

  9. A novel probe of intrinsic electronic structure: hard X-ray photoemission spectroscopy

    International Nuclear Information System (INIS)

    Takata, Y.; Tamasaku, K.; Nishino, Y.; Miwa, D.; Yabashi, M.; Ikenaga, E.; Horiba, K.; Arita, M.; Shimada, K.; Namatame, H.; Nohira, H.; Hattori, T.; Soedergren, S.; Wannberg, B.; Taniguchi, M.; Shin, S.; Ishikawa, T.; Kobayashi, K.

    2005-01-01

    We have realized hard X-ray (HX) photoemission spectroscopy (PES) with high throughput and high-energy resolution for core level and valence band studies using high-energy and high-brilliance synchrotron radiation at SPring-8. This is a brand new method because large escape depth of high-energy photoelectrons enables us to probe intrinsic bulk states free from surface condition. By use of a newly developed electron energy analyzer and well-focused X-rays, high-energy resolution of 75 meV (E/ΔE 79,000) was realized for 5.95 keV photoelectrons

  10. Characterization of a Fe inclusion in beryllium-matrix using auger electron spectroscopy

    International Nuclear Information System (INIS)

    Arkusk, R.; Moreno, D.; Simca, F.; Yeheskel, O.; Utzmoni, U.

    1991-04-01

    The auger electron spectroscopy techniques was employed to investigate the nature of an inclusion that had been revealed by radiography in a beryllium body produced by the hot isostatic press technique. The investigation's are that the inclusion is composed of several different iron-beryllium intermetallic compounds (BeFe 3 , BeFe 5 , Be 7 Fe). The conclusion drawn is that iron metal impurity was imbedded in the Be powder and that interdiffusion under the process's conditions gave rise to the enlarged inclusion. (author)

  11. Al-doped MgB_2 materials studied using electron paramagnetic resonance and Raman spectroscopy

    International Nuclear Information System (INIS)

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

    2016-01-01

    Undoped and aluminum (Al) doped magnesium diboride (MgB_2) samples were synthesized using a high-temperature solid-state synthesis method. The microscopic defect structures of Al-doped MgB_2 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 MgB_2. Above a certain level of Al doping, enhanced conductive properties of MgB_2 disappear due to filling of vacancies or trapping of Al in Mg-related vacancy sites.

  12. Application of electron energy loss spectroscopy for single wall carbon nanotubes (review)

    International Nuclear Information System (INIS)

    Mittal, N.; Jain, S.; Mittal, J.

    2015-01-01

    Electron energy loss spectroscopy (EELS) is among the few techniques that are available for the characterization of modified single wall carbon nanotubes (SWCNTs) having nanometer dimensions (~1-3 nm). CNTs can be modified either by surface functionalization or coating, between bundles of nanotubes by doping, intercalation and fully or partially filling the central core. EELS is an exclusive technique for the identification, composition analysis, and crystallization studies of the chemicals and materials used for the modification of SWCNTs. The present paper serves as a compendium of research work on the application of EELS for the characterization of modified SWCNTs. (authors)

  13. Electron collisions and rovibrational action spectroscopy of cold H3+ molecules

    International Nuclear Information System (INIS)

    Kreckel, H; Petrignani, A; Berg, M; Bing, D; Reinhardt, S; Altevogt, S; Buhr, H; Froese, M; Hoffmann, J; Jordon-Thaden, B; Krantz, C; Lestinsky, M; Mendes, M; Novotny, O; Novotny, S; Pedersen, H B; Orlov, D A; Mikosch, J; Wester, R; Plasil, R; GlosIk, J; Schwalm, D; Zajfman, D; Wolf, A

    2007-01-01

    Electron recombination of H 3 + has found a lot of attention due to its outstanding relevance for the chemistry of the interstellar medium (ISM) and its role as a benchmark for the treatment of dissociative recombination (DR) of polyatomic ions. We report DR measurements performed at the TSR storage ring utilizing a cryogenic ion trap injector. Furthermore, a chemical probing spectroscopy technique is described that allows for a very sensitive monitoring of the populated states inside the ion injector. Since H 3 + exists in two different nuclear spin modifications, a controlled manipulation of the ortho/para fraction is needed in order to perform state-selective measurements

  14. 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.

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

    Science.gov (United States)

    Hindle, Francis; Yang, Chun; Mouret, Gael; Cuisset, Arnaud; Bocquet, Robin; Lampin, Jean-François; Blary, Karine; Peytavit, Emilien; Akalin, Tahsin; Ducournau, Guillaume

    2009-01-01

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

    Science.gov (United States)

    Hindle, Francis; Yang, Chun; Mouret, Gael; Cuisset, Arnaud; Bocquet, Robin; Lampin, Jean-François; Blary, Karine; Peytavit, Emilien; Akalin, Tahsin; Ducournau, Guillaume

    2009-01-01

    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. PMID:22291552

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

    Science.gov (United States)

    Kozuki, Kohei; Nagashima, Takeshi; Hangyo, Masanori

    2011-12-05

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

  18. Electron energy-loss spectroscopy study of NiTi shape memory alloys

    International Nuclear Information System (INIS)

    Yang, Z.Q.; Schryvers, D.

    2008-01-01

    Electron energy loss spectroscopy (EELS) investigations were carried out on NiTi shape memory alloys. The composition of lens-shaped precipitates is determined to be Ni 4 Ti 3 by model-based EELS quantification, and the Ni-depleted zone in the B2 matrix surrounding the Ni 4 Ti 3 precipitates was quantified. The Young's modulus Y m of the B2 matrix with 51 at.% Ni and the Ni 4 Ti 3 precipitates was evaluated to be about 124 and 175 GPa, respectively. The intensity of the Ni L 3 edge for the precipitate is slightly higher than that for the B2 phase

  19. Conversion electron Moessbauer spectroscopy of plasma immersion ion implanted H13 tool steel

    International Nuclear Information System (INIS)

    Terwagne, G.; Hutchings, R.

    1994-01-01

    Conversion electron Moessbauer spectroscopy (CEMS) has been used to investigate nitride formation in AISI-H13 tool steel after treatment by plasma immersion ion implantation (PI 3 ) at 350 C. With only slight variation in the plasma conditions, it is possible to influence the kinetics of nitride precipitation so as to obtain nitrogen concentrations that range from those associated with ε-Fe 2 N through ε-Fe 3 N to γ'-Fe 4 N. The CEMS results enable a more definite identification of the nitrides than that obtained by glancing-angle X-ray diffraction and nuclear reaction analysis alone. (orig.)

  20. Conversion electron Mössbauer spectroscopy of plasma immersion ion implanted H13 tool steel

    Science.gov (United States)

    Terwagne, G.; Collins, G. A.; Hutchings, R.

    1994-12-01

    Conversion electron Mössbauer spectroscopy (CEMS) has been used to investigate nitride formation in AISI-H13 tool steel after treatment by plasma immersion ion implantation (PI3) at 350 °C. With only slight variation in the plasma conditions, it is possible to influence the kinetics of nitride precipitation so as to obtain nitrogen concentrations that range from those associated with ɛ-Fe2N through ɛ-Fe3N to γ'-Fe4N. The CEMS results enable a more definite identification of the nitrides than that obtained by glancing-angle X-ray diffraction and nuclear reaction analysis alone.

  1. Strong overtones modes in inelastic electron tunneling spectroscopy with cross-conjugated molecules

    DEFF Research Database (Denmark)

    Jørgensen, Jacob Lykkebo; Gagliardi, Alessio; Pecchia, Alessandro

    2013-01-01

    . With this in mind, we investigate a spectroscopic method capable of providing insight into these junctions for cross-conjugated molecules: inelastic electron tunneling spectroscopy (IETS). IETS has the advantage that the molecule interface is probed directly by the tunneling current. Previously, it has been thought...... and leading to suppressed levels of elastic current. In most theoretical studies, only the elastic contributions to the current are taken into account. In this paper, we study the inelastic contributions to the current in cross-conjugated molecules and find that while the inelastic contribution to the current...

  2. Probing Intermolecular Electron Delocalization in Dimer Radical Anions by Vibrational Spectroscopy

    International Nuclear Information System (INIS)

    Mani, Tomoyasu; Brookhaven National Laboratory; Grills, David C.

    2017-01-01

    Delocalization of charges is one of the factors controlling charge transport in conjugated molecules. It is considered to play an important role in the performance of a wide range of molecular technologies, including organic solar cells and organic electronics. Dimerization reactions are well-suited as a model to investigate intermolecular spatial delocalization of charges. And while dimerization reactions of radical cations are well investigated, studies on radical anions are still scarce. Upon dimerization of radical anions with neutral counterparts, an electron is considered to delocalize over the two molecules. By using time-resolved infrared (TRIR) detection coupled with pulse radiolysis, we show that radical anions of 4-n-hexyl-4'-cyanobiphenyl (6CB) undergo such dimerization reactions, with an electron equally delocalized over the two molecules. We have recently demonstrated that nitrile ν(C≡N) vibrations respond to the degree of electron localization of nitrile-substituted anions: we can quantify the changes in the electronic charges from the neutral to the anion states in the nitriles by monitoring the ν(C≡N) IR shifts. In the first part of this article, we show that the sensitivity of the ν(C≡N) IR shifts does not depend on solvent polarity. In the second part, we describe how probing the shifts of the nitrile IR vibrational band unambiguously confirms the formation of dimer radical anions, with K dim = 3 × 10 4 M –1 . IR findings are corroborated by electronic absorption spectroscopy and electronic structure calculations. We find that the presence of a hexyl chain and the formation of π–π interactions are both crucial for dimerization of radical anions of 6CB with neutral 6CB. Our study provides clear evidence of spatial delocalization of electrons over two molecular fragments.

  3. Optical and mechanical design for 1 nm resolution Auger spectroscopy in an electron microscope

    International Nuclear Information System (INIS)

    Bleeker, A.J.

    1991-01-01

    Detailed information about the atomic structure of surfaces and interfaces is vital for the progress in materials science and physics. One widely used surface sensitive technique is Auger spectroscopy (AS). This technique, in which the electron energy spectrum emerging from the sample is evaluated, gives information about the average elemental composition of the surface over a relative large surface area (>30nm). Electron microscopy (EM), on the other hand, is capable of producing surface structural, but no elemental, information with almost atomic resolution. EM and AS techniques have not been combined so far because of the different nature of the instrumentation used in both techniques. In AS instruments the sample is placed in an Ultra High Vacuum (UHV) system with a relatively large open space around the sample. In EM the sample is situated in the tight volume between the magnetic polepieces of the probe forming objective lens. The space around the sample is therefore tight. Furthermore the vacuum in most electron microscopes is not in UHV range. Radical mechanical changes to improve the vacuum are necessary to do AS in an electron microscope. Since the sample is immersed in the strong magnetic field of the objective lens the Auger electrons can not be extracted with conventional electrostatical methods. The only possibility to extract the Auger electrons is through the upper bore of the objective lens. However, this has large implications on the optical system of the microscope and requires a thorough investigation of the extraction of the Auger electrons. In this work it will be discussed how the surface sensitive AS can be combined with the high spatial resolution of the electron microscope in a practical instrument. (author). 102 refs.; 81 figs.; 4 tabs

  4. Detection of water and its derivatives on individual nanoparticles using vibrational electron energy-loss spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Crozier, Peter A., E-mail: crozier@asu.edu [School for the Engineering of Matter, Transport and Energy, Arizona State University, 501 E. Tyler Mall, Tempe, AZ 85287-6106 (United States); Aoki, Toshihiro [LeRoy Eyring Center for Solid State Science, Arizona State University, Tempe, AZ 85287-1704 (United States); Liu, Qianlang [School for the Engineering of Matter, Transport and Energy, Arizona State University, 501 E. Tyler Mall, Tempe, AZ 85287-6106 (United States)

    2016-10-15

    Understanding the role of water, hydrate and hydroxyl species on nanoparticle surfaces and interfaces is very important in both physical and life sciences. Detecting the presence of oxygen-hydrogen species with nanometer resolution is extremely challenging at present. Here we show that the recently developed vibrational electron energy-loss spectroscopy using subnanometer focused electron beams can be employed to spectroscopically identify the local presence and variation of OH species on nanoscale surfaces. The hydrogen-oxygen fingerprint can be correlated with highly localized structural and morphological information obtained from electron imaging. Moreover, the current approach exploits the aloof beam mode of spectral acquisition which does not require direct electron irradiation of the sample thus greatly reducing beam damage to the OH bond. These findings open the door for using electron microscopy to probe local hydroxyl and hydrate species on nanoscale organic and inorganic structures. - Highlights: • High spatial resolution spectroscopic detection of water related species in nanoparticles. • Detection of OH stretch modes with vibrational EELS. • Differentiation between hydrate and hydroxide species on or on nanoparticles. • Detection of hydrate on a single 60 nm oxide nanoparticle of MgO. • Use of aloof beam EELS to minimize radiation damage.

  5. Electronic structure of the L-cysteine films on dental alloys studied by ultraviolet photoelectron spectroscopy

    International Nuclear Information System (INIS)

    Ogawa, K; Takahashi, K; Azuma, J; Kamada, M; Tsujibayashi, T; Ichimiya, M

    2013-01-01

    The valence electronic structures of the dental alloys, type 1, type 3, K14, and MC12 and their interaction with L-cysteine have been studied by ultraviolet photoelectron spectroscopy with synchrotron radiation. It was found that the electronic structures of the type-1 and type-3 dental alloys are similar to that of polycrystalline Au, while that of the K14 dental alloy is much affected by Cu. The electronic states of the MC12 dental alloy originate dominantly from Cu 3d states and Pd 4d states around the top of the valence bands, while the 4∼7-eV electronic structure of MC12 originates from the Ag 4d states. The peak shift and the change in shape due to alloying are observed in all the dental alloys. For the L-cysteine thin films, new peak or structure observed around 2 eV on all the dental alloys is suggested to be due to the bonding of S 3sp orbitals with the dental alloy surfaces. The Cu-S bond as well as the Au-S and Au-O bonds may cause the change in the electronic structure of the L-cysteine on type 1, type 3 and K14. For MC12, the interaction with L-cysteine may be dominantly due to the Pd-S, Cu-S, and Ag-O bonds, while the contribution of the Ag-S bond is small.

  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. Electronic structure analysis of UO2 by X-ray absorption spectroscopy

    International Nuclear Information System (INIS)

    Ozkendir, O.M.

    2009-01-01

    Full text: Due to the essential role of Actinides in nuclear science and technology, electronic and structural investigations of actinide compounds attract major interest in science. Electronic structure of actinide compounds have important properties due to narrow 5f states which play key role in bonding with anions. The properties of Uranium has been a subject of enduring interest due to its being a major importance as a nuclear fuel and is the highest numbered element which can be found naturally on earth. UO 2 forms as a secondary uranyl group occurred during metamictization of uranium oxide compounds [1].Uranium oxide thin films have been investigated by X-ray Absorption Fine Structure spectroscopy (XAFS) [2]. The full multiple scattering approach has been applied to the calculation of U L3 edge spectra of UO 2 . The calculations are based on different choices of one electron potentials according to Uranium coordinations by using the real space multiple scattering method FEFF 8.2 code [3,4]. U L3-edge absorption spectrum in UO 2 is compared with U L3-edges in USiO 4 and UTe which are chosen due to their different electronic and chemical structures.We have found prominent changes in the XANES spectra of Uranium oxide thin films due to valency properties. Such observed changes are explained by considering the structural, electronic and spectroscopic properties. (author)

  8. Evidence of sequential interatomic decay in argon trimers obtained by electron-triple-ion coincidence spectroscopy

    International Nuclear Information System (INIS)

    Liu, X-J; Saito, N; Fukuzawa, H; Morishita, Y; Stoychev, S; Kuleff, A; Suzuki, I H; Tamenori, Y; Richter, R; Pruemper, G; Ueda, K

    2007-01-01

    Sequential interatomic decay, where the first step is an Auger decay with interatomic character and the second step is a pure interatomic Coulombic decay (ICD), is identified in Ar trimers Ar 3 . The 2p hole state in Ar 3 decays via the L 2,3 M 1 M 2,3 Auger to the one-site two-hole states Ar ++ (3s -1 3p -1 )-Ar-Ar that couples to the two-site satellite states Ar + (3p -2 nl)-Ar + (3p -1 )-Ar. These states are subject to ICD to the states Ar + (3p -1 )-Ar + (3p -1 )-Ar + (3p -1 ), in which the nl electron fills the 3p hole in the same Ar site and one of the 3p electrons in the third Ar site is emitted as a slow ICD electron. This ICD process is identified unambiguously by electron-ion-ion-ion coincidence spectroscopy in which the kinetic energy of the slow ICD electron and the kinetic energy release among the three Ar + ions are measured in coincidence. (fast track communication)

  9. Isotope effect on hydrated electron relaxation dynamics studied with time-resolved liquid jet photoelectron spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Elkins, Madeline H.; Williams, Holly L. [Department of Chemistry, University of California, Berkeley, California 94720 (United States); Neumark, Daniel M., E-mail: dneumark@berkeley.edu [Department of Chemistry, University of California, Berkeley, California 94720 (United States); Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

    2016-05-14

    The excited state relaxation dynamics of the solvated electron in H{sub 2}O and D{sub 2}O are investigated using time-resolved photoelectron spectroscopy in a liquid microjet. The data show that the initial excited state decays on a time scale of 75 ± 12 fs in H{sub 2}O and 102 ± 8 fs in D{sub 2}O, followed by slower relaxation on time scales of 400 ± 70 fs and 390 ± 70 fs that are isotopically invariant within the precision of our measurements. Based on the time evolution of the transient signals, the faster and slower time constants are assigned to p → s internal conversion (IC) of the hydrated electron and relaxation on the ground electronic state, respectively. This assignment is consistent with the non-adiabatic mechanism for relaxation of the hydrated electron and yields an isotope effect of 1.4 ± 0.2 for IC of the hydrated electron.

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

    Energy Technology Data Exchange (ETDEWEB)

    Colliex, Christian, E-mail: christian.colliex@u-psud.fr; Kociak, Mathieu; Stéphan, Odile

    2016-03-15

    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. 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

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

    International Nuclear Information System (INIS)

    Colliex, Christian; Kociak, Mathieu; Stéphan, Odile

    2016-01-01

    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

  13. Study of photo-activated electron transfer reactions in the first excited singlet state by picosecond and nanosecond laser spectroscopy

    International Nuclear Information System (INIS)

    Doizi, Denis

    1983-01-01

    Picosecond laser spectroscopy has been used to study two photo-activated electron transfer reactions: - a bimolecular electron transfer reaction between a sensitizer, DODCI, and an electron acceptor, methylviologen. The two radical ions created with an electron transfer efficiency γ ≅ 0.07 have been identified in picosecond and nanosecond laser absorption spectroscopy by adding selective solutes such as para-benzoquinone (an electron acceptor) or L(+) ascorbic acid (an electron donor). - an intramolecular electron transfer reaction in a triad molecule consisting of a tetra-aryl-porphyrin covalently linked to both a carotenoid and a quinone. The photoinduced charge separation occurs within 30 ps and leads, with a yield of 25 pc, to the formation of a zwitterion whose half-life is 2.5 μs. The experimental results obtained in these two studies show an effective decrease in the recombination rate of the two radical ions created in the encounter pair. (author) [fr

  14. Hybridized electronic states in potassium-doped picene probed by soft x-ray spectroscopies

    Directory of Open Access Journals (Sweden)

    Hiroyuki Yamane

    2012-12-01

    Full Text Available The electronic structure of the unoccupied and occupied states of potassium (K-doped and undoped picene crystalline films has been investigated by using the element-selective and bulk-sensitive photon-detection methods of X-ray absorption and emission spectroscopies. We observed the formation of the doping-induced unoccupied and occupied electronic states in K-doped picene. By applying the inner-shell resonant-excitation experiments, we observed the evidence for the orbital hybridization between K and picene near the Fermi energy. Furthermore, the resonant X-ray emission experiment suggests the presence of the Raman-active vibronic interaction in K-doped picene. These experimental evidences play a crucial role in the superconductivity of K-doped picene.

  15. Note: Microelectrode-shielding tip for scanning probe electron energy spectroscopy

    Science.gov (United States)

    Huang, Wei; Li, Zhean; Xu, Chunkai; Liu, Jian; Xu, Chunye; Chen, Xiangjun

    2018-04-01

    We report a novel microelectrode-shielding tip (ME tip) for scanning probe electron energy spectroscopy (SPEES). The shielding effect of this tip is studied through comparing the detection efficiency with the normal tip by both experiment and simulation. The results show that the backscattering count rate detected by the SPEES instrument using the normal tip begins to decrease as the tip approaches to the sample surface within 21 μm, while that using the ME tip only starts to drop off within 1 μm. This indicates that the electron energy spectra can be measured with the ME tip at a much closer tip-sample distance. Furthermore, it is also demonstrated that the ME tip can be used to obtain topography of the sample surface in situ simultaneously.

  16. Study of surface segregation of Si on palladium silicide using Auger electron spectroscopy

    International Nuclear Information System (INIS)

    Abhaya, S; Amarendra, G; Gopalan, Padma; Reddy, G L N; Saroja, S

    2004-01-01

    The transformation of Pd/Si to Pd 2 Si/Si is studied using Auger electron spectroscopy over a wide temperature range of 370-1020 K. The Pd film gets totally converted to Pd 2 Si upon annealing at 520 K, and beyond 570 K, Si starts segregating on the surface of silicide. It is found that the presence of surface oxygen influences the segregation of Si. The time evolution study of Si segregation reveals that segregation kinetics is very fast and the segregated Si concentration increases as the temperature is increased. Scanning electron microscopy measurements show that Pd 2 Si is formed in the form of islands, which grow as the annealing temperature is increased

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

    KAUST Repository

    Tizei, Luiz H. G.; Lin, Yung-Chang; Lu, Ang-Yd; Li, Lain-Jong; Suenaga, Kazu

    2016-01-01

    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.

  18. 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.

  19. Electronic structure of pentacene on hafnium studied by ultraviolet photoelectron spectroscopy

    International Nuclear Information System (INIS)

    Kang, Seong Jun; Yi, Yeon Jin; Kim, Chung Yi; Whang, Chung Nam

    2005-01-01

    The electronic structure of pentacene on hafnium, which is a low work function metal, was analyzed by using ultraviolet photoelectron spectroscopy. The energy level alignment was studied by using the onset of the highest occupied molecular orbital level and the shift of the vacuum level of the pentacene layer, which was deposited on a clean hafnium surface in a stepwise manner. The measured onset of the highest occupied molecular orbital energy level was 1.52 eV from the Fermi level of hafnium. The vacuum level was shifted 0.28 eV toward higher binding energy with additional pentacene layers, which means an interfacial dipole exists at the interface between pentacene and hafnium. We confirm that a small electron injection barrier can be achieved by inserting a low work function metal in a pentacene thin-film transistor.

  20. Electrochemistry and electron paramagnetic resonance spectroscopy of cytochrome c and its heme-disrupted analogs.

    Science.gov (United States)

    Novak, David; Mojovic, Milos; Pavicevic, Aleksandra; Zatloukalova, Martina; Hernychova, Lenka; Bartosik, Martin; Vacek, Jan

    2018-02-01

    Cytochrome c (cyt c) is one of the most studied conjugated proteins due to its electron-transfer properties and ability to regulate the processes involved in homeostasis or apoptosis. Here we report an electrochemical strategy for investigating the electroactivity of cyt c and its analogs with a disrupted heme moiety, i.e. apocytochrome c (acyt c) and porphyrin cytochrome c (pcyt c). The electrochemical data are supplemented with low-temperature and spin-probe electron paramagnetic resonance (EPR) spectroscopy. The main contribution of this report is a complex evaluation of cyt c reduction and oxidation at the level of surface-localized amino acid residues and the heme moiety in a single electrochemical scan. The electrochemical pattern of cyt c is substantially different to both analogs acyt c and pcyt c, which could be applicable in further studies on the redox properties and structural stability of cytochromes and other hemeproteins. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Characterisation of β-tricalcium phosphate-based bone substitute materials by electron paramagnetic resonance spectroscopy

    Science.gov (United States)

    Matković, Ivo; Maltar-Strmečki, Nadica; Babić-Ivančić, Vesna; Dutour Sikirić, Maja; Noethig-Laslo, Vesna

    2012-10-01

    β-TCP based materials are frequently used as dental implants. Due to their resorption in the body and direct contact with tissues, in order to inactivate bacteria, fungal spores and viruses, they are usually sterilized by γ-irradiation. However, the current literature provides little information about effects of the γ-irradiation on the formation and stability of the free radicals in the bone graft materials during and after sterilization procedure. In this work five different bone graft substitution materials, composed of synthetic beta tricalcium phosphate (β-TCP) and hydroxyapatite (HAP) present in the market were characterized by electron paramagnetic resonance (EPR) spectroscopy, X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). Paramagnetic species Mn2+, Fe3+, trapped H-atoms and CO2- radicals were detected in the biphasic material (60% HAP, 40% β-TCP), while in β-TCP materials only Mn2+ andor trapped hydrogen atoms were detected. EPR analysis revealed the details of the structure of these materials at the atomic level. The results have shown that EPR spectroscopy is a method which can be used to improve the quality control of bone graft materials after syntering, processing and sterilization procedure.

  2. Characterization of the calcification of cardiac valve bioprostheses by environmental scanning electron microscopy and vibrational spectroscopy.

    Science.gov (United States)

    Delogne, Christophe; Lawford, Patricia V; Habesch, Steven M; Carolan, Vikki A

    2007-10-01

    Bioprosthetic heart valve tissue and associated calcification were studied in their natural state, using environmental scanning electron microscopy (ESEM). Energy dispersive X-ray micro-analysis, X-ray diffraction, Fourier-transform infrared and Raman spectroscopy were used to characterize the various calcific deposits observed with ESEM. The major elements present in calcified valves were also analyzed by inductively coupled plasma-optical emission spectroscopy. To better understand the precursor formation of the calcific deposits, results from the elemental analyses were statistically correlated. ESEM revealed the presence of four broad types of calcium phosphate crystal morphology. In addition, two main patterns of organization of calcific deposits were observed associated with the collagen fibres. Energy dispersive X-ray micro-analysis identified the crystals observed by ESEM as salts containing mainly calcium and phosphate with ratios from 1.340 (possibly octacalcium phosphate, which has a Ca/P ratio of 1.336) to 2.045 (possibly hydroxyapatite with incorporation of carbonate and metal ion contaminants, such as silicon and magnesium, in the crystal lattice). Raman and fourier-transform infrared spectroscopy also identified the presence of carbonate and the analyses showed spectral features very similar to a crystalline hydroxyapatite spectrum, also refuting the presence of precursor phases such as beta-tricalcium phosphate, octacalcium phosphate and dicalcium phosphate dihydrate. The results of this study raised the possibility of the presence of precursor phases associated with the early stages of calcification.

  3. High-resolution monochromated electron energy-loss spectroscopy of organic photovoltaic materials.

    Science.gov (United States)

    Alexander, Jessica A; Scheltens, Frank J; Drummy, Lawrence F; Durstock, Michael F; Hage, Fredrik S; Ramasse, Quentin M; McComb, David W

    2017-09-01

    Advances in electron monochromator technology are providing opportunities for high energy resolution (10 - 200meV) electron energy-loss spectroscopy (EELS) to be performed in the scanning transmission electron microscope (STEM). The energy-loss near-edge structure in core-loss spectroscopy is often limited by core-hole lifetimes rather than the energy spread of the incident illumination. However, in the valence-loss region, the reduced width of the zero loss peak makes it possible to resolve clearly and unambiguously spectral features at very low energy-losses (photovoltaics (OPVs): poly(3-hexlythiophene) (P3HT), [6,6] phenyl-C 61 butyric acid methyl ester (PCBM), copper phthalocyanine (CuPc), and fullerene (C 60 ). Data was collected on two different monochromated instruments - a Nion UltraSTEM 100 MC 'HERMES' and a FEI Titan 3 60-300 Image-Corrected S/TEM - using energy resolutions (as defined by the zero loss peak full-width at half-maximum) of 35meV and 175meV, respectively. The data was acquired to allow deconvolution of plural scattering, and Kramers-Kronig analysis was utilized to extract the complex dielectric functions. The real and imaginary parts of the complex dielectric functions obtained from the two instruments were compared to evaluate if the enhanced resolution in the Nion provides new opto-electronic information for these organic materials. The differences between the spectra are discussed, and the implications for STEM-EELS studies of advanced materials are considered. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. a Study on SODIUM(110) and Other Nearly Free Electron Metals Using Angle Resolved Photoemission Spectroscopy.

    Science.gov (United States)

    Lyo, In-Whan

    Electronic properties of the epitaxially grown Na(110) film have been studied using angle resolved ultraviolet photoemission spectroscopy with synchrotron radiation as the light source. Na provides an ideal ground to study the fundamental aspects of the electron-electron interactions in metals, because of its simple Fermi surface and small pseudopotential. The absolute band structure of Na(110) using angle resolved photoemission spectroscopy has been mapped out using the extrema searching method. The advantage of this approach is that the usual assumption of the unoccupied state dispersion is not required. We have found that the dispersion of Na(1l0) is very close to the parabolic band with the effective mass 1.21 M_{rm e} at 90 K. Self-consistent calculations of the self-energy for the homogeneous electron gas have been performed using the Green's function technique within the framework of the GW approximation, in the hope of understanding the narrowing mechanism of the bandwidth observed for all the nearly-free-electron (NFE) metals. Good agreements between the experimental data and our calculated self-energy were obtained not only for our data on k-dependency from Na(l10), but also for the total bandwidth corrections for other NFE metals, only if dielectric functions beyond the random phase approximation were used. Our findings emphasize the importance of the screening by long wavelength plasmons. Off-normal spectra of angle resolved photoemission from Na(110) show strong asymmetry of the bulk peak intensity for the wide range of photon energies. Using a simple analysis, we show this asymmetry has an origin in the interference of the surface Umklapp electrons with the normal electrons. We have also performed the detailed experimental studies of the anomalous Fermi level structure observed in the forbidden gap region of Na. This was claimed by A. W. Overhauser as the evidence of the charge density wave in the alkali metal. The possibility of this hypothesis is

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

    CERN Document Server

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

    2013-01-01

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

  6. 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.

  7. Photoelectron-Auger electron coincidence spectroscopy of free molecules: New experiments

    International Nuclear Information System (INIS)

    Ulrich, Volker; Barth, Silko; Lischke, Toralf; Joshi, Sanjeev; Arion, Tiberiu; Mucke, Melanie; Foerstel, Marko; Bradshaw, Alex M.; Hergenhahn, Uwe

    2011-01-01

    Photoelectron-Auger electron coincidence spectroscopy probes the dicationic states produced by Auger decay following the photoionization of core or inner valence levels in atoms, molecules or clusters. Moreover, the technique provides valuable insight into the dynamics of core hole decay. This paper serves the dual purpose of demonstrating the additional information obtained by this technique compared to Auger spectroscopy alone as well as of describing the new IPP/FHI apparatus at the BESSY II synchrotron radiation source. The distinguishing feature of the latter is the capability to record both the photoelectron and Auger electron with good energy and angle resolution, for which purpose a large hemispherical electrostatic analyser is combined with several linear time-of-flight spectrometers. New results are reported for the K-shell photoionization of oxygen (O 2 ) and the subsequent KVV Auger decay. Calculations in the literature for non-coincident O 2 Auger spectra are found to be in moderately good agreement with the new data.

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

    Science.gov (United States)

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

    2014-10-01

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

  9. 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.

  10. Excitation transfer and trapping kinetics in plant photosystem I probed by two-dimensional electronic spectroscopy.

    Science.gov (United States)

    Akhtar, Parveen; Zhang, Cheng; Liu, Zhengtang; Tan, Howe-Siang; Lambrev, Petar H

    2018-03-01

    Photosystem I is a robust and highly efficient biological solar engine. Its capacity to utilize virtually every absorbed photon's energy in a photochemical reaction generates great interest in the kinetics and mechanisms of excitation energy transfer and charge separation. In this work, we have employed room-temperature coherent two-dimensional electronic spectroscopy and time-resolved fluorescence spectroscopy to follow exciton equilibration and excitation trapping in intact Photosystem I complexes as well as core complexes isolated from Pisum sativum. We performed two-dimensional electronic spectroscopy measurements with low excitation pulse energies to record excited-state kinetics free from singlet-singlet annihilation. Global lifetime analysis resolved energy transfer and trapping lifetimes closely matches the time-correlated single-photon counting data. Exciton energy equilibration in the core antenna occurred on a timescale of 0.5 ps. We further observed spectral equilibration component in the core complex with a 3-4 ps lifetime between the bulk Chl states and a state absorbing at 700 nm. Trapping in the core complex occurred with a 20 ps lifetime, which in the supercomplex split into two lifetimes, 16 ps and 67-75 ps. The experimental data could be modelled with two alternative models resulting in equally good fits-a transfer-to-trap-limited model and a trap-limited model. However, the former model is only possible if the 3-4 ps component is ascribed to equilibration with a "red" core antenna pool absorbing at 700 nm. Conversely, if these low-energy states are identified with the P 700 reaction centre, the transfer-to-trap-model is ruled out in favour of a trap-limited model.

  11. Direct Detection Electron Energy-Loss Spectroscopy: A Method to Push the Limits of Resolution and Sensitivity.

    Science.gov (United States)

    Hart, James L; Lang, Andrew C; Leff, Asher C; Longo, Paolo; Trevor, Colin; Twesten, Ray D; Taheri, Mitra L

    2017-08-15

    In many cases, electron counting with direct detection sensors offers improved resolution, lower noise, and higher pixel density compared to conventional, indirect detection sensors for electron microscopy applications. Direct detection technology has previously been utilized, with great success, for imaging and diffraction, but potential advantages for spectroscopy remain unexplored. Here we compare the performance of a direct detection sensor operated in counting mode and an indirect detection sensor (scintillator/fiber-optic/CCD) for electron energy-loss spectroscopy. Clear improvements in measured detective quantum efficiency and combined energy resolution/energy field-of-view are offered by counting mode direct detection, showing promise for efficient spectrum imaging, low-dose mapping of beam-sensitive specimens, trace element analysis, and time-resolved spectroscopy. Despite the limited counting rate imposed by the readout electronics, we show that both core-loss and low-loss spectral acquisition are practical. These developments will benefit biologists, chemists, physicists, and materials scientists alike.

  12. 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.

  13. Temperature Dependent Electron Transport Properties of Gold Nanoparticles and Composites: Scanning Tunneling Spectroscopy Investigations.

    Science.gov (United States)

    Patil, Sumati; Datar, Suwarna; Dharmadhikari, C V

    2018-03-01

    Scanning tunneling spectroscopy (STS) is used for investigating variations in electronic properties of gold nanoparticles (AuNPs) and its composite with urethane-methacrylate comb polymer (UMCP) as function of temperature. Films are prepared by drop casting AuNPs and UMCP in desired manner on silicon substrates. Samples are further analyzed for morphology under scanning electron microscopy (SEM) and atomic force microscopy (AFM). STS measurements performed in temperature range of 33 °C to 142 °C show systematic variation in current versus voltage (I-V) curves, exhibiting semiconducting to metallic transition/Schottky behavior for different samples, depending upon preparation method and as function of temperature. During current versus time (I-t) measurement for AuNPs, random telegraphic noise is observed at room temperature. Random switching of tunneling current between two discrete levels is observed for this sample. Power spectra derived from I-t show 1/f2 dependence. Statistical analysis of fluctuations shows exponential behavior with time width τ ≈ 7 ms. Local density of states (LDOS) plots derived from I-V curves of each sample show systematic shift in valance/conduction band edge towards/away from Fermi level, with respect to increase in temperature. Schottky emission is best fitted electron emission mechanism for all samples over certain range of bias voltage. Schottky plots are used to calculate barrier heights and temperature dependent measurements helped in measuring activation energies for electron transport in all samples.

  14. Measurement of Auger electron energies and intensities from muonic transitions in silver

    International Nuclear Information System (INIS)

    Callies, R.; Daniel, H.; Egidy, T. von; Hagn, H.; Hartmann, F.J.; Neumann, W.

    1983-01-01

    There is now general agreement that Coulomb capture of mesonic particles and deexcitation of the formed exotic atom must be accompanied by Auger electron emission. Auger electrons from a thin silver foil were counted by Si-pn-junction detectors with an extraordinarily thin dead layer. Lines could be resolved and intensity ratios determined. Two types of experiments were performed simultaneously, (I) with the slow-muon telescope in coincidence with any e - detector of the array and (II) as above but with an additional Ag X-ray coincidence from a Ge(Li) detector placed close to the target. (Auth.)

  15. Electrochemical impedance spectroscopy for study of electronic structure in disordered organic semiconductors—Possibilities and limitations

    Science.gov (United States)

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

    2018-04-01

    There is potential in applying conjugated polymers in novel organic optoelectronic devices, where a comprehensive understanding of the fundamental processes and energetics involved during transport and recombination is still lacking, limiting further device optimization. The electronic transport modeling and its optimization need the energy distribution of transport and defect states, expressed by the energy distribution of the Density of States (DOS) function, as input/comparative parameters. We present the Energy Resolved-Electrochemical Impedance Spectroscopy (ER-EIS) method for the study of transport and defect electronic states in organic materials. The method allows mapping over unprecedentedly wide energy and DOS ranges. The ER-EIS spectroscopic method is based on the small signal interaction between the surface of the organic film and the liquid electrolyte containing reduction-oxidation (redox) species, which is similar to the extraction of an electron by an acceptor and capture of an electron by a donor at a semiconductor surface. The desired DOS of electronic transport and defect states can be derived directly from the measured redox response signal to the small voltage perturbation at the instantaneous position of the Fermi energy, given by the externally applied voltage. The theory of the ER-EIS method and conditions for its validity for solid polymers are presented in detail. We choose four case studies on poly(3-hexylthiophene-2,5-diyl) and poly[methyl(phenyl)silane] to show the possibilities of the method to investigate the electronic structure expressed by DOS of polymers with a high resolution of about 6 orders of magnitude and in a wide energy range of 6 eV.

  16. Optimization of transversal relaxation of nitroxides for pulsed electron-electron double resonance spectroscopy in phospholipid membranes.

    Science.gov (United States)

    Dastvan, Reza; Bode, Bela E; Karuppiah, Muruga Poopathi Raja; Marko, Andriy; Lyubenova, Sevdalina; Schwalbe, Harald; Prisner, Thomas F

    2010-10-28

    Pulsed electron-electron double resonance (PELDOR) spectroscopy is increasingly applied to spin-labeled membrane proteins. However, after reconstitution into liposomes, spin labels often exhibit a much faster transversal relaxation (T(m)) than in detergent micelles, thus limiting application of the method in lipid bilayers. In this study, the main reasons for enhanced transversal relaxation in phospholipid membranes were investigated systematically by use of spin-labeled derivatives of stearic acid and phosphatidylcholine as well as spin-labeled derivatives of the channel-forming peptide gramicidin A under the conditions typically employed for PELDOR distance measurements. Our results clearly show that dephasing due to instantaneous diffusion that depends on dipolar interaction among electron spins is an important contributor to the fast echo decay in cases of high local concentrations of spin labels in membranes. The main difference between spin labels in detergent micelles and membranes is their local concentration. Consequently, avoiding spin clustering and suppressing instantaneous diffusion is the key step for maximizing PELDOR sensitivity in lipid membranes. Even though proton spin diffusion is an important relaxation mechanism, only in samples of low local concentrations does deuteration of acyl chains and buffer significantly prolong T(m). In these cases, values of up to 7 μs have been achieved. Furthermore, our study revealed that membrane composition and labeling position in the membrane can also affect T(m), either by promoting the segregation of spin-labeled species or by altering their exposure to matrix protons. Effects of other experimental parameters including temperature (<50 K), presence of oxygen, and cryoprotectant type are negligible under our experimental conditions.

  17. Electronic structure and thermal decomposition of 5-aminotetrazole studied by UV photoelectron spectroscopy and theoretical calculations

    Energy Technology Data Exchange (ETDEWEB)

    Pinto, Rui M., E-mail: ruipinto@fct.unl.pt [CFA, Centro de Fisica Atomica, Departamento de Fisica, Faculdade de Ciencias e Tecnologia, FCT, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Dias, Antonio A.; Costa, Maria L. [CFA, Centro de Fisica Atomica, Departamento de Fisica, Faculdade de Ciencias e Tecnologia, FCT, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal)

    2011-03-18

    Graphical abstract: Gas-phase UV photoelectron spectrum of the thermal decomposition of 5-aminotetrazole (5ATZ), obtained at 245 {sup o}C, and mechanism underlying the thermal dissociation of 2H-5ATZ. Research highlights: {yields} Electronic structure of 5ATZ studied by photoelectron spectroscopy. {yields} Gas-phase 5-ATZ exists mainly as the 2H-tautomer. {yields} Thermal decomposition of 5ATZ gives N{sub 2}, NH{sub 2}CN, HN{sub 3} and HCN, at 245 {sup o}C. {yields} HCN can be originated from a carbene intermediate. - Abstract: The electronic properties and thermal decomposition of 5-aminotetrazole (5ATZ) are investigated using UV photoelectron spectroscopy (UVPES) and theoretical calculations. Simulated spectra of both 1H- and 2H-5ATZ, based on electron propagator methods, are produced in order to study the relative gas-phase tautomer population. The thermal decomposition results are rationalized in terms of intrinsic reaction coordinate (IRC) calculations. 5ATZ yields a HOMO ionization energy of 9.44 {+-} 0.04 eV and the gas-phase 5ATZ assumes mainly the 2H-form. The thermal decomposition of 5ATZ leads to the formation of N{sub 2}, HN{sub 3} and NH{sub 2}CN as the primary products, and HCN from the decomposition of a intermediate CH{sub 3}N{sub 3} compound. The reaction barriers for the formation of HN{sub 3} and N{sub 2} from 2H-5ATZ are predicted to be {approx}228 and {approx}150 kJ/mol, at the G2(MP2) level, respectively. The formation of HCN and HNNH from the thermal decomposition of a CH{sub 3}N{sub 3} carbene intermediate is also investigated.

  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. Graphene oxide and reduced graphene oxide studied by the XRD, TEM and electron spectroscopy methods

    International Nuclear Information System (INIS)

    Stobinski, L.; Lesiak, B.; Malolepszy, A.; Mazurkiewicz, M.; Mierzwa, B.; Zemek, J.; Jiricek, P.; Bieloshapka, I.

    2014-01-01

    Highlights: • Graphene oxide (FL-GOc) and reduced graphene oxide (FL-RGOc): XRD, TEM, XPS, REELS. • FL-GOc: stacking nanostructure—22 × 6 nm (DxH), 0.9 nm layers separation (XRD). • FL-RGOc: stacking nanostructure—8 × 1 nm (DxH), 0.4 nm layers separation (XRD). • Reduction: oxygen group degradation, decreasing distance between graphene layers. • Number of graphene layers in stacking nanostructure: 6–7 (FL-GOc), 2–3 (FL-RGOc). - Abstract: The commercial and synthesised few-layer graphene oxide, prepared using oxidation reactions, and few-layer reduced graphene oxide samples were structurally and chemically investigated by the X-ray diffraction (XRD), transmission electron microscopy (TEM) and electron spectroscopy methods, i.e. X-ray photoelectron spectroscopy (XPS) and reflection electron energy loss spectroscopy (REELS). The commercial graphene oxide (FL-GOc) shows a stacking nanostructure of about 22 × 6 nm average diameter by height with the distance of 0.9 nm between 6-7 graphene layers, whereas the respective reduced graphene oxide (FL-RGOc)—about 8 × 1 nm average diameter by height stacking nanostructure with the distance of 0.4 nm between 2-3 graphene layers (XRD). The REELS results are consistent with those by the XRD indicating 8 (FL-GOc) and 4 layers (FL-RGOc). In graphene oxide and reduced graphene oxide prepared from the graphite the REELS indicates 8–11 and 7–10 layers. All graphene oxide samples show the C/O ratio of 2.1–2.3, 26.5–32.1 at% of C sp 3 bonds and high content of functional oxygen groups (hydroxyl—C-OH, epoxy—C-O-C, carbonyl—C=O, carboxyl—C-OOH, water) (XPS). Reduction increases the C/O ratio to 2.8–10.3, decreases C sp 3 content to 11.4–20.3 at% and also the content of C-O-C and C=O groups, accompanied by increasing content of C-OH and C-OOH groups. Formation of additional amount of water due to functional oxygen group reduction leads to layer delamination. Removing of functional oxygen groups

  20. Characterization of the electronic structure of C50Cl10 by means of soft x-ray spectroscopies

    International Nuclear Information System (INIS)

    Brena, Barbara; Luo Yi

    2005-01-01

    The electronic structure of the last synthesized fullerene molecule, the C 50 Cl 10 , has been characterized by theoretical simulation of x-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy, and near-edge x-ray-absorption fine structure. All the calculations were performed at the gradient-corrected and hybrid density-functional theory levels. The combination of these techniques provides detailed information about the valence band and the unoccupied molecular orbitals, as well as about the carbon core orbitals

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

    International Nuclear Information System (INIS)

    Yang, D.J.; Zhang, J.D.; Leung, J.K.C.; Beling, C.D.; Liu, L.B.

    2006-01-01

    Full text: To understand the electron irradiation effects on polymer, polyether-urethane (ETPU) samples of 2m m in thickness and 1 0 m m in diameter were irradiated by a 1.8M eV 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 15 x1 0 3m οc 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

  2. Remarks on some reference materials for applications in elastic peak electron spectroscopy

    International Nuclear Information System (INIS)

    Jablonski, A.; Zemek, J.

    2010-01-01

    The quantification of results of electron spectroscopies, AES and XPS, requires knowledge of the inelastic mean free path (IMFP) of signal electrons in solids. This parameter determines the surface sensitivity of both techniques. There are two methods of determining the IMFPs that provide these parameters in agreement with the definition: (1) calculations based on the experimental optical data, and (2) calculations based on measurements of the electron elastic backscattering intensity. The latter method requires the use of some reference material for which the IMFP is known. In 1999, an extensive analysis of the published IMFPs has been performed; the results indicated that there is a very good agreement between the calculated and measured IMFPs for four elemental solids: Ni, Cu, Ag and Au. The averaged IMFPs for these elements are known under the name of the recommended IMFPs. However, no preference among these four elements has been established. In the present work, an attempt is made to select an element for which the recommended IMFPs result in the best agreement between the calculated and measured intensities of elastic electron backscattering. For this purpose, the elastic backscattering intensity has been measured at eight electron energies varying from 200 to 1500 eV. At each energy, the intensity was measured over a wide range of emission angles from 35deg to 74deg. The experiments were accompanied with Monte Carlo calculations of the elastic backscattering probability for the same energies and experimental configurations. It has been found, from comparison, that the best agreement is observed for Au, and this element is thus recommended as the reference material. It has been shown that the shape of the emission angle dependence of the elastic backscattering intensity is noticeably influenced by the surface energy losses. (author)

  3. Development and testing of a fast digital electronic system for ion identification and spectroscopy

    International Nuclear Information System (INIS)

    Legou, Th.

    2002-02-01

    This report deals with a fast digital electronic system developed for ion identification and spectroscopy. The system, called IRIS, has been conceived for the super heavy element research program: FUSION. In order to observe a super heavy element, the energy of the compound nucleus implanted in a silicon detector must be measured, and the alpha decay also registered. The associated electronics must therefore handle a very wide range of energies and also exhibit a small recovery time after the implantation of the compound nucleus. IRIS is connected to the output of a charge preamplifier. It digitizes the signal and then executes two digital signal processes: the first to detect the particle, and the second to determine the energy deposited in the silicon detector. The use of programmed processing allows for the adjustment of the digital processing parameters, as well as a choice of other digital signal processing procedures, depending the application. After having explained why a conventional electronic system cannot be used for the detection of super-heavy ions, IRIS' structure is detailed and a number of digital signal processing procedures are studied and tested. (author)

  4. Interaction of multicharged ions with molecules (CO2, C60) by coincident electron spectroscopy

    International Nuclear Information System (INIS)

    Moretto-Capelle, P.; Bordenave-Montesquieu, D.; Bordenave-Montesquieu, A.

    2001-01-01

    First results for the investigation of electron capture processes in collisions between multicharged ions and molecule targets using electron spectroscopy in coincidence with charged fragments, are presented. It is shown that a much more detailed investigation of the capture reaction can be achieved using molecular instead of heavy atomic targets provided that an analysis of the target dissociation is made. The collisional systems 18 O 8+ +Ar, CO 2 and C 60 have been studied at 80 keV. Non coincident electron spectra as well as first results of double or triple coincidence experiments are discussed. Kinetic energy distributions of the C n + fragments (n=1 to 8) produced in multiple capture processes from C 60 target are given. A detailed investigation of the double capture process with CO 2 molecule allows the measurement of kinetic energy release distributions (KERD) which characterize the dissociation of CO 2 2+ molecular ions; our results are found to be very similar to those measured in double photoionisation experiments. (orig.)

  5. 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.

  6. Scanning photoelectron microscope for nanoscale three-dimensional spatial-resolved electron spectroscopy for chemical analysis.

    Science.gov (United States)

    Horiba, K; Nakamura, Y; Nagamura, N; Toyoda, S; Kumigashira, H; Oshima, M; Amemiya, K; Senba, Y; Ohashi, H

    2011-11-01

    In order to achieve nondestructive observation of the three-dimensional spatially resolved electronic structure of solids, we have developed a scanning photoelectron microscope system with the capability of depth profiling in electron spectroscopy for chemical analysis (ESCA). We call this system 3D nano-ESCA. For focusing the x-ray, a Fresnel zone plate with a diameter of 200 μm and an outermost zone width of 35 nm is used. In order to obtain the angular dependence of the photoelectron spectra for the depth-profile analysis without rotating the sample, we adopted a modified VG Scienta R3000 analyzer with an acceptance angle of 60° as a high-resolution angle-resolved electron spectrometer. The system has been installed at the University-of-Tokyo Materials Science Outstation beamline, BL07LSU, at SPring-8. From the results of the line-scan profiles of the poly-Si/high-k gate patterns, we achieved a total spatial resolution better than 70 nm. The capability of our system for pinpoint depth-profile analysis and high-resolution chemical state analysis is demonstrated. © 2011 American Institute of Physics

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

    Science.gov (United States)

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

    2014-02-21

    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(N(c)) X(N(x)) (X = F or H). We studied GNFs with 10 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.

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

    Science.gov (United States)

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

    2006-04-20

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

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

    International Nuclear Information System (INIS)

    Nagatomi, T.; Goto, K.

    2010-01-01

    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. Electron momentum spectroscopy of the group I and Il metal and oxides

    International Nuclear Information System (INIS)

    Ford, M.J.; Dorsett, H.E.; Sashin, V.A.; Bolorizadeh, M.A.; Mikajlo, E.A.; Soule de Bas, B.; Nixon, K.L.; Coleman, V.A.

    2002-01-01

    Full text: The group I and Il metals and oxides are relatively simple condensed phase systems that are easily accessible to theoretical studies. For this reason they have been the subject of a number of studies using a range of theoretical techniques. Calculated electronic band structures have traditionally been compared with optical, X-ray and photo emissions measurements. While these techniques provide excellent data for testing theoretical predictions they generally probe certain aspects of the electronic structure, such as special point energies or densities of states, or require considerable theoretical input for their interpretation. In this paper we present our electron momentum spectroscopy (EMS) measurements for the lighter group Il metals and oxides and group I oxides. EMS can measure directly the full band dispersions and intensities and provides a sensitive test of theoretical predictions. We compare our measurements with Hartree-Fock (HF) and density functional theory (DFT) calculations carried out within the linear combination of atomic orbitals approximation. As expected HF significantly overestimates the bandwidths and bandgaps. DFT gives reasonable overall agreement, albeit with slight overestimation of bandwidths for the oxides. The intensity distribution for the oxides show a systematic difference from all the calculations which cannot easily be explained by experimental effects such as multiple scattering in the target. This work was funded by the Australian Research Council and Flinders University. EA Mikajlo and K L Nixon acknowledge receipt of SENRAC and Ferry scholarships respectively

  11. Infrared Multiphoton Dissociation Spectroscopy with Free-Electron Lasers: On the Road from Small Molecules to Biomolecules.

    Science.gov (United States)

    Jašíková, Lucie; Roithová, Jana

    2018-03-07

    Infrared multiphoton dissociation (IRMPD) spectroscopy is commonly used to determine the structure of isolated, mass-selected ions in the gas phase. This method has been widely used since it became available at free-electron laser (FEL) user facilities. Thus, in this Minireview, we examine the use of IRMPD/FEL spectroscopy for investigating ions derived from small molecules, metal complexes, organometallic compounds and biorelevant ions. Furthermore, we outline new applications of IRMPD spectroscopy to study biomolecules. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. BAND ALIGNMENT OF ULTRATHIN GIZO/SiO2/Si HETEROSTRUCTURE DETERMINED BY ELECTRON SPECTROSCOPY

    Directory of Open Access Journals (Sweden)

    Hee Jae Kang2

    2011-11-01

    Full Text Available Amorphous GaInZnO (GIZO thin films are grown on SiO2/Si substrate by the RF magnetron sputtering method. By thecombination of measured band gaps from reflection energy loss spectroscopy (REELS spectra and valence band fromX-ray photo-electron spectroscopy (XPS spectra, we have demonstrated the energy band alignment of GIZO thin films.The band gap values are 3.2 eV, 3.2 eV, 3.4eV and 3.6eV for the concentration ratios of Ga: In: Zn in GIZO thin filmsare 1:1:1, 2:2:1, 3:2:1 and 4:2:1, respectively. These are attributed to the larger band gap energy of Ga2O3 comparedwith In2O3 and ZnO. The valence band offsets (ΔEv decrease from 2.18 to 1.68 eV with increasing amount of Ga inGIZO thin films for GIZO1 to GIZO4, respectively. These experimental values of band gap and valence band offsetwill provide the further understanding in the fundamental properties of GIZO/SiO2/Si heterostructure, which will beuseful in the design, modeling and analysis of the performance devices applications.

  13. Addressing the electronic properties of III–V nanowires by photoluminescence excitation spectroscopy

    International Nuclear Information System (INIS)

    De Luca, M

    2017-01-01

    Semiconductor nanowires (NWs) have been attracting an increasing interest in the scientific community. This is due to their peculiar filamentary shape and nanoscale diameter, which renders them versatile and cost-effective components of novel technological devices and also makes them an ideal platform for the investigation of a variety of fascinating physical effects. Absorption spectroscopy is a powerful and non-destructive technique able to provide information on the physical properties of the NWs. However, standard absorption spectroscopy is hard to perform in NWs, because of their small volume and the presence of opaque substrates. Here, we demonstrate that absorption can be successfully replaced by photoluminescence excitation (PLE). First, the use of polarization-resolved PLE to address the complex and highly-debated electronic band structure of wurtzite GaAs and InP NWs is shown. Then, PLE is used as a statistically-relevant method to localize the presence of separate wurtzite and zincblende NWs in the same InP sample. Finally, a variety of resonant exotic effects in the density of states of In x Ga 1−x As/GaAs core/shell NWs are highlighted by high-resolution PLE. (paper)

  14. Contribution of Auger electron spectroscopy to study of mechanism of adhesive wear of valves

    International Nuclear Information System (INIS)

    Smrkovsky, E.; Koutnik, M.; Potmesilova, A.

    1987-01-01

    Briefly characterized are hypotheses describing the process of intensive adhesive wear (jamming) of materials on functional friction surfaces of valves. Two types of alloys were studied, 1Cr18Ni8Mo5Mn5Si5Nb and NiCrSiB. Auger electron spectroscopy was used in the study of the chemical composition of surface layers. The following conclusions can be made from the results of the adhesive wear measurement and the Auger spectroscopy measurement: There are oxide layers on the surfaces of the specimens which, however, can only to a certain extent affect the process of adhesive wear. Adhesive wear resistance tests using low hardness specimens show that in spite of the existence of oxide layers, friction pairs showing low surface hardness also feature low adhesive wear resistance. Following heat treatment, the surface oxide layers have practically the same chemical composition as the specimens without heat treatment. However, there adhesive wear resistance is significantly higher. (Z.M.). 3 tabs., 7 refs

  15. Dissociation mechanism of HNIW ions investigated by chemical ionization and electron impact mass spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Rongjie; Xiao, Hemiao [School of Materials Science and Engineering, Beijing Institute of Technology, Beijing 100081 (China)

    2006-04-15

    Chemical Ionization (CI) with Collision-Induced Dissociation (CID) spectroscopy and Electron Impacting (EI) with metastable Mass analyzed Ion Kinetic Energy (MIKE) spectroscopy have been applied to study ionic dissociations of Hexanitrohexaazaisowurtzitane (HNIW). Similarities and differences between EI/MIKE and CI/CID mass spectra of HNIW were analyzed. In EI mass spectra, the ions [HNIW-n NO{sub 2}]{sup +} (n=2-5), such as the ion at m/z 347, were less frequent (1-2% relative abundance), but in CI mass spectra, these ions were very abundant. For some ions of large molar mass from HNIW, their dissociations pathways from parent ions to daughter ions were built according to CID and MIKE spectra. Molecular ions of HNIW with a protonated nitro group at five-member ring seem more stable than at six-member ring. The HNIW ions losing five of six nitro groups are very stable based on CID spectra, which agrees with some research results for thermal decomposition of HNIW in literature. (Abstract Copyright [2006], Wiley Periodicals, Inc.)

  16. Energy-momentum structure of the krypton valence shell by electron-momentum spectroscopy

    International Nuclear Information System (INIS)

    Nicholson, R.; Braidwood, S.W.; McCathy, I.E.; Weigold, E.; Brunger, M.J.

    1996-03-01

    Momentum distributions and spectroscopic factors are obtained in a high resolution electron-momentum spectroscopy study of krypton at 1000 eV. The shapes and relative magnitudes of the momentum profiles are in good agreement with the results of calculations made within the distorted-wave impulse approximation (DWIA) framework. The DWIA describes the relative magnitudes of the 4p and 4s manifolds as well as giving a good representation of the shapes of the respective 4p and 4s cross sections. Results for the momentum profiles belonging to excited 2 P o and 2 S e manifolds are also presented. Spectroscopic factors for transitions belonging to the 2 p o and 2 S e manifolds are assigned up to a binding energy of 42 eV. The spectroscopic factor for the lowest 4s transition is 0.51 ± 0.01, whereas that for the ground-state 4p transition is 0.98± 0.01. Comparisons of the present binding energies and spectroscopic factors are made against the results of several many-body calculations and photoelectron spectroscopy (PES) results. In addition, a new procedure is outlined, utilising the experimental 4p and 4s manifold cross sections, that provides information on possible initial state configuration interaction effects in krypton. 50 refs., 2 tabs., 10 figs

  17. Microwave spectroscopy and electronic transport properties of ferromagnetic Josephson junctions and superconducting spin-valves

    Energy Technology Data Exchange (ETDEWEB)

    Thalmann, Marcel; Rudolf, Marcel; Pietsch, Torsten [Zukunftskolleg and Department of Physics, University of Konstanz, Universitaetsstrasse 10, 78464 Konstanz (Germany)

    2016-07-01

    Hybrid superconducting nanostructures recently attracted tremendous interest, due to their great potential in dissipation-less spin-electronics with unprecedented switching rates. The practical realisation of such devices, however, requires a complete understanding of the transfer and dynamics of spin- and charge currents between superconducting (S) and ferromagnetic (F) circuit elements, as well as the coupling between spin- and charge degrees of freedom in these systems. We investigate novel transport phenomena in superconductor-ferromagnet hybrid nanostructures under non-equilibrium conditions. Microwave spectroscopy is used to elucidate fundamental questions related to the complex interplay of competing order parameters and the question of relaxation mechanisms of non-equilibrium distributions with respect to spin, charge and energy. Recent experiments on two complimentary device structures are discussed: (I) in diffusive S/F/S Josephson junctions with non-sinusoidal current-phase relationship and (II) local and non-local transport measurements and microwave spectroscopy in F/S/F lateral spin-valves.

  18. Probing Nitrosyl Ligation of Surface-Confined Metalloporphyrins by Inelastic Electron Tunneling Spectroscopy

    Science.gov (United States)

    2013-01-01

    Complexes obtained by the ligation of nitric oxide (NO) to metalloporphyrins represent important model systems with biological relevance. Herein we report a molecular-level investigation of surface-confined cobalt tetraphenyl porphyrin (Co-TPP) species and their interaction with NO under ultrahigh vacuum conditions. It is demonstrated that individual NO adducts can be desorbed using the atomically sharp tip of a scanning tunneling microscope, whereby a writing process is implemented for fully saturated regular metalloporphyrin arrays. The low-energy vibrational characteristics of individual Co-TPP-nitrosyl complexes probed by inelastic electron tunneling spectroscopy (IETS) reveal a prominent signature at an energy of ≃31 meV. Using density functional theory-based IETS simulations—the first to be performed on such an extensive interfacial nanosystem—we succeed to reproduce the low-frequency spectrum for the NO-ligated complex and explain the absence of IETS activity for bare Co-TPP. Moreover, we can conclusively assign the IETS peak of NO-Co-TPP to a unique vibration mode involving the NO complexation site, namely, the in-plane Co–N–O rocking mode. In addition, we verify that the propensity rules previously designed on small aromatic systems and molecular fragments hold true for a metal–organic entity. This work notably permits one to envisage IETS spectroscopy as a sensitive tool to chemically characterize hybrid interfaces formed by complex metal–organic units and gaseous adducts. PMID:23718257

  19. Molecular electronics of a single photosystem I reaction center: Studies with scanning tunneling microscopy and spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Lee, I.; Lee, J.W.; Warmack, R.J.; Allison, D.P.; Greenbaum, E. [Oak Ridge National Lab., TN (United States)

    1995-03-14

    Thylakoids and photosystem I (PSI) reaction centers were imaged by scanning tunneling microscopy. The thylakoids were isolated from spinach chloroplasts, and PSI reaction centers were extracted from thylakoid membranes. Because thylakoids are relatively thick nonconductors, they were sputter-coated with Pd/Au before imaging. PSI photosynthetic centers and chemically platinized PSI were investigated without sputter-coating. They were mounted on flat gold substrates that had been treated with mercaptoacetic acid to help bind the proteins. With tunneling spectroscopy, the PSI centers displayed a semiconductor-like response with a band gap of 1.8 eV. Lightly platinized (platinized for 1 hr) centers displayed diode-like conduction that resulted in dramatic contrast changes between images taken with opposite bias voltages. The electronic properties of this system were stable under long-term storage. 42 refs., 7 figs.

  20. Detection of irradiated deboned turkey meat using electron spin resonance spectroscopy

    International Nuclear Information System (INIS)

    Gray, Richard; Stevenson, M.H.

    1989-01-01

    Bone fragments were extracted from two blocks of frozen deboned turkey meat (irradiated and non-irradiated) using alcoholic KOH digestion. Electron spin resonance (ESR) spectroscopy was used to differentiate between the samples. Comparison of an alcoholic KOH digestion procedure with a freeze drying and grinding method showed that the former method gave a signal which was 78% of that obtained using the freeze drying procedure. Regression analysis of the results obtained after subjection of the original non-irradiated sample to irradiation doses of 3.0, 5.0 and 7.0 kGy gave a linear relationship between irradiation dose and ESR signal strength over this range. Using this relationship the estimated mean dose received by the irradiated block was 4.72 kGy. (author)

  1. Comparison endpoint study of process plasma and secondary electron beam exciter optical emission spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Stephan Thamban, P. L.; Yun, Stuart; Padron-Wells, Gabriel; Hosch, Jimmy W.; Goeckner, Matthew J. [Department of Mechanical Engineering, University of Texas at Dallas, 800W Campbell Road, Richardson, Texas 75080 (United States); Department of Electrical Engineering, University of Texas at Dallas, 800W Campbell Road, Richardson, Texas 75080 (United States); Verity Instruments, Inc., 2901 Eisenhower Street, Carrollton, Texas 75007 (United States); Department of Mathematical Sciences, University of Texas at Dallas, 800 W Campbell Road, Richardson, Texas 75080 (United States)

    2012-11-15

    Traditionally process plasmas are often studied and monitored by optical emission spectroscopy. Here, the authors compare experimental measurements from a secondary electron beam excitation and direct process plasma excitation to discuss and illustrate its distinctiveness in the study of process plasmas. They present results that show excitations of etch process effluents in a SF{sub 6} discharge and endpoint detection capabilities in dark plasma process conditions. In SF{sub 6} discharges, a band around 300 nm, not visible in process emission, is observed and it can serve as a good indicator of etch product emission during polysilicon etches. Based on prior work reported in literature the authors believe this band is due to SiF{sub 4} gas phase species.

  2. Tip-induced local strain on Mo S2/graphite detected by inelastic electron tunneling spectroscopy

    Science.gov (United States)

    Ko, Wonhee; Hus, Saban M.; Li, Xufan; Berlijn, Tom; Nguyen, Giang D.; Xiao, Kai; Li, An-Ping

    2018-03-01

    We report the detection of tip-induced local strain applied to the monolayer Mo S2 grown on a graphite substrate by scanning tunneling microscope. Monolayer Mo S2 behaves as both mechanical and tunneling barriers that prevent the tip from contacting the graphite while maintaining the tunneling current. Inelastic tunneling electron spectroscopy (IETS) is utilized to probe the phonon modes in graphite. As the tip pushes the sample, IETS reveals a continuous phonon softening in graphite, corroborated by a downward shift of the phonon energy as calculated by density-functional theory. Our results demonstrate a way to apply local mechanical strain and simultaneously detect the induced change in phonon modes by unitizing IETS with two-dimensional materials as a tunneling barrier.

  3. Auger electron spectroscopy investigation of metallic fusible links in programmable read-only memories

    International Nuclear Information System (INIS)

    Morgan, A.E.; Quackenbush, T.R.; Lim, S.C.P.

    1983-01-01

    The composition of Ni-Cr, Ti-W and Ti-W-N thin film fuses as used in bipolar programmable read-only memories was studied using Auger electron spectroscopy. Measurements were performed on both intact and blown fuses in actual devices, and also on thin film samples processed so as to duplicate device fabrication. Topics of interest were (a) selection of film deposition technique, (b) minimization of contact resistance to aluminum, (c) promotion of good adhesion to SiO 2 , (d) avoidance of chemical attack during device production, (e) fuse corrosion in the finished product and (f) the fusing mechanism during device programming. The results are used to compare and contrast the behavior of the different types of fuses. From these studies, it appears that Ni-Cr could be beneficially replaced as the fuse material by Ti-W or Ti-W-N. (Auth.)

  4. Electron energy-loss spectroscopy of single nanocrystals: mapping of tin allotropes

    Science.gov (United States)

    Roesgaard, Søren; Ramasse, Quentin; Chevallier, Jacques; Fyhn, Mogens; Julsgaard, Brian

    2018-05-01

    Using monochromated electron energy-loss spectroscopy (EELS), we are able to map different allotropes in Sn-nanocrystals embedded in Si. It is demonstrated that α-Sn and β-Sn, as well as an interface related plasmon, can be distinguished in embedded Sn-nanostructures. The EELS data is interpreted by standard non-negative matrix factorization followed by a manual Lorentzian decomposition. The decomposition allows for a more physical understanding of the EELS mapping without reducing the level of information. Extending the analysis from a reference system to smaller nanocrystals demonstrates that allotrope determination in nanoscale systems down below 5 nm is possible. Such local information proves the use of monochromated EELS mapping as a powerful technique to study nanoscale systems. This possibility enables investigation of small nanostructures that cannot be investigated through other means, allowing for a better understanding and thus leading to realizations that can result in nanomaterials with improved properties.

  5. Gamma-Irradiated seafoods: identification and dosimetry by electron paramagnetic resonance spectroscopy

    International Nuclear Information System (INIS)

    Desrosiers, M.F.

    1989-01-01

    Electron paramagnetic resonance (EPR) spectroscopy was used to measure the production of free radicals induced by 60Co γ-rays in shrimp exoskeleton, mussel shells, and fish bones. The EPR spectrum for irradiated shrimp shell was dose dependent and appeared to be derived from more than one radical. The major component of the radiation-induced spectrum resulted from radical formation in chitin, assigned by comparison with irradiated N-acetyl-D-glucosamine. Other measurements include the total yield of radicals formed as a function of dose and the longevity of the radiation-induced EPR signal. Similar measurements were made for mussel shells and fish bones, and the results are compared and discussed. It was concluded that irradiated shrimp (with shell attached) could definitely be identified by this technique; however, precise determination of absorbed dose was less straightforward. Positive identification of irradiated fish bones was also clearly distinguishable, and dosimetry by EPR appeared to be feasible. (author)

  6. Imaging buried organic islands by spatially resolved ballistic electron emission spectroscopy

    International Nuclear Information System (INIS)

    Goh, Kuan Eng J; Bannani, A; Troadec, C

    2008-01-01

    The well-known Au/n-Si(111) Schottky interface is modified by a discontinuous pentacene film (∼1.5 nm thick) and studied using spatially resolved ballistic electron emission spectroscopy (BEES). The pentacene film introduced subtle changes to the interface which cannot be definitively detected by current-voltage measurements or a standard BEES analysis of the barrier height. In contrast, analyzing the BEES results in a dual-parameter (transmission attenuation and barrier height) space allows the effect of the pentacene film on the Au/n-Si(111) interface to be clearly demonstrated. We found that the pentacene film behaves like a tunneling barrier and increases the distribution of local barrier heights with a tendency toward lower values. Our results highlight the potential of the dual-parameter BEES analysis for understanding local interface modification by molecules.

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

    Science.gov (United States)

    Frisenda, Riccardo; Perrin, Mickael L; van der Zant, Herre S J

    2015-01-01

    We study single-molecule oligo(phenylene ethynylene)dithiol junctions by means of inelastic electron tunneling spectroscopy (IETS). The molecule is contacted with gold nano-electrodes formed with the mechanically controllable break junction technique. We record the IETS spectrum of the molecule from direct current measurements, both as a function of time and electrode separation. We find that for fixed electrode separation the molecule switches between various configurations, which are characterized by different IETS spectra. Similar variations in the IETS signal are observed during atomic rearrangements upon stretching of the molecular junction. Using quantum chemistry calculations, we identity some of the vibrational modes which constitute a chemical fingerprint of the molecule. In addition, changes can be attributed to rearrangements of the local molecular environment, in particular at the molecule-electrode interface. This study shows the importance of taking into account the interaction with the electrodes when describing inelastic contributions to transport through single-molecule junctions.

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

    DEFF Research Database (Denmark)

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

    2012-01-01

    the LSPR signal coming from the whole specimen, providing information complementary to the TEM analysis. During any ETEM experiment the electron beam effect on the sample is a difficult issue to address and rule out. In addition, if a reaction has to be followed in situ in the ETEM, the information...... is often recorded on a limited portion of the sample. Being able to probe the sample with INPS and ETEM at the same time allows parallel investigation at the local and macro scale, as well as aids the assessment of beam effects. A dedicated custom TEM specimen holder containing two optical fibers, five...... electrical contacts, a fixed miniaturized optical bench for light handling and a heating element (Fig. 1) has been designed. A system of pre-aligned mirrors and a MEMS heater are implemented in the holder. The system is primarily designed for use in combination with LSPR spectroscopy, but it is flexible...

  9. Quantitative detection of plasma-generated radicals in liquids by electron paramagnetic resonance spectroscopy

    International Nuclear Information System (INIS)

    Tresp, H; Hammer, M U; Winter, J; Reuter, S; Weltmann, K-D

    2013-01-01

    In this paper the qualitative and quantitative detection of oxygen radicals in liquids after plasma treatment with an atmospheric pressure argon plasma jet by electron paramagnetic resonance spectroscopy is investigated. Absolute values for · OH and O 2 ·- radical concentration and their net production rate in plasma-treated liquids are determined without the use of additional scavenging chemicals such as superoxide dismutase (SOD) or mannitol (D-MAN). The main oxygen-centred radical generation in PBS was found to originate from the superoxide radical. It is shown that hidden parameters such as the manufacturer of chemical components could have a big influence on the comparability and reproducibility of the results. Finally, the effect of a shielding gas device for the investigated plasma jet with a shielding gas composition of varying oxygen-to-nitrogen ratio on radical generation after plasma treatment of phosphate-buffered saline solution was investigated. (paper)

  10. Analysis of electron-irradiated poly-ether ether ketone by X-ray photoelectron spectroscopy

    International Nuclear Information System (INIS)

    Oyabu, Matashige; Kobayashi, Yoshinori; Seguchi, Tadao; Sasuga, Tsuneo; Kudoh, Hisaaki.

    1995-01-01

    Organic polymers used in atomic power plants or space are damaged by ionizing irradiation. Radicals produced by irradiation cause oxidation, chain scission and crosslinking, all of which lead to degradation of the material. In this paper, the surface of electron-irradiated poly-ether ether ketone (PEEK) was studied by X-ray photoelectron spectroscopy (XPS). The irradiation in air was found to oxidize the PEEK surface producing carboxyl groups, the content of which dependant on the dose. Carboxyl groups were not produced in helium gas. Quantitative spectral analysis indicated that the aromatic structure might be decomposed. Some comparison was made between the semicrystalline and amorphous samples. The oxygen content resulting from irradiation, of semicrystalline PEEK increased more than that of amorphous PEEK. (author)

  11. Direct Observation of Energy Detrapping in LH1-RC Complex by Two-Dimensional Electronic Spectroscopy.

    Science.gov (United States)

    Ma, Fei; Yu, Long-Jiang; Hendrikx, Ruud; Wang-Otomo, Zheng-Yu; van Grondelle, Rienk

    2017-01-18

    The purple bacterial core light harvesting antenna-reaction center (LH1-RC) complex is the simplest system able to achieve the entire primary function of photosynthesis. During the past decade, a variety of photosynthetic proteins were studied by a powerful technique, two-dimensional electronic spectroscopy (2DES). However, little attention has been paid to LH1-RC, although its reversible uphill energy transfer, trapping, and backward detrapping processes, represent a crucial step in the early photosynthetic reaction dynamics. Thus, in this work, we employed 2DES to study two LH1-RC complexes of Thermochromatium (Tch.) tepidum. By direct observation of detrapping, the complex reversible process was clearly identified and an overall scheme of the excitation evolution in LH1-RC was obtained.

  12. Oxygen adsorption on Cu-9 at. %Al(111) studied by low energy electron diffraction and Auger electron spectroscopy

    Science.gov (United States)

    Yoshitake, Michiko; Bera, Santanu; Yamauchi, Yasuhiro; Song, Weijie

    2003-07-01

    Cu-based alloys have been used for electric cables for long time. In the field of microelectronics, Al had been used for electrical wiring. However, it became clear that electromigration occurs in Al that causes breaking of wires in minute wirings. Due to this problem, Cu wiring is used in most advanced microprocessors. Cu metal is more corrosive than Al and Cu-based alloys with a small amount of Al is expected to solve problems both on electromigration and corrosion. The initial stage of corrosion is oxygen adsorption. We studied surface segregation of Al on Cu-9% Al(111) and oxygen adsorption on the surface with/without Al segregation in ultrahigh vacuum by low energy electron diffraction (LEED) and Auger electron spectroscopy. It was found that Al segregates on the surface to form (√3×√3)R30° structure and the structure vanishes above 595 K to give (1×1) structure while Al still segregates. The specimen was exposed to oxygen at different temperatures. The amount of oxygen uptake was not structure dependent but temperature dependent. Below 595 K, only a small amount of oxygen adsorbed. Between 595 and 870 K, oxygen adsorbed surface showed amorphous LEED pattern. The specimen was annealed at 1070 K after oxygen exposure. When the specimen was exposed oxygen below 870 K, the oxygen Auger intensity decreased significantly by annealing and the annealed surface showed (√3×√3)R30° structure at room temperature. When the specimen was exposed to oxygen at 870 K, diffused spots developed newly in LEED pattern but the pattern disappeared after 1070 K annealing while oxygen Auger intensity remained almost constant. Exposing the specimen to oxygen at 995 K resulted in clear spots in the LEED pattern, which were attributed to the (7/√3×7√3)R30° structure.

  13. Ultra-Broadband Two-Dimensional Electronic Spectroscopy and Pump-Probe Microscopy of Molecular Systems

    Science.gov (United States)

    Spokoyny, Boris M.

    Ultrafast spectroscopy offers an unprecedented view on the dynamic nature of chemical reactions. From charge transfer in semiconductors to folding and isomerization of proteins, these all important processes can now be monitored and in some instances even controlled on real, physical timescales. One of the biggest challenges of ultrafast science is the incredible energetic complexity of most systems. It is not uncommon to encounter macromolecules or materials with absorption spectra spanning significant portions of the visible spectrum. Monitoring a multitude of electronic and vibrational transitions, all dynamically interacting with each other on femtosecond timescales poses a truly daunting experimental task. The first part of this thesis deals with the development of a novel Two-Dimensional Electronic Spectroscopy (2DES) and its associated, advanced detection methodologies. Owing to its ultra-broadband implementation, this technique enables us to monitor femtosecond chemical dynamics that span the energetic landscape of the entire visible spectrum. In order to demonstrate the utility of our method, we apply it to two laser dye molecules, IR-144 and Cresyl Violet. Variation of photophysical properties on a microscopic scale in either man-made or naturally occurring systems can have profound implications on how we understand their macroscopic properties. Recently, inorganic hybrid perovskites have been tapped as the next generation solar energy harvesting materials. Their remarkable properties include low exciton binding energy, low exciton recombination rates and long carrier diffusion lengths. Nevertheless, considerable variability in device properties made with nearly identical preparation methods has puzzled the community. In the second part of this thesis we use non-linear pump probe microscopy to study the heterogeneous nature of femtosecond carrier dynamics in thin film perovskites. We show that the local morphology of the perovskite thin films has a

  14. 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.

  15. 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.

  16. Electronic structure investigation of atomic layer deposition ruthenium(oxide) thin films using photoemission spectroscopy

    International Nuclear Information System (INIS)

    Schaefer, Michael; Schlaf, Rudy

    2015-01-01

    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 (Ru 0 ) and its oxide (RuO 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 0 and RuO 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 2 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 RuO 2 /OH compound whose surface is saturated with hydroxyl groups

  17. Electronic properties of semiconducting naphthalene bisimide derivatives—Ultraviolet photoelectron spectroscopy versus electrochemistry

    International Nuclear Information System (INIS)

    Rybakiewicz, Renata; Gawrys, Pawel; Tsikritzis, Dimitris; Emmanouil, Konstantinos; Kennou, Stella; Zagorska, Malgorzata; Pron, Adam

    2013-01-01

    Highlights: ► Electrochemical method for the determination of the ionization potential (IP) in organic semiconductors was validated. ► Excellent correlation was found between the IP values determined electrochemically and by UPS for naphthalene bisimides. ► Excellent correlation was found between the calculated (DFT) IP values and the experimentally determined ones. -- Abstract: Key parameters for organic semiconductors used as active layers in organic electronic devices are: solution processability, charge carriers mobility as well as the electron affinity (EA) and the ionization potential (IP) which determine their redox properties and by consequence their air stability. The purpose of the present work was to investigate the influence of different substituents at imide nitrogen atom (alkylaryl, thienylene and triarylamine) and at naphthalene core (triarylamine) on the IP and EA values in recently synthesized naphthalene bisimide derivatives, tested as promising semiconductors for flexible n-channel or ambipolar organic field effect transistors (OFETs). The ionization potentials were determined by Ultra-violet Photoelectron Spectroscopy (UPS) for thin semiconductor films evaporated in ultra-high vacuum. The values obtained by photoelectron spectroscopy were compared with the ones determined from electrochemical investigations of the semiconductors dissolved in an electrolyte solution. Using cyclic voltammetry the IPs was estimated from the onset of the first oxidation peak whereas EAs from the onset of the first reduction peak. In cases where it was not possible to record the oxidation wave in the electrolyte electrochemical window, the IPs values were calculated by subtracting the energy of the spectroscopically (UV–vis–NIR) determined band gap from the EA values and changing the sign. A good correlation between the spectroscopic (UPS) and electrochemical data was found

  18. Studies of the structure of insulin fibrils by Fourier transform infrared (FTIR) spectroscopy and electron microscopy.

    Science.gov (United States)

    Nielsen, L; Frokjaer, S; Carpenter, J F; Brange, J

    2001-01-01

    Fibril formation (aggregation) of insulin was investigated in acid media by visual inspection, transmission electron microscopy (TEM), and Fourier transform infrared (FTIR) spectroscopy. Insulin fibrillated faster in hydrochloric acid than in acetic acid at elevated temperatures, whereas the fibrillation tendencies were reversed at ambient temperatures. Electron micrographs showed that bovine insulin fibrils consisted of long fibers with a diameter of 5 to 10 nm and lengths of several microns. The fibrils appeared either as helical filaments (in hydrochloric acid) or arranged laterally in bundles (in acetic acid, NaCl). Freeze-thawing cycles broke the fibrils into shorter segments. FTIR spectroscopy showed that the native secondary structure of insulin was identical in hydrochloric acid and acetic acid, whereas the secondary structure of fibrils formed in hydrochloric acid was different from that formed in acetic acid. Fibrils of bovine insulin prepared by heating or agitating an acid solution of insulin showed an increased content of beta-sheet (mostly intermolecular) and a decrease in the intensity of the alpha-helix band. In hydrochloric acid, the frequencies of the beta-sheet bands depended on whether the fibrillation was induced by heating or agitation. This difference was not seen in acetic acid. Freeze-thawing cycles of the fibrils in hydrochloric acid caused an increase in the intensity of the band at 1635 cm(-1) concomitant with reduction of the band at 1622 cm(-1). The results showed that the structure of insulin fibrils is highly dependent on the composition of the acid media and on the treatment. Copyright 2001 Wiley-Liss Inc. and the American Pharmaceutical Association J Pharm Sci 90: 29-37, 2001

  19. Limitations of superfluid helium droplets as host system revealed by electronic spectroscopy of embedded molecules

    Energy Technology Data Exchange (ETDEWEB)

    Premke, Tobias

    2016-02-19

    Superfluid helium nanodroplets serve a unique cryogenic host system ideal to prepare cold molecules and clusters. Structures as well as dynamic processes can be examined by means of high resolution spectroscopy. Dopant spectra are accompanied by helium-induced spectroscopic features which reveal information on the dopant to helium interaction. For this reason the experimental research focuses on the investigation of such helium-induced effects in order to provide new information on the microsolvation inside the droplets. Since the quantitative understanding of helium-induced spectral features is essential to interpret molecular spectra recorded in helium droplets, this study contributes further experimental details on microsolvation in superfluid helium droplets. For this purpose two contrary systems were examined by means of high resolution electronic spectroscopy. The first one, phthalocyanine (Pc), is a planar organic molecule offering a huge and planar surface to the helium atoms and thus, the non-superfluid helium solvation layer can form different structures. The second system is iodine and in contrast to Pc it is of simple molecular shape. That means that in this case different complex structures of the non-superfluid helium solvation layer and the dopant can be expected to be avoided. Thus, both molecules should show clear differences in their microsolvation behavior. In this work a detailed examination of different spectroscopic properties of phthalocyanine is given by means of fluorescence excitation and dispersed emission spectroscopy. It raises legitimate doubts about the assignment of experimentally observed signals to features predicted by the model of the microsolvation. Even though there are no experimental observations which disprove the empirical model for the solvation in helium droplets, an unambiguous assignment of the helium-induced spectroscopic structures is often not possible. In the second part of this work, the investigation of the

  20. Spectroscopy of electronic transitions in Polycyclic Aromatic Hydrocarbon cations and their clusters

    International Nuclear Information System (INIS)

    Friha, Hela

    2012-01-01

    This thesis is an experimental study of the electronic spectroscopy of cations of Polycyclic Aromatic Hydrocarbons (PAHs) and their aggregates in conditions close to those of the interstellar medium (ISM), i.e. cold and totally isolated in the gas phase. It is related to the astrophysical context of the interstellar medium (ISM), in particular on the question of the possible link between interstellar PAHs and Diffuse Interstellar Bands (DIBs). The purpose of this thesis is to provide laboratory spectra which can be directly compared to the spectra of DIBs. Indeed these bands are the oldest spectroscopy riddle in astrophysics which remained unanswered for nearly 100 years and whose key is still looked for. A special attention is given to the methylated derivatives of PAHs species detected in many interstellar environments, cationic PAH dimers (the simplest PAH clusters). These clusters have been proposed as a model of the very small grains, which contribute to the formation of interstellar PAHs and whose chemical composition remains uncertain. This thesis has been mainly devoted to the determination of the electronic spectra of naphthalene cation monomer (Np + ) and its methylated derivative (2-MeN p + ), as well as the associated homogeneous dimers. The experimental method used is based on the photodissociation of van der Waals complexes PAH + m -Ar n (argon atoms spectators), prepared by UV laser photoionization in a supersonic jet. This technique combines different experimental tools, namely: molecular beam mass spectrometry and laser spectroscopy as well as physical tools such as the handling of clusters VdW PAH + m -Ar n , the detection of photo-fragments, the measurement of photodissociation efficiency. The identification of the fragments by the photodissociation of VdW clusters allowed us to determine the different possible fragmentation channels and especially to obtain the spectra the charge resonance transition and the first allowed transition to locally

  1. Quantitative electron microscopy and spectroscopy of MgB2 wires and tapes

    International Nuclear Information System (INIS)

    Birajdar, B; Peranio, N; Eibl, O

    2008-01-01

    In MgB 2 the correlation of microstructure with superconducting properties, in particular the critical current density, requires powerful analytical tools. Critical current densities and electrical resistivities of different MgB 2 superconductors differ by orders of magnitudes and the current limiting mechanisms have not been fully understood. Granularity of MgB 2 is one significant reason for reduced critical current densities and is introduced intrinsically by the anisotropy of B c2 but also extrinsically by the microstructure of the material. B c2 enhancement by doping is another important challenge for chemical analysis and, at present, doping levels are not well controlled on the sub-μm scale. In this paper the quantitative electron microscopy and spectroscopy methods essential for the microstructural analysis of MgB 2 are described. By quantitative electron microscopy and spectroscopy we mean a combined SEM and TEM analysis that covers various length scales from μm to nm. Contamination-free sample preparation, chemical mapping including B, and advanced chemical quantification using x-ray microanalysis were essential elements of the applied methodology. The methodology was applied to in situ and ex situ MgB 2 wires and tapes with and without SiC additives. Quantitative B analysis by EDX spectroscopy was applied quantitatively in the SEM and TEM, which is a major achievement. Although MgB 2 is a binary system, the thermodynamics of phase formation is complex, and the complexity is dramatically increased if additives like SiC are used. The small, sub-μm grain sizes of the matrix and secondary phases require TEM methods. However, granularity on the μm scale was also identified and underlines the importance of the combined SEM and TEM studies. Significant differences in the microstructure were observed for in situ and ex situ samples. This holds particularly if SiC was added and yielded Mg 2 Si for in situ samples annealed at 600-650 deg. C and Mg-Si-O phases

  2. Overview of the current spectroscopy effort on the Livermore electron beam ion traps

    International Nuclear Information System (INIS)

    Beiersdorfer, P.; Lopez-Urrutia, J.C.; Brown, G.

    1995-01-01

    An overview is given of the current spectroscopic effort on the Livermore electron beam ion trap facilities. The effort focuses on four aspects: spectral line position, line intensity, temporal evolution, and line shape. Examples of line position measurements include studies of the K-shell transitions in heliumlike Kr 34+ and the 2s-2p intrashell transitions in lithiumlike Th 87+ and U 89+ , which provide benchmark values for testing the theory of relativistic and quantum electrodynamical contributions in high-Z ions. Examples of line intensity measurements are provided by measurements of the electron-impact excitation and dielectronic recombination cross sections of heliumlike transition-metal ions Ti 20+ through CO 25+ . A discussion of radiative lifetime measurements of metastable levels in heliumlike ions is given to illustrate the time-resolved spectroscopy techniques in the microsecond range. The authors also present a measurement of the spectral lineshape that illustrates the very low ion temperatures that can be achieved in an EBIT

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

    DEFF Research Database (Denmark)

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

    2017-01-01

    Laccases (EC 1.10.3.2) catalyse removal of an electron and a proton from phenolic hydroxyl groups, including phenolic hydroxyls in lignins, to form phenoxy radicals during reduction of O2. We employed electron paramagnetic resonance spectroscopy (EPR) for real time measurement of such catalytic...... to suspensions of the individual lignin samples produced immediate time and enzyme dose dependent increases in intensity in the EPR signal with g-values in the range 2.0047–2.0050 allowing a direct quantitative monitoring of the radical formation and thus allowed laccase enzyme kinetics assessment on lignin...... for the radical formation rate in organosolv lignin was determined by response surface methodology to pH 4.8, 33 °C and pH 5.8, 33 °C for the Tv laccase and the Mt laccase, respectively. The results verify direct radical formation action of fungal laccases on lignin without addition of mediators and the EPR...

  4. Probing hot-electron effects in wide area plasmonic surfaces using X-ray photoelectron spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Ayas, Sencer; Cupallari, Andi; Dana, Aykutlu, E-mail: aykutlu@unam.bilkent.edu.tr [UNAM Institute of Materials Science and Nanotechnology, Bilkent University, 06800 Ankara (Turkey)

    2014-12-01

    Plasmon enhanced hot carrier formation in metallic nanostructures increasingly attracts attention due to potential applications in photodetection, photocatalysis, and solar energy conversion. Here, hot-electron effects in nanoscale metal-insulator-metal (MIM) structures are investigated using a non-contact X-ray photoelectron spectroscopy based technique using continuous wave X-ray and laser excitations. The effects are observed through shifts of the binding energy of the top metal layer upon excitation with lasers of 445, 532, and 650 nm wavelength. The shifts are polarization dependent for plasmonic MIM grating structures fabricated by electron beam lithography. Wide area plasmonic MIM surfaces fabricated using a lithography free route by the dewetting of evaporated Ag on HfO{sub 2} exhibit polarization independent optical absorption and surface photovoltage. Using a simple model and making several assumptions about the magnitude of the photoemission current, the responsivity and external quantum efficiency of wide area plasmonic MIM surfaces are estimated as 500 nA/W and 11 × 10{sup −6} for 445 nm illumination.

  5. Using elastic peak electron spectroscopy for enhanced depth resolution in sputter profiling

    International Nuclear Information System (INIS)

    Hofmann, S.; Kesler, V.

    2002-01-01

    Elastic peak electron spectroscopy (EPES) is an alternative to AES in sputter depth profiling of thin film structures. In contrast to AES, EPES depth profiling is not influenced by chemical effects. The high count rate ensures a good signal to noise ratio, that is lower measurement times and/or higher precision. In addition, because of the elastically scattered electrons travel twice through the sample, the effective escape depth is reduced, an important factor for the depth resolution function. Thus, the depth resolution is increased. EPES depth profiling was successfully applied to a Ge/Si multilayer structure. For an elastic peak energy of 1.0 keV the information depth is considerably lower (0.8 nm) as compared to the Ge (LMM, 1147 eV) peak (1.6 nm) used in AES depth profiling, resulting in a respectively improved depth resolution for EPES profiling under otherwise similar profiling conditions. EPES depth profiling is successfully applied to measure small diffusion lengths at Ge/Si interfaces of the order of 1 nm. (Authors)

  6. Electronic properties of novel topological quantum materials studied by angle-resolved photoemission spectroscopy (ARPES)

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Yun [Iowa State Univ., Ames, IA (United States)

    2016-12-17

    The discovery of quantum Hall e ect has motivated the use of topology instead of broken symmetry to classify the states of matter. Quantum spin Hall e ect has been proposed to have a separation of spin currents as an analogue of the charge currents separation in quantum Hall e ect, leading us to the era of topological insulators. Three-dimensional analogue of the Dirac state in graphene has brought us the three-dimensional Dirac states. Materials with three-dimensional Dirac states could potentially be the parent compounds for Weyl semimetals and topological insulators when time-reversal or space inversion symmetry is broken. In addition to the single Dirac point linking the two dispersion cones in the Dirac/Weyl semimetals, Dirac points can form a line in the momentum space, resulting in a topological node line semimetal. These fascinating novel topological quantum materials could provide us platforms for studying the relativistic physics in condensed matter systems and potentially lead to design of new electronic devices that run faster and consume less power than traditional, silicon based transistors. In this thesis, we present the electronic properties of novel topological quantum materials studied by angle-resolved photoemission spectroscopy (ARPES).

  7. Status of electron temperature and density measurement with beam emission spectroscopy on thermal helium at TEXTOR

    International Nuclear Information System (INIS)

    Schmitz, O; Schweer, B; Pospieszczyk, A; Lehnen, M; Samm, U; Unterberg, B; Beigman, I L; Vainshtein, L A; Kantor, M; Xu, Y; Krychowiak, M

    2008-01-01

    Beam emission spectroscopy on thermal helium is used at the TEXTOR tokamak as a reliable method to obtain radial profiles of electron temperature T e (r, t) and electron density n e (r, t). In this paper the experimental realization of this method at TEXTOR and the status of the atomic physics employed as well as the major factors for the measurement's accuracy are evaluated. On the experimental side, the hardware specifications are described and the impact of the beam atoms on the local plasma parameters is shown to be negligible. On the modeling side the collisional-radiative model (CRM) applied to infer n e and T e from the measured He line intensities is evaluated. The role of proton and deuteron collisions and of charge exchange processes is studied with a new CRM and the impact of these so far neglected processes appears to be of minor importance. Direct comparison to Thomson scattering and fast triple probe data showed that for high densities n e > 3.5 x 10 19 m -3 the T e values deduced with the established CRM are too low. However, the new atomic data set implemented in the new CRM leads in general to higher T e values. This allows us to specify the range of reliable application of BES on thermal helium to a range of 2.0 x 10 18 e 19 m -3 and 10 eV e < 250 eV which can be extended by routine application of the new CRM.

  8. Detection of oxygen-related defects in GaAs by exo-electron emission spectroscopy

    Science.gov (United States)

    Hulluvarad, Shiva S.; Naddaf, M.; Bhoraskar, S. V.

    2001-10-01

    The influence of intentional introduction of oxygen, at the surface of GaAs, on its native surface states was studied. Oxygen was made to interact with the surface of GaAs by three different means: (1) by growing native oxides, (2) exposing to oxygen plasma in an electron cyclotron resonance (ECR) plasma reactor and by (3) high energy oxygen ion irradiation. Thermally stimulated exo-electron emission (TSEE) spectroscopy was used to estimate the relative densities and energies of the surface states induced by the three different modes of introducing oxygen. Out of the two native defect levels found in GaAs by TSEE; at 325 K (0.7 eV below Ec) and at 415 K (0.9 below Ec); the former is seen to get broadened or split into multiple peaks in each of the methods. Multiple peaks in TSEE signify the presence of a closely spaced band of defect levels. Therefore the results exclusively point out that oxygen-related complexes contribute to the formation of a band of defects centered at 325 K in TSEE which is correlated to an energy level 0.7 eV below Ec known as the EL2 defect level. The results reported in this paper thus confirm that the TSEE peak at 0.7 eV below Ec is related to oxygen induced defects whereas the peak at 0.9 eV is not affected by the presence of oxygen-related species.

  9. Joint density of states of wide-band-gap materials by electron energy loss spectroscopy

    International Nuclear Information System (INIS)

    Fan, X.D.; Peng, J.L.; Bursill, L.A.

    1998-01-01

    Kramers-Kronig analysis for parallel electron energy loss spectroscopy (PEELS) data is developed as a software package. When used with a JEOL 4000EX high-resolution transmission electron microscope (HRTEM) operating at 100 keV this allows us to obtain the dielectric function of relatively wide band gap materials with an energy resolution of approx 1.4 eV. The imaginary part of the dielectric function allows the magnitude of the band gap to be determined as well as the joint-density-of-states function. Routines for obtaining three variations of the joint-density of states function, which may be used to predict the optical and dielectric response for angle-resolved or angle-integration scattering geometries are also described. Applications are presented for diamond, aluminum nitride (AlN), quartz (SiO 2 ) and sapphire (Al 2 O 3 ). The results are compared with values of the band gap and density of states results for these materials obtained with other techniques. (authors)

  10. Electron phonon couplings in 2D perovskite probed by ultrafast photoinduced absorption spectroscopy

    Science.gov (United States)

    Huynh, Uyen; Ni, Limeng; Rao, Akshay

    We use the time-resolved photoinduced absorption (PIA) spectroscopy with 20fs time resolution to investigate the electron phonon coupling in the self-assembled hybrid organic layered perovskite, the hexyl ammonium lead iodide compound (C6H13NH3)2 (PbI4) . The coupling results in the broadening and asymmetry of its temperature-dependence photoluminescence spectra. The exact time scale of this coupling, however, wasn't reported experimentally. Here we show that using an ultrashort excitation pulse allows us to resolve from PIA kinetics the oscillation of coherent longitudinal optical phonons that relaxes and self-traps electrons to lower energy states within 200 fs. The 200fs relaxation time is equivalent to a coupling strength of 40meV. Two coupled phonon modes are also identified as about 100 cm-1 and 300 cm-1 from the FFT spectrum of the PIA kinetics. The lower energy mode is consistent with previous reports and Raman spectrum but the higher energy one hasn't been observed before.

  11. Revisiting the inelastic electron tunneling spectroscopy of single hydrogen atom adsorbed on the Cu(100) surface

    International Nuclear Information System (INIS)

    Jiang, Zhuoling; Wang, Hao; Sanvito, Stefano; Hou, Shimin

    2015-01-01

    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 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

  12. 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...

  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. Mapping bright and dark modes in gold nanoparticle chains using electron energy loss spectroscopy.

    Science.gov (United States)

    Barrow, Steven J; Rossouw, David; Funston, Alison M; Botton, Gianluigi A; Mulvaney, Paul

    2014-07-09

    We present a scanning transmission electron microscopy-electron energy loss spectroscopy (STEM-EELS) investigation of gold nanosphere chains with lengths varying from 1 to 5 particles. We show localized EELS signals from the chains and identify energy-loss peaks arising due to l = 1, 2, 3, 4, and 5 plasmon modes through the use of EELS mapping. We also show the evolution of the energy of these modes as the length of a given chain increases, and we find that a chain containing N particles can accommodate at least N experimentally observable modes, in addition to the transverse mode. As the chain length is increased by the addition of one more gold particle to the chain, the new N + 1 mode becomes the highest energy mode, while the existing modes lower their energy and eventually asymptote as they delocalize along the chain. We also show that modes become increasingly difficult to detect with the EELS technique as l approaches N. The data are compared to numerical simulations.

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

    DEFF Research Database (Denmark)

    in the energies of plasmon peaks in the low loss region [5]. We use these approaches to characterize both a thick n-p junction and the 10-nm-thick p-doped layer of a working solar cell. [1] U. Kroll, C. Bucher, S. Benagli, I. Schönbächler, J. Meier, A. Shah, J. Ballutaud, A. Howling, Ch. Hollenstein, A. Büchel, M......Amorphous silicon solar cells typically consist of stacked layers deposited on plastic or metallic substrates making sample preparation for transmission electron microscopy (TEM) difficult. The amorphous silicon layer - the active part of the solar cell - is sandwiched between 10-nm-thick n- and p...... resolution using TEM is highly challenging [3]. Recently, scanning TEM (STEM) combined with electron energy-loss spectroscopy (EELS) and spherical aberration-correction has allowed the direct detection of dopant concentration of 10^20cm-3 in 65-nm-wide silicon devices [4]. Here, we prepare TEM samples...

  16. Adsorption on metal oxides: Studies with the metastable impact electron spectroscopy

    International Nuclear Information System (INIS)

    Krischok, S.; Hoefft, O.; 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 2 O, molecular adsorption takes place both on MgO and TiO 2 ; on the other hand, water-alkali coadsorption leads to hydroxide formation. In the case of CO 2 , chemisorption takes place in form of carbonate (CO 3 ) species. These originate from the CO 2 interaction with O 2- surface anions. While for CaO chemisorption takes place at regular oxygen sites, for MgO this occurs at low-coordinated oxygen ions only; for TiO 2 chemisorption requires alkali coadsorption

  17. Characterization of lipid oxidation process of beef during repeated freeze-thaw by electron spin resonance technology and Raman spectroscopy.

    Science.gov (United States)

    Chen, Qingmin; Xie, Yunfei; Xi, Jinzhong; Guo, Yahui; Qian, He; Cheng, Yuliang; Chen, Yi; Yao, Weirong

    2018-03-15

    In this study, electron spin resonance (ESR) and Raman spectroscopy were applied to characterize lipid oxidation of beef during repeated freeze-thaw (RFT). Besides the conventional indexes including peroxide values (PV), thiobarbituric acid-reactive substances (TBARS) and acid values (AV) were evaluated, the radical and molecular structure changes were also measured by ESR and Raman spectroscopy. The results showed that PV, TBARS and AV were increased (PRaman intensity of ν(CC) stretching region (1655cm -1 ) was decreased during RFT. Furthermore, lower Raman intensity ratio of I 1655 /I 1442 , I 1655 /I 1745 that determine total unsaturation was also observed. Significant correlations (pRaman spectroscopy. Our result has proved that ESR and Raman spectroscopy showed great potential in characterizing lipid oxidation process of beef during RFT. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. 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.

  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. 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

  1. Infrared photoexcitation spectroscopy of conducting polymer and C60 composites: direct evidence of photo-induced electron transfer

    NARCIS (Netherlands)

    Lee, Kwanghee; Janssen, R.A.J.; Sariciftci, N.S.; Heeger, A.J.

    1994-01-01

    We report direct spectral evidence of photoinduced electron transfer from the excited state of conducting polymer onto C60 by infrared photoexcitation spectroscopy, from 0.01 eV (100 cm-1) to 1.3 eV (11,000 cm-1). The photoinduced absorption spectra of poly(3-octylthiophene) (P30T) and

  2. Comparing the photophysics of the two forms of the Orange Carotenoid Protein using 2D electronic spectroscopy

    Directory of Open Access Journals (Sweden)

    Mathies R.A.

    2013-03-01

    Full Text Available Broadband two-dimensional electronic spectroscopy is applied to investigate the photophysics of the photoactive orange carotenoid protein, which is involved in nonphotochemical quenching in cyanobacteria. Differences in dynamics between the light and dark forms arise from the different structure of the carotenoid in the protein pocket, with consequences for the biological role of the two forms.

  3. On the Electronic Structure of Mesitylnickel Complexes of .alpha.-Diimines-Combining Structural Data, Spectroscopy and Calculations

    Czech Academy of Sciences Publication Activity Database

    Klein, A.; Bertagnolli, H.; Feth, M. P.; Záliš, Stanislav

    -, č. 13 (2004), s. 2784-2796 ISSN 1434-1948 R&D Projects: GA MŠk OC D14.20 Institutional research plan: CEZ:AV0Z4040901 Keywords : density functional calculations * electronic structure * Raman spectroscopy Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.336, year: 2004

  4. Photoleucine Survives Backbone Cleavage by Electron Transfer Dissociation. A Near-UV Photodissociation and Infrared Multiphoton Dissociation Action Spectroscopy Study

    Czech Academy of Sciences Publication Activity Database

    Shaffer, C. J.; Martens, J.; Marek, Aleš; Oomens, J.; Tureček, F.

    2016-01-01

    Roč. 27, č. 7 (2016), s. 1176-1185 ISSN 1044-0305 Institutional support: RVO:61388963 Keywords : peptide ions * electron transfer dissociation * photoleucine label * near-UV photodissociation * infrared multiphoton dissociation action spectroscopy Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.786, year: 2016

  5. PHOTOELECTRON-SPECTROSCOPY STUDY OF THE ELECTRONIC-STRUCTURE OF THE INCOMMENSURATE INTERGROWTH COMPOUNDS (SBS)(1.15)(TIS2)(N) WITH N=1, 2

    NARCIS (Netherlands)

    REN, Y; HAAS, C; WIEGERS, GA

    1995-01-01

    The electronic structure of the inorganic misfit-layer compounds (SbS)(1.15)(TiS2)(n) (n = 1,2) has been investigated using x-ray photoemission spectroscopy (XPS), ultraviolet photoemission spectroscopy (UPS) and x-ray absorption spectroscopy (XAS). These compounds are built of alternating modulated

  6. Elucidating the design principles of photosynthetic electron-transfer proteins by site-directed spin labeling EPR spectroscopy.

    Science.gov (United States)

    Ishara Silva, K; Jagannathan, Bharat; Golbeck, John H; Lakshmi, K V

    2016-05-01

    Site-directed spin labeling electron paramagnetic resonance (SDSL EPR) spectroscopy is a powerful tool to determine solvent accessibility, side-chain dynamics, and inter-spin distances at specific sites in biological macromolecules. This information provides important insights into the structure and dynamics of both natural and designed proteins and protein complexes. Here, we discuss the application of SDSL EPR spectroscopy in probing the charge-transfer cofactors in photosynthetic reaction centers (RC) such as photosystem I (PSI) and the bacterial reaction center (bRC). Photosynthetic RCs are large multi-subunit proteins (molecular weight≥300 kDa) that perform light-driven charge transfer reactions in photosynthesis. These reactions are carried out by cofactors that are paramagnetic in one of their oxidation states. This renders the RCs unsuitable for conventional nuclear magnetic resonance spectroscopy investigations. However, the presence of native paramagnetic centers and the ability to covalently attach site-directed spin labels in RCs makes them ideally suited for the application of SDSL EPR spectroscopy. The paramagnetic centers serve as probes of conformational changes, dynamics of subunit assembly, and the relative motion of cofactors and peptide subunits. In this review, we describe novel applications of SDSL EPR spectroscopy for elucidating the effects of local structure and dynamics on the electron-transfer cofactors of photosynthetic RCs. Because SDSL EPR Spectroscopy is uniquely suited to provide dynamic information on protein motion, it is a particularly useful method in the engineering and analysis of designed electron transfer proteins and protein networks. This article is part of a Special Issue entitled Biodesign for Bioenergetics--the design and engineering of electronic transfer cofactors, proteins and protein networks, edited by Ronald L. Koder and J.L. Ross Anderson. Copyright © 2016. Published by Elsevier B.V.

  7. Spectroscopie du Furanne et du Thiophene Par Diffusion Inelastique D'electrons

    Science.gov (United States)

    Lotfi, Said

    Nous avons etudie les molecules de furanne ( rm C_4H_4O) et de thiophene (rm C_4H_4O) au moyen de la spectroscopie de diffusion inelastique d'electrons. Pour (rm C_4H_4O), les spectres realises dans differentes conditions d'energie d'impact et d'angle de diffusion contiennent des singularites ou des families de pics correspondant a: (1) des vibrations de l'etat fondamental dans le domaine 0-0.5 eV, (2) des etats triplets ^3 B_1 et ^3 A_1 qui dominent la region 3-5.5 eV, (3) des etats de valences, entre 5 et 10 eV, dont certains son accompagnes de progressions vibrationnelles, soit ~ A _1B_2, ~ B ^1A_1 et ~ C ^1A_1, (4) toujours entre 5 et 10 eV, deux series de Ryhdberg (rm 1a_2to nda_2 et rm 1a_2to npb_2) qui convergent vers la premiere limite d'ionisation de la molecule, avec une progression vibrationnelle associee au mdoe nu_4 pour la seconde, et une troisieme serie (rm 2b_1to nsa_1 ) convergent vers la seconde limite d'ionisation accompagnee de la progression de mode nu _1. Pour rm C_4H_4S, nos spectres presentent les memes etats de vibration et les memes etats triplets que pour rm C_4H _4O. Nous avons releve egalement, dans la region de 5 a 10 eV, des etats de valence ~ A ^1A_1 (ou ~ A ^1B_2), ~ B ^1A_1 (ou ~ B ^1B _2) et ~ C ^1A_1 (ou ~ C ^1B_2). Pour la premiere fois, par la spectroscopie de diffusion inelastique d'electrons, de nombreux pics ont ete identifies et attribues, dans le cadre de ce travail. Il s'agit, notamment, des etats de vibration de l'etat electronique fondamental de ces molecules et egalement de certains etats de Rydberg dans le cas du furanne.

  8. Investigation of the chemistry of the dielectric/FeCoTb interface by x-ray photoelectron spectroscopy and Auger electron spectroscopy

    International Nuclear Information System (INIS)

    Stickle, W.F.; Coulman, D.

    1987-01-01

    The interfacial chemistry of magneto-optic structures of sputter deposited SiO, SiO 2 , Si 3 N 4 /FeCoTb/SiO, SiO 2 , and Si 3 N 4 was studied in detail by x-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES). XPS and AES depth profiles have revealed a substantial amount of redox chemistry at the dielectric/rare-earth transition metal interfaces. The chemical reactions occur preferentially with the terbium as revealed in the XPS portion of the study by the formation of terbium oxide and terbium silicide. In the case of Si 3 N 4 evidence of TbN/sub x/ has also been observed. ''As deposited'' and annealed samples of the magneto-optic structures are compared and contrasted. It is concluded that Si 3 N 4 is a superior dielectric for magneto-optic media

  9. Femtosecond stimulated Raman spectroscopy as a tool to detect molecular vibrations in ground and excited electronic states

    Energy Technology Data Exchange (ETDEWEB)

    Gelin, Maxim F.; Domcke, Wolfgang [Department of Chemistry, Technische Universität München, D-85747 Garching (Germany); Rao, B. Jayachander [Departamento de Química and Centro de Química, Universidade de Coimbra, 3004-535 Coimbra (Portugal)

    2016-05-14

    We give a detailed theoretical analysis of the simplest variant of femtosecond stimulated Raman spectroscopy, where a picosecond Raman pump pulse and a femtosecond Raman probe pulse are applied resonantly to a chromophore in thermal equilibrium in the ground electronic state. We demonstrate that this technique is capable of the detection of dephasing-free Raman-like lines revealing vibrational modes not only in the electronic ground state but also in the excited electronic state of the chromophore. The analytical results obtained with simplifying assumptions for the shape of the laser pulses are substantiated by numerical simulations with realistic laser pulses, employing the equation-of-motion phase-matching approach.

  10. Electron capture study of Ar[sup 7+] + He(H[sub 2]) by U. V. spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Bouchama, T. (Inst. de Physique, Univ. des Sciences et de la Technologie, Alger (Algeria)); El Motassadeq, A. (Lab. Traitement du Signal et Instrumentation, Univ. Jean Monnet, 42 Saint-Etienne (France)); Salmoun, A. (Univ. Cady Ayad, Marrakech (Morocco)); Druetta, M. (Lab. Traitement du Signal et Instrumentation, Univ. Jean Monnet, 42 Saint-Etienne (France)); Church, D.A. (Dept. of Physics, Texas AM Univ., College Station, TX (United States))

    1993-11-01

    Partial nl and total cross-sections for the low energy collisions Ar[sup 7+] + He(H[sub 2]) at 35-70 keV have been measured by photon spectroscopy. In addition to single electron capture, one electron capture with excitation of a core electron has been observed and measured. Comparisons with calculations based on the Extended Classical Over-Barrier (ECB) model and the assumption of conservation of angular momentum show good agreement between the experimental and predicted l-distributions. (orig.).

  11. Electronic structure of C r2AlC as observed by angle-resolved photoemission spectroscopy

    Science.gov (United States)

    Ito, Takahiro; Pinek, Damir; Fujita, Taishi; Nakatake, Masashi; Ideta, Shin-ichiro; Tanaka, Kiyohisa; Ouisse, Thierry

    2017-11-01

    We investigate the electronic band structure and Fermi surfaces (FSs) of C r2AlC single crystals with angle-resolved photoemission spectroscopy. We evidence hole bands centered around the M points and electron bands centered around the Γ point in reciprocal space. Electron and hole bands exhibit an open, tubular structure along the c axis, confirming the quasi-two-dimensional character of this highly anisotropic, nanolamellar compound. Dependence of the photoionization cross sections on beam light polarization and orientation allows us to assess the orbital character of each observed band locally. Despite some differences, density functional theory calculations show a good agreement with experiment.

  12. Correlation effects in magnetic materials: An ab initio investigation on electronic structure and spectroscopy

    International Nuclear Information System (INIS)

    Minár, J.; Braun, J.; Ebert, H.

    2013-01-01

    Highlights: ► We compare spin-resolved ARPES data of ferromagnetic 3d transition metals to many-body LSDA + DMFT based spectroscopic calculations. ► We document LSDA + DMFT provides a detailed and reliable interpretation of the data. ► We demonstrate that local correlations are dominant in Ni, whereas non-local correlations are important in Fe and Co. ► We reproduce the 6 eV satellite structure in ferromagnetic Ni LDSDA + DMFT in combination with the one-step model of photoemission provides a more or less complete description of the electronic structure of Fe, Co and Ni. -- Abstract: Various technical developments enlarged the potential of angle-resolved photoemission spectroscopy (ARPES) tremendously during the last two decades. In particular improved momentum and energy resolution in combination with spin-resolution as well as the use of photon energies from few eV up to several keV makes ARPES a rather unique tool to investigate the electronic properties of solids and surfaces. Obviously, this rises the need for a corresponding theoretical formalism that allows to accompany experimental ARPES studies in an adequate way. As will be demonstrated by several examples this goal could be achieved by various recent developments on the basis of density functional theory (DFT) in combination with dynamical mean field theory (DMFT) and with the one-step model of photoemission (1SM). A concrete realization of electronic structure calculations in the framework of multiple scattering theory further more provides direct access to the spectral function of the initial states via the one-electron Green function. Based on this bare spectral function matrix-element and final-state effects as well as surface related features may be calculated in addition using the one-step formalism that offers the possibility to analyse corresponding angle-resolved photoemission experiments in a quantitative sense. The impact of chemical disorder can be handled by means of the coherent

  13. Two dimensional CCD [charged coupled device] arrays as parallel detectors in electron energy loss and x-ray wavelength dispersive spectroscopy

    International Nuclear Information System (INIS)

    Zaluzec, N.J.

    1988-08-01

    Parallel detection systems for spectroscopy have generally been based upon linear detector arrays. Replacing the linear arrays with two dimensional systems yields more complicated devices; however, there are corresponding benefits which can be realized for both x-ray and electron energy loss spectroscopy. The operational design of these systems, as well as preliminary results from the construction of such a device used for electron spectroscopy, are presented. 10 refs., 8 figs

  14. Discrimination of Apple Liqueurs (Nalewka) Using a Voltammetric Electronic Tongue, UV-Vis and Raman Spectroscopy.

    Science.gov (United States)

    Śliwińska, Magdalena; Garcia-Hernandez, Celia; Kościński, Mikołaj; Dymerski, Tomasz; Wardencki, Waldemar; Namieśnik, Jacek; Śliwińska-Bartkowiak, Małgorzata; Jurga, Stefan; Garcia-Cabezon, Cristina; Rodriguez-Mendez, Maria Luz

    2016-10-09

    The capability of a phthalocyanine-based voltammetric electronic tongue to analyze strong alcoholic beverages has been evaluated and compared with the performance of spectroscopic techniques coupled to chemometrics. Nalewka Polish liqueurs prepared from five apple varieties have been used as a model of strong liqueurs. Principal Component Analysis has demonstrated that the best discrimination between liqueurs prepared from different apple varieties is achieved using the e-tongue and UV-Vis spectroscopy. Raman spectra coupled to chemometrics have not been efficient in discriminating liqueurs. The calculated Euclidean distances and the k-Nearest Neighbors algorithm (kNN) confirmed these results. The main advantage of the e-tongue is that, using PLS-1, good correlations have been found simultaneously with the phenolic content measured by the Folin-Ciocalteu method (R² of 0.97 in calibration and R² of 0.93 in validation) and also with the density, a marker of the alcoholic content method (R² of 0.93 in calibration and R² of 0.88 in validation). UV-Vis coupled with chemometrics has shown good correlations only with the phenolic content (R² of 0.99 in calibration and R² of 0.99 in validation) but correlations with the alcoholic content were low. Raman coupled with chemometrics has shown good correlations only with density (R² of 0.96 in calibration and R² of 0.85 in validation). In summary, from the three holistic methods evaluated to analyze strong alcoholic liqueurs, the voltammetric electronic tongue using phthalocyanines as sensing elements is superior to Raman or UV-Vis techniques because it shows an excellent discrimination capability and remarkable correlations with both antioxidant capacity and alcoholic content-the most important parameters to be measured in this type of liqueurs.

  15. Detection of oxygen-related defects in GaAs by exo-electron emission spectroscopy

    International Nuclear Information System (INIS)

    Hulluvarad, Shiva S.; Naddaf, M.; Bhoraskar, S.V.

    2001-01-01

    The influence of intentional introduction of oxygen, at the surface of GaAs, on its native surface states was studied. Oxygen was made to interact with the surface of GaAs by three different means: (1) by growing native oxides, (2) exposing to oxygen plasma in an electron cyclotron resonance (ECR) plasma reactor and by (3) high energy oxygen ion irradiation. Thermally stimulated exo-electron emission (TSEE) spectroscopy was used to estimate the relative densities and energies of the surface states induced by the three different modes of introducing oxygen. Out of the two native defect levels found in GaAs by TSEE; at 325 K (0.7 eV below E c ) and at 415 K (0.9 below E c ); the former is seen to get broadened or split into multiple peaks in each of the methods. Multiple peaks in TSEE signify the presence of a closely spaced band of defect levels. Therefore the results exclusively point out that oxygen-related complexes contribute to the formation of a band of defects centered at 325 K in TSEE which is correlated to an energy level 0.7 eV below E c known as the EL2 defect level. The results reported in this paper thus confirm that the TSEE peak at 0.7 eV below E c is related to oxygen induced defects whereas the peak at 0.9 eV is not affected by the presence of oxygen-related species

  16. Detection of oxygen-related defects in GaAs by exo-electron emission spectroscopy

    International Nuclear Information System (INIS)

    Hulluvarad, Shiva S.; Naddaf, M.; Bhoraskar, S.V.

    2004-01-01

    The influence of intentional introduction of oxygen, at the surface of GaAs, on its native surface states was studied. Oxygen was made to interact with the surface of GaAs by three different means: (1) by growing native oxides, (2) exposing to oxygen plasma in an electron cyclotron resonance (ECR) plasma reactor and by (3) high energy oxygen ion irradiation. Thermally stimulated exo-electron emission (TSEE) spectroscopy was used to estimate the relative densities and energies of the surface states induced by the three different modes of introducing oxygen. Out of the two native defect levels found in GaAs by TSEE; at 325 K (0.7 eV below E c ) and at 415 K (0.9 below E c ); the former is seen to get broadened or split into multiple peaks in each of the methods. Multiple peaks in TSEE signify the presence of a closely spaced band of defect levels. Therefore the results exclusively point out that oxygen-related complexes contribute to the formation of a band of defects centered at 325 K in TSEE which is correlated to an energy level 0.7 eV below E c known as the EL2 defect level. The results reported in this paper thus confirm that the TSEE peak at 0.7 eV below E c is related to oxygen induced defects whereas the peak at 0.9 eV is not affected by the presence of oxygen-related species. (author)

  17. Detection of oxygen-related defects in GaAs by exo-electron emission spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Hulluvarad, Shiva S.; Naddaf, M.; Bhoraskar, S.V. E-mail: svb@physics.unipune.ernet.in

    2001-10-01

    The influence of intentional introduction of oxygen, at the surface of GaAs, on its native surface states was studied. Oxygen was made to interact with the surface of GaAs by three different means: (1) by growing native oxides, (2) exposing to oxygen plasma in an electron cyclotron resonance (ECR) plasma reactor and by (3) high energy oxygen ion irradiation. Thermally stimulated exo-electron emission (TSEE) spectroscopy was used to estimate the relative densities and energies of the surface states induced by the three different modes of introducing oxygen. Out of the two native defect levels found in GaAs by TSEE; at 325 K (0.7 eV below E{sub c}) and at 415 K (0.9 below E{sub c}); the former is seen to get broadened or split into multiple peaks in each of the methods. Multiple peaks in TSEE signify the presence of a closely spaced band of defect levels. Therefore the results exclusively point out that oxygen-related complexes contribute to the formation of a band of defects centered at 325 K in TSEE which is correlated to an energy level 0.7 eV below E{sub c} known as the EL2 defect level. The results reported in this paper thus confirm that the TSEE peak at 0.7 eV below E{sub c} is related to oxygen induced defects whereas the peak at 0.9 eV is not affected by the presence of oxygen-related species.

  18. A combined photoelectron spectroscopy and relativistic ab initio studies of the electronic structures of UFO and UFO-

    Science.gov (United States)

    Roy, Soumendra K.; Jian, Tian; Lopez, Gary V.; Li, Wei-Li; Su, Jing; Bross, David H.; Peterson, Kirk A.; Wang, Lai-Sheng; Li, Jun

    2016-02-01

    The observation of the gaseous UFO- anion is reported, which is investigated using photoelectron spectroscopy and relativisitic ab initio calculations. Two strong photoelectron bands are observed at low binding energies due to electron detachment from the U-7sσ orbital. Numerous weak detachment bands are also observed due to the strongly correlated U-5f electrons. The electron affinity of UFO is measured to be 1.27(3) eV. High-level relativistic quantum chemical calculations have been carried out on the ground state and many low-lying excited states of UFO to help interpret the photoelectron spectra and understand the electronic structure of UFO. The ground state of UFO- is linear with an O-U-F structure and a 3H4 spectral term derived from a U 7sσ25fφ15fδ1 electron configuration, whereas the ground state of neutral UFO has a 4H7/2 spectral term with a U 7sσ15fφ15fδ1 electron configuration. Strong electron correlation effects are found in both the anionic and neutral electronic configurations. In the UFO neutral, a high density of electronic states with strong configuration mixing is observed in most of the scalar relativistic and spin-orbit coupled states. The strong electron correlation, state mixing, and spin-orbit coupling of the electronic states make the excited states of UFO very challenging for accurate quantum chemical calculations.

  19. Detection of irradiation treatment in crustacea by electron spin resonance (ESR) spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Stewart, E.M. [Queen`s Univ., Belfast, Northern Ireland (United Kingdom). Dept. of Food Science; Stevenson, M.H. [Queen`s Univ., Belfast, Northern Ireland (United Kingdom). Dept. of Food Science]|[Department of Agriculture for Northern Ireland, Belfast (United Kingdom); Gray, R. [Department of Agriculture for Northern Ireland, Belfast (United Kingdom)

    1996-12-31

    When the Food (Control of Irradiation) Regulations 1990 came into force in the United Kingdom in January 1991 they included provision for the irradiation of Crustacea to an overall average dose of 3 kGy. The treatment of Crustacea with ionising radiation would reduce numbers of potential pathogens and spoilage organisms thus giving a microbiologically safer product with a longer shelf-life at chill temperatures. At present the process is being used in countries such as France and The Netherlands for the decontamination/shelf-life extension of shrimp. Therefore, as for other food products such as poultry, liquid whole egg and fruit, which are also treated with ionising radiation, it is desirable that a suitable test should be available to help in the control of the irradiation process. One such detection method which has been applied to irradiated Crustacea is that of electron spin resonance (ESR) spectroscopy due to the fact that the rigid exoskeleton has a relatively high dry matter so free radicals produced by ionising irradiation can be trapped and are, therefore, sufficiently stable to be detected. (author).

  20. Detection of irradiation treatment in crustacea by electron spin resonance (ESR) spectroscopy

    International Nuclear Information System (INIS)

    Stewart, E.M.; Gray, R.

    1996-01-01

    When the Food (Control of Irradiation) Regulations 1990 came into force in the United Kingdom in January 1991 they included provision for the irradiation of Crustacea to an overall average dose of 3 kGy. The treatment of Crustacea with ionising radiation would reduce numbers of potential pathogens and spoilage organisms thus giving a microbiologically safer product with a longer shelf-life at chill temperatures. At present the process is being used in countries such as France and The Netherlands for the decontamination/shelf-life extension of shrimp. Therefore, as for other food products such as poultry, liquid whole egg and fruit, which are also treated with ionising radiation, it is desirable that a suitable test should be available to help in the control of the irradiation process. One such detection method which has been applied to irradiated Crustacea is that of electron spin resonance (ESR) spectroscopy due to the fact that the rigid exoskeleton has a relatively high dry matter so free radicals produced by ionising irradiation can be trapped and are, therefore, sufficiently stable to be detected. (author)

  1. Ballistic Electron Emission Microscopy/Spectroscopy on Au/Titanylphthalocyanine/GaAs Heterostructures

    International Nuclear Information System (INIS)

    Oezcan, S; Roch, T; Strasser, G; Smoliner, J; Franke, R; Fritz, T

    2007-01-01

    In this article Au/titanylphthalocyanine/GaAs diodes incorporating ultra smooth thin films of the archetypal organic semiconductor titanylphthalocyanine (TiOPc) were investigated by Ballistic Electron Emission Microscopy/Spectroscopy (BEEM/S). Analyzing the BEEM spectra, we find that the TiOPc increases the BEEM threshold voltage compared to reference Au/GaAs diodes. From BEEM images taken we conclude that our molecular beam epitaxial (MBE) grown samples show very homogeneous transmission, compare to wet chemically manufactured organic films. The barrier height measured on the Au- TiOPc-GaAs is V b ∼ 1.2eV, which is in good agreement with the data found in [T. Nishi, K. Tanai, Y. Cuchi, M. R. Willis, and K. Seki Chem. Phys. Lett., vol. 414, pp. 479-482, 2005.]. The results indicate that TiOPc functions as a p-type semiconductor, which is plausible since the measurements were carried out in air [K. Walzer, T. Toccoli, A. Pallaori, R. Verucchi, T. Fritz, K. Leo, A. Boschetti, and S. Iannotte Surf. Scie., vol. 573, pp. 346-358, 2004

  2. ESR (Electronic Spin Resonance Spectroscopy) study of irradiated paper for biomedical material wrapping

    International Nuclear Information System (INIS)

    Huarte, Monica; Rubin de Celis, Emilio; Kairiyama, Eulogia; Zapata, Miguel; Santoro, Natalia; Magnavacca, Cecilia

    2009-01-01

    Ionising radiation treatments are used for sterilization, microbiological decontamination, disinfection, insect disinfestation and food preservation. This ionising radiation generates free radicals (FR) in matter, which can be detected by Electronic Spin Resonance Spectroscopy (ESR). For this work it had analysed different kind of irradiated package papers of syringes, surgical gloves and dressings by ESR. These were irradiated with doses between 20 and 35 kGy of gamma radiation (Cobalt 60). The processed samples were measured in a Bruker ECS 106 spectrometer. The obtained results were: 1-) The irritated samples showed a central peak and two satellites induced by the applied radiation; 2-) The non-irradiated samples did not show the characteristic satellite peaks of the irritated ones; 3-) A linear relationship between the signal heights per unit mass and the applied doses was found; and 4-) The signals were highly stable, with half-time values between 240 and 370 days for 20 and 30 kGy, permitting more than one year of monitoring proceedings. In conclusion, the ESR allows the detection, quantification and time monitoring processes of this kind of irradiated materials. (author) [es

  3. Terahertz imaging and spectroscopy based on hot electron bolometer (HEB) heterodyne detection

    Science.gov (United States)

    Gerecht, Eyal; You, Lixing

    2008-02-01

    Imaging and spectroscopy at terahertz frequencies have great potential for healthcare, plasma diagnostics, and homeland security applications. Terahertz frequencies correspond to energy level transitions of important molecules in biology and astrophysics. Terahertz radiation (T-rays) can penetrate clothing and, to some extent, can also penetrate biological materials. Because of their shorter wavelengths, they offer higher spatial resolution than do microwaves or millimeter waves. We are developing hot electron bolometer (HEB) mixer receivers for heterodyne detection at terahertz frequencies. HEB detectors provide unprecedented sensitivity and spectral resolution at terahertz frequencies. We describe the development of a two-pixel focal plane array (FPA) based on HEB technology. Furthermore, we have demonstrated a fully automated, two-dimensional scanning, passive imaging system based on our HEB technology operating at 0.85 THz. Our high spectral resolution terahertz imager has a total system noise equivalent temperature difference (NEΔT) value of better than 0.5 K and a spatial resolution of a few millimeters. HEB technology is becoming the basis for advanced terahertz imaging and spectroscopic technologies for the study of biological and chemical agents over the entire terahertz spectrum.

  4. Estimation of the absorbed dose in gamma irradiated food containing bone by electron spin resonance spectroscopy

    International Nuclear Information System (INIS)

    Basfar, A.A.; Abdel Rehim, F.

    1997-01-01

    The use of electron spin resonance (ESR) spectroscopy to accurately evaluate the absorbed dose to radiationprocessed bones (and thus meats) is examined. The exposure of foodstuffs containing bone to a dose of ionizing radiation results in the formation of long lived free radicals which give rise to characteristics ESR signals. The yield of radicals was found to be proportional to absorbed dose. Additive re-irradiation of previously irradiated bone was used to estimate the absorbed dose in the irradiated chicken bone. Simple non-linear rational equation was found to fit to the data and yields good dose estimates for irradiated bone in the range of doses (1.0 - 5.0 kGy). Decay of the ESR signal intensity was monitored at different dose levels (2.0 and 7.0 kGy) up to 22 days. The absorbed dose in irradiated chicken (2.Om 3.0 and 6.0 kGy) was assessed at 2, 6 and 12 days after irradiation. Relatively good results were obtained when measurements were made within the following days (up to 12 days) after irradiation. The ability of the dose additive method to provide accurate dose assessments is tested here

  5. Detecting Fermi-level shifts by Auger electron spectroscopy in Si and GaAs

    Science.gov (United States)

    Debehets, J.; Homm, P.; Menghini, M.; Chambers, S. A.; Marchiori, C.; Heyns, M.; Locquet, J. P.; Seo, J. W.

    2018-05-01

    In this paper, changes in surface Fermi-level of Si and GaAs, caused by doping and cleaning, are investigated by Auger electron spectroscopy. Based on the Auger voltage contrast, we compared the Auger transition peak energy but with higher accuracy by using a more accurate analyzer and an improved peak position determination method. For silicon, a peak shift as large as 0.46 eV was detected when comparing a cleaned p-type and n-type wafer, which corresponds rather well with the theoretical difference in Fermi-levels. If no cleaning was applied, the peak position did not differ significantly for both wafer types, indicating Fermi-level pinning in the band gap. For GaAs, peak shifts were detected after cleaning with HF and (NH4)2S-solutions in an inert atmosphere (N2-gas). Although the (NH4)2S-cleaning in N2 is very efficient in removing the oxygen from the surface, the observed Ga- and As-peak shifts are smaller than those obtained after the HF-cleaning. It is shown that the magnitude of the shift is related to the surface composition. After Si-deposition on the (NH4)2S-cleaned surface, the Fermi-level shifts back to a similar position as observed for an as-received wafer, indicating that this combination is not successful in unpinning the Fermi-level of GaAs.

  6. The study of x-ray photo-electron spectroscopy of 99mTc-RBC

    International Nuclear Information System (INIS)

    Song Chunyi

    1994-01-01

    99m Tc-RBC are widely used as visualization agents for a blood pool. In this research 99m Tc-RBC was prepared by in vivo labeling. The chemical state and changes of 99m Tc atoms in 99m Tc-RBC was determined by x-ray photo-electron spectroscopy (XPS). The stability of 99m Tc-RBC is best shown by the determination of XPS at one hour or at two hours after labeling. There are two ways of coordination of bonding of RBC and 99m Tc: One is the coordination of 99m Tc with the oxygen atom which carries a negative charge of the carboxyl radical on the polypeptide bond, the other is the coordination of 99m Tc with a sulfur atom which caries the negative charge of cysteine. From the E b value of 99m Tc-RBC 99m Tc 3d5/2, it can be inferred that 99m Tc of 99m Tc-RBC is less than a trivalent. At the same time, the results of the determination by XPS with the compounds containing 99 TcO 4 - , 99 Tc(V), 99 Tc(IV) and 99 Tc(III) show that the chemical shift is lowered as the reduction state is lowered. Experimental results coincide with theoretical inferences

  7. New method to measure the carbamoylating activity of nitrosoureas by electron paramagnetic resonance spectroscopy.

    Science.gov (United States)

    Gadzheva, V; Ichimori, K; Raikov, Z; Nakazawa, H

    1997-08-01

    A new method for measuring the carbamoylating activity of nitrosoureas and isocyanates using electron paramagnetic resonance (EPR) spectroscopy is described. The extent and time course of carbamoylation reaction of chloroethyl isocyanate and a series of 9 nitrosoureas toward amino group of 4-amino-2,2,6,6-tetramethyl-piperidine-1-oxyl were examined with both the EPR method and the HPLC method which has been proposed by Brubaker et al. [Biochem. Pharmacol. 35:2359 (1986)]. Spin-labeled nitrosoureas we synthesized are included in this study since they have less toxicity or more efficiency than commercially available drug in some cases. The concentration of carbamoylated product was easily determined with the EPR spectra. There is a very high correlation (r = 0.982, t = 2.58, N = 10, p nitrosoureas showed lower carbamoylating activity than non-labeled analogues. The carbamoylating activity for these nitrosourea depended on the reactivity of isocyanate intermediate and almost independent of their half life. This rapid and simple EPR method is suitable for the detailed investigation of the rate and extent of carbamoylation reaction.

  8. Ultrafast optical pump terahertz-probe spectroscopy of strongly correlated electron materials

    International Nuclear Information System (INIS)

    Averitt, R.D.; Taylor, Antoinette J.; Thorsmolle, V.K.; Jia, Quanxi; Lobad, A.I.; Trugman, S.A.

    2001-01-01

    We have used optical-pump far-infrared probe spectroscopy to probe the low energy electron dynamics of high temperature superconductors and colossal magnetoresistance manganites. For the superconductor YBa2Cu3O7, picosecond conductivity measurements probe the interplay between Cooper-pairs and quasiparticles. In optimally doped films, the recovery time for long-range phase-coherent pairing increases from ∼1.5 ps at 4K to ∼3.5 ps near Tc, consistent with the closing of the superconducting gap. For underdoped films, the measured recovery time is temperature independent (3.5 ps) in accordance with the presence of a pseudogap. Ultrafast picosecond measurements of optically induced changes in the absolute conductivity of La0:7M0:3MnO3 thin films (M = Ca, Sr) from 10K to ∼0.9Tc reveal a two-component relaxation. A fast, ∼2 ps, conductivity decrease arises from optically induced modification of the effective phonon temperature. The slower component, related to spin-lattice relaxation, has a lifetime that increases upon approaching Tc from below in accordance with an increasing spin specific heat. Our results indicate that for T<< Tc, the conductivity is determined by incoherent phonons while spin fluctuations dominate near Tc.

  9. Study of Electron-Pair Spectroscopy in Pb-Pb Collisions at LHC

    CERN Document Server

    CERN. Geneva

    1993-01-01

    Among observables that have been proposed as signals of quark gluon plasma the lepton pairs from decays of vector bosons r, w, j, J/Y, U,... play important role. Effects such as the J/Y suppression, chiral symmetry restoration, strangeness enhancement and fast "clock" for the fireball lifetime are associated with possibilities of the lepton-pair spectroscopy in PbPb collisions at the LHC energies. In PbPb collisions the high particle density in central rapidity region is expected and therefore one has first of all to verify the feasibility of experiments aimed to measurement of cross sections, width and positions of vector resonances. For this purpose the programme LHCWPT has been developed which simulates production and two-and three-body decays of the ¹¡, h°, h, r, w, f, J/Y, U and Drell-Yan pairs in central rapidity region and also a detection of electrons and positrons in HEAVY ION DEDICATED EXPERIMENT.

  10. Deep levels in as-grown and electron-irradiated n-type GaN studied by deep level transient spectroscopy and minority carrier transient spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Duc, Tran Thien [Department of Physics, Chemistry and Biology (IFM), Linköping University, S-581 83 Linköping (Sweden); School of Engineering Physics, Hanoi University of Science and Technology, 1 Dai Co Viet Road, Hanoi (Viet Nam); Pozina, Galia; Son, Nguyen Tien; Kordina, Olof; Janzén, Erik; Hemmingsson, Carl [Department of Physics, Chemistry and Biology (IFM), Linköping University, S-581 83 Linköping (Sweden); Ohshima, Takeshi [Japan Atomic Energy Agency (JAEA), Takasaki, Gunma 370-1292 (Japan)

    2016-03-07

    Development of high performance GaN-based devices is strongly dependent on the possibility to control and understand defects in material. Important information about deep level defects is obtained by deep level transient spectroscopy and minority carrier transient spectroscopy on as-grown and electron irradiated n-type bulk GaN with low threading dislocation density produced by halide vapor phase epitaxy. One hole trap labelled H1 (E{sub V} + 0.34 eV) has been detected on as-grown GaN sample. After 2 MeV electron irradiation, the concentration of H1 increases and at fluences higher than 5 × 10{sup 14 }cm{sup −2}, a second hole trap labelled H2 is observed. Simultaneously, the concentration of two electron traps, labelled T1 (E{sub C} – 0.12 eV) and T2 (E{sub C} – 0.23 eV), increases. By studying the increase of the defect concentration versus electron irradiation fluence, the introduction rate of T1 and T2 using 2 MeV- electrons was determined to be 7 × 10{sup −3 }cm{sup −1} and 0.9 cm{sup −1}, respectively. Due to the low introduction rate of T1, it is suggested that the defect is associated with a complex. The high introduction rate of trap H1 and T2 suggests that the defects are associated with primary intrinsic defects or complexes. Some deep levels previously observed in irradiated GaN layers with higher threading dislocation densities are not detected in present investigation. It is therefore suggested that the absent traps may be related to primary defects segregated around dislocations.

  11. Alpha and conversion electron spectroscopy of {sup 238,239}Pu and {sup 241}Am and alpha-conversion electron coincidence measurements

    Energy Technology Data Exchange (ETDEWEB)

    Dion, Michael P., E-mail: michael.dion@pnnl.gov; Miller, Brian W.; Warren, Glen A.

    2016-09-11

    A technique to determine the isotopic constituents of a mixed actinide sample has been proposed by a coincident alpha-conversion electron measurement. This presents a unique signature to allow the unfolding of isotopes that possess overlapping alpha particle energy and reduce backgrounds of an unseparated sample. The work presented here are results of conversion electron spectroscopy of {sup 241}Am, {sup 238}Pu and {sup 239}Pu using a dual-stage peltier-cooled 25 mm{sup 2} silicon drift detector and alpha spectroscopy with a passivated ion implanted planar silicon detector. The conversion electron spectra were evaluated from 20–55 keV based on fits to the dominant conversion electron emissions, which allowed the relative conversion electron emission intensities to be determined. These measurements provide crucial singles spectral information and calibration to aid in the coincident measurement approach. Furthermore, an alpha-conversion electron spectrometer was assembled using the silicon based detectors described and results of a coincident spectrum analysis is reported for {sup 241}Am.

  12. Highly effective portable beta spectrometer for precise depth selective electron Moessbauer spectroscopy

    International Nuclear Information System (INIS)

    Aldiyarov, N.U.; Kadyrzhanov, K.K.; Seytimbetov, A.M.; Zhdanov, V.S.

    2007-01-01

    Full text: More broad application of the nuclear-physical method of precise Depth Selective Electron Moessbauer Spectroscopy (DS EMS) is limited by insufficient accessibility of highly-effective beta spectrometers with acceptable resolution. It should be mentioned that the method DS EMS is realized at a combined installation that consists of a highly-effective beta spectrometer and a conventional portable nuclear gamma-resonance spectrometer. Yet few available beta spectrometers have sophisticated design and controlling; in most cases they are cumbersome. All the attempts to simplify beta spectrometers resulted in noticeable worsening of depth resolution for the DS EMS method making the measurements non precise. There is currently an obvious need in a highly-effective portable easily controlled beta spectrometer. While developing such portable beta spectrometer, it is more promising to use as basis a simpler spectrometer, which has ratio of sample size to spectrometer size of about five times. The paper presents an equal-arm version of a highly-effective portable beta spectrometer with transverse heterogeneous sector magnetic field that assures double focusing. The spectrometer is equipped with a large-area non-equipotential source (a sample under investigation) and a position-sensitive detector. This portable spectrometer meets all requirements for achievement of the DS EMS depth resolution close to the physical limit and demonstrates the following main characteristics: equilibrium orbit radius ρ 0 = 80 mm, instrumental energy resolution 0.6 % at solid angle 1 % of 4π steradian, area of non-equipotential source ∼ 80 mm 2 , registration by position-sensitive detector of ∼ 10 % of the energy interval. Highly-effective portable beta spectrometer assures obtaining Moessbauer data with depth resolution close to physical limit of the DS EMS method. So in measurements at conversion and Auger electrons with energies of about units of keV and above, the achieved

  13. Reflection-time-of-flight spectrometer for two-electron (e,2e) coincidence spectroscopy on surfaces

    International Nuclear Information System (INIS)

    Kirschner, J.; Kerherve, G.; Winkler, C.

    2008-01-01

    In this article, a novel time-of-flight spectrometer for two-electron-emission (e,2e/γ,2e) correlation spectroscopy from surfaces at low electron energies is presented. The spectrometer consists of electron optics that collect emitted electrons over a solid angle of approximately 1 sr and focus them onto a multichannel plate using a reflection technique. The flight time of an electron with kinetic energy of E kin ≅25 eV is around 100 ns. The corresponding time- and energy resolution are typically ≅1 ns and ≅0.65 eV, respectively. The first (e,2e) data obtained with the present setup from a LiF film are presented

  14. Detection of reactive oxygen species in isolated, perfused lungs by electron spin resonance spectroscopy

    Directory of Open Access Journals (Sweden)

    Schudt Christian

    2005-07-01

    Full Text Available Abstract Background The sources and measurement of reactive oxygen species (ROS in intact organs are largely unresolved. This may be related to methodological problems associated with the techniques currently employed for ROS detection. Electron spin resonance (ESR with spin trapping is a specific method for ROS detection, and may address some these technical problems. Methods We have established a protocol for the measurement of intravascular ROS release from isolated buffer-perfused and ventilated rabbit and mouse lungs, combining lung perfusion with the spin probe l-hydroxy-3-carboxy-2,2,5,5-tetramethylpyrrolidine (CPH and ESR spectroscopy. We then employed this technique to characterize hypoxia-dependent ROS release, with specific attention paid to NADPH oxidase-dependent superoxide formation as a possible vasoconstrictor pathway. Results While perfusing lungs with CPH over a range of inspired oxygen concentrations (1–21 %, the rate of CP• formation exhibited an oxygen-dependence, with a minimum at 2.5 % O2. Addition of superoxide dismutase (SOD to the buffer fluid illustrated that a minor proportion of this intravascular ROS leak was attributable to superoxide. Stimulation of the lungs by injection of phorbol-12-myristate-13-acetate (PMA into the pulmonary artery caused a rapid increase in CP• formation, concomitant with pulmonary vasoconstriction. Both the PMA-induced CPH oxidation and the vasoconstrictor response were largely suppressed by SOD. When the PMA challenge was performed at different oxygen concentrations, maximum superoxide liberation and pulmonary vasoconstriction occurred at 5 % O2. Using a NADPH oxidase inhibitor and NADPH-oxidase deficient mice, we illustrated that the PMA-induced superoxide release was attributable to the stimulation of NADPH oxidases. Conclusion The perfusion of isolated lungs with CPH is suitable for detection of intravascular ROS release by ESR spectroscopy. We employed this technique to

  15. Electronic energy states of HfSe/sub 2/ and NbSe/sub 2/ by low energy electron loss spectroscopy study

    Energy Technology Data Exchange (ETDEWEB)

    Ito, T; Iwami, M; Hiraki, A [Osaka Univ., Suita (Japan). Faculty of Engineering

    1981-06-01

    Low energy electron loss spectroscopy (ELS) study was performed on 1T-HfSe/sub 2/ (group IVB metal compound) and 2H-NbSe/sub 2/ (group VB metal compound) by using incident electron energies of 30-250 eV. From the loss data in the second derivative form, maxima in density-of-states in the conduction band of the compounds were deduced through the information on the filled core states by X-ray photoelectron spectroscopy. The conduction band of the transition-metal dichalcogenides could be divided into two parts. The results are discussed in relation to the previous work on WS/sub 2/ (group VIB metal compound), and also to proposals based on band calculations and experimental studies on the transition-metal dichalcogenides with constituent metals of group IVB, VB and VIB.

  16. On the investigation of electronic defect states in ZnO thin films by space charge spectroscopy with optical excitation

    Science.gov (United States)

    Schmidt, Matthias; Wenckstern, Holger von; Pickenhain, Rainer; Grundmann, Marius

    2012-09-01

    Electronic defect states in a n-type conducting zinc oxide thin film sample were investigated by means of space charge spectroscopy focussing on levels in the midgap region as well as on hole traps. To overcome the experimental difficulties arising from the wide bandgap and the lack of p-type conduction, optical excitation was employed to measure the emission of trapped charge carriers from these levels. Therefore - besides deep-level transient spectroscopy measurements - photo-capacitance, optically chopped photo-current, minority carrier transient spectroscopy, and optical capacitance-voltage experiments were conducted. In doing so, a midgap level labelled T4, and hole traps labelled TH1 and TH2 were detected. In the case of T4 and TH1 the photo-ionisation cross-section spectra were determined.

  17. Characterization of vacancy type defects in Electronic Materials by Positron Lifetime and Age-Momentum Correlation Spectroscopy

    Science.gov (United States)

    Suzuki, Ryoichi; Ohdaira, Toshiyuki

    2002-03-01

    Positron annihilation spectroscopy is known to be sensitive to vacancy type defects. At the National Institute of Advanced Industrial Science and Technology (AIST) Japan, the authors have developed a measurement system which enables us to perform depth-selective positron annihilation lifetime spectroscopy (PALS) and positron age-momentum correlation (AMOC) spectroscopy with an intense slow positron beam. PALS gives us information on the size of vacancies whereas AMOC gives us information on not only vacancy sizes but also impurities or chemical environments. Using this system, we have carried out defect characterization experiments on various electronic materials, e.g. ion implanted Si, SiO2/Si, MOS, CVD or SOD (spin-on-dielectric) grown low dielectric insulator films, etc.

  18. Effect of relaxation and decay of a charge transfer shakeup satellite on Auger-electron spectroscopy spectra and Auger-photoelectron coincidence spectroscopy spectra of adsorbates

    International Nuclear Information System (INIS)

    Ohno, Masahide

    2008-01-01

    An electron excited to an unoccupied part of adsorbate-substrate hybrid states in a chemisorbed molecule by a resonant core electron excitation or charge transfer (CT) shakeup may delocalize on time scale of core-hole decay so that the excited core-hole state relaxes partly or completely to a fully relaxed one. The Auger decay of the fully relaxed core-hole state via the relaxation of the excited one introduces an additional feature in the resonant Auger-electron spectroscopy (RAES) spectrum and the AES spectrum. However, the additional feature in the RAES spectrum is a normal AES spectrum by decay of the fully relaxed core-hole state, whereas the one in the AES spectrum is the AES spectrum by decay of the fully relaxed core-hole state broadened by the photoelectron spectroscopy (PES) CT shakeup satellite weighted by the branching ratio of the relaxation width. The discrepancies between the AES spectrum measured at high above the ionization threshold and the additional feature in the RAES spectrum consist of the symmetric-like part by the decay of the fully relaxed core-hole state via the relaxation of the CT shakeup state and the asymmetric part by the direct decay of the shakeup states. The asymmetric part increases with a decrease in the hybridization strength. This explains the variation with the hybridization strength in the discrepancies between the RAES spectra and the AES spectra of chemisorbed molecules such as CO/Ni, CO/Cu and CO/Ag. A comparison of the singles PES spectrum with the one measured in coincidence with the AES main line of a selected kinetic energy (KE) provides the delocalization rate of the excited electron in the CT shakeup state as a function of photoelectron KE. The coincidence measurement to obtain the partial singles PES spectrum is discussed

  19. Analytical electron microscope based on scanning transmission electron microscope with wavelength dispersive x-ray spectroscopy to realize highly sensitive elemental imaging especially for light elements

    International Nuclear Information System (INIS)

    Koguchi, Masanari; Tsuneta, Ruriko; Anan, Yoshihiro; Nakamae, Koji

    2017-01-01

    An analytical electron microscope based on the scanning transmission electron microscope with wavelength dispersive x-ray spectroscopy (STEM-WDX) to realize highly sensitive elemental imaging especially for light elements has been developed. In this study, a large-solid-angle multi-capillary x-rays lens with a focal length of 5 mm, long-time data acquisition (e.g. longer than 26 h), and a drift-free system made it possible to visualize boron-dopant images in a Si substrate at a detection limit of 0.2 atomic percent. (paper)

  20. SmB6 electron-phonon coupling constant from time- and angle-resolved photoelectron spectroscopy

    Science.gov (United States)

    Sterzi, A.; Crepaldi, A.; Cilento, F.; Manzoni, G.; Frantzeskakis, E.; Zacchigna, M.; van Heumen, E.; Huang, Y. K.; Golden, M. S.; Parmigiani, F.

    2016-08-01

    SmB6 is a mixed valence Kondo system resulting from the hybridization between localized f electrons and delocalized d electrons. We have investigated its out-of-equilibrium electron dynamics by means of time- and angle-resolved photoelectron spectroscopy. The transient electronic population above the Fermi level can be described by a time-dependent Fermi-Dirac distribution. By solving a two-temperature model that well reproduces the relaxation dynamics of the effective electronic temperature, we estimate the electron-phonon coupling constant λ to range from 0.13 ±0.03 to 0.04 ±0.01 . These extremes are obtained assuming a coupling of the electrons with either a phonon mode at 10 or 19 meV. A realistic value of the average phonon energy will give an actual value of λ within this range. Our results provide an experimental report on the material electron-phonon coupling, contributing to both the electronic transport and the macroscopic thermodynamic properties of SmB6.

  1. Vibrational Surface Electron-Energy-Loss Spectroscopy Probes Confined Surface-Phonon Modes

    Directory of Open Access Journals (Sweden)

    Hugo Lourenço-Martins

    2017-12-01

    Full Text Available Recently, two reports [Krivanek et al. Nature (London 514, 209 (2014NATUAS0028-083610.1038/nature13870, Lagos et al. Nature (London 543, 529 (2017NATUAS0028-083610.1038/nature21699] have demonstrated the amazing possibility to probe vibrational excitations from nanoparticles with a spatial resolution much smaller than the corresponding free-space phonon wavelength using electron-energy-loss spectroscopy (EELS. While Lagos et al. evidenced a strong spatial and spectral modulation of the EELS signal over a nanoparticle, Krivanek et al. did not. Here, we show that discrepancies among different EELS experiments as well as their relation to optical near- and far-field optical experiments [Dai et al. Science 343, 1125 (2014SCIEAS0036-807510.1126/science.1246833] can be understood by introducing the concept of confined bright and dark surface phonon modes, whose density of states is probed by EELS. Such a concise formalism is the vibrational counterpart of the broadly used formalism for localized surface plasmons [Ouyang and Isaacson Philos. Mag. B 60, 481 (1989PMABDJ1364-281210.1080/13642818908205921, García de Abajo and Aizpurua Phys. Rev. B 56, 15873 (1997PRBMDO0163-182910.1103/PhysRevB.56.15873, García de Abajo and Kociak Phys. Rev. Lett. 100, 106804 (2008PRLTAO0031-900710.1103/PhysRevLett.100.106804, Boudarham and Kociak Phys. Rev. B 85, 245447 (2012PRBMDO1098-012110.1103/PhysRevB.85.245447]; it makes it straightforward to predict or interpret phenomena already known for localized surface plasmons such as environment-related energy shifts or the possibility of 3D mapping of the related surface charge densities [Collins et al. ACS Photonics 2, 1628 (2015APCHD52330-402210.1021/acsphotonics.5b00421].

  2. Satellite structure of the xenon valence shell by electron momentum spectroscopy

    International Nuclear Information System (INIS)

    Braidwood, S.; Brunger, M.; Weigold, E.

    1992-05-01

    Momentum distributions and spectroscopic factors are obtained in a high resolution electron momentum spectroscopy (EMS) study of xenon at 1000 eV. The shapes and relative magnitudes of the momentum profiles are in excellent agreement with distorted-wave impulse approximations using the target Dirac-Fock approximation. The DWDF approximation accurately describes the relative magnitudes of the 5p and 5s manifold cross sections as well as the shape of the 5s cross section. The use of nonrelativistic Hartree-Fock wavefunctions gives significantly poorer fits to the data. Spectroscopic factors for transitions belonging to the 2 S e 1/2 ,P 0 1/2,3/2 , and 2 D 3 3/2,5/2 manifolds are assigned up to a separation energy of 45 eV. The spectroscopic strength for the lowest 5s transition is 0.345 ± 0.010 whereas that for the ground state 5p transition is 0.96 ± 0.02. The 5s strength in the continuum above 33.1 eV is 0.115 ± 0.025 and that for the 5p manifold is only 0.03± 0.01. The first momentum profiles belong to excited 2 P o and 2 D e manifolds are obtained. The latter, which must be entirely due to d-wave correlations in the xenon ground state, are in good agreement with DF 5d momentum profiles. Comparison is made with several many-body calculations and agreement with the latest relativistic calculation is very good. 26 refs., 3 tabs., 5 figs

  3. Electron spin resonance spectroscopy for immunoassay using iron oxide nanoparticles as probe.

    Science.gov (United States)

    Jiang, Jia; Tian, Sizhu; Wang, Kun; Wang, Yang; Zang, Shuang; Yu, Aimin; Zhang, Ziwei

    2018-02-01

    With the help of iron oxide nanoparticles, electron spin resonance spectroscopy (ESR) was applied to immunoassay. Iron oxide nanoparticles were used as the ESR probe in order to achieve an amplification of the signal resulting from the large amount of Fe 3+ ion enclosed in each nanoparticle. Rabbit IgG was used as antigen to test this method. Polyclonal antibody of rabbit IgG was used as antibody to detect the antigen. Iron oxide nanoparticle with a diameter of either 10 or 30 nm was labeled to the antibody, and Fe 3+ in the nanoparticle was probed for ESR signal. The sepharose beads were used as solid phase to which rabbit IgG was conjugated. The nanoparticle-labeled antibody was first added in the sample containing antigen, and the antigen-conjugated sepharose beads were then added into the sample. The nanoparticle-labeled antibody bound to the antigen on sepharose beads was separated from the sample by centrifugation and measured. We found that the detection ranges of the antigen obtained with nanoparticles of different sizes were different because the amount of antibody on nanoparticles of 10 nm was about one order of magnitude higher than that on nanoparticles of 30 nm. When 10 nm nanoparticle was used as probe, the upper limit of detection was 40.00 μg mL -1 , and the analytical sensitivity was 1.81 μg mL -1 . When 30 nm nanoparticle was used, the upper limit of detection was 3.00 μg mL -1 , and the sensitivity was 0.014 and 0.13 μg mL -1 depending on the ratio of nanoparticle to antibody. Graphical abstract Schematic diagram of procedure and ESR spectra.

  4. Correlated single-crystal electronic absorption spectroscopy and X-ray crystallography at NSLS beamline X26-C

    International Nuclear Information System (INIS)

    Orville, A.M.; Buono, R.; Cowan, M.; Heroux, A.; Shea-McCarthy, G.; Schneider, D.K.; Skinner, J.M.; Skinner, M.J.; Stoner-Ma, D.; Sweet, R.M.

    2011-01-01

    The research philosophy and new capabilities installed at NSLS beamline X26-C to support electronic absorption and Raman spectroscopies coupled with X-ray diffraction are reviewed. This beamline is dedicated full time to multidisciplinary studies with goals that include revealing the relationship between the electronic and atomic structures in macromolecules. The beamline instrumentation has been fully integrated such that optical absorption spectra and X-ray diffraction images are interlaced. Therefore, optical changes induced by X-ray exposure can be correlated with X-ray diffraction data collection. The installation of Raman spectroscopy into the beamline is also briefly reviewed. Data are now routinely generated almost simultaneously from three complementary types of experiments from the same sample. The beamline is available now to the NSLS general user population.

  5. Insights into the Structural Changes Occurring upon Photoconversion in the Orange Carotenoid Protein from Broadband Two-Dimensional Electronic Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    De Re, Eleonora; Schlau-Cohen, Gabriela S.; Leverenz, Ryan L.; Huxter, Vanessa M.; Oliver, Thomas A. A.; Mathies, Richard A.; Fleming, Graham R.

    2014-05-22

    Carotenoids play an essential role in photoprotection, interacting with other pigments to safely dissipate excess absorbed energy as heat. In cyanobacteria, the short time scale photoprotective mechanisms involve the photoactive orange carotenoid protein (OCP), which binds a single carbonyl carotenoid. Blue-green light induces the photoswitching of OCP from its ground state form (OCPO) to a metastable photoproduct (OCPR). OCPR can bind to the phycobilisome antenna and induce fluorescence quenching. The photoswitching is accompanied by structural and functional changes at the level of the protein and of the bound carotenoid. In this study, we use broadband two-dimensional electronic spectroscopy to look at the differences in excited state dynamics of the carotenoid in the two forms of OCP. Our results provide insight into the origin of the pronounced vibrational lineshape and oscillatory dynamics observed in linear absorption and 2D electronic spectroscopy of OCPO and the large inhomogeneous broadening in OCPR, with consequences for the chemical function of the two forms.

  6. FOREWORD: VI Workshop in Electron Volt Neutron Spectroscopy: Frontiers and Horizons

    Science.gov (United States)

    Seel, A. G.; Senesi, R.; Fernandez-Alonso, F.

    2014-12-01

    January 2014 saw the congregation in Abingdon (UK) of scientists from across the world, to discuss the current state and future of spectroscopy using epithermal neutrons. This meeting was the sixth in a series of workshops held in collaboration between the Science and Technology Facilities Council (UK) and the Consiglio Nazionale delle Ricerche (Italy), aimed at bringing together researchers with an interest in the use of electron-volt neutrons in spectroscopic studies [1]. This technique is termed Deep Inelastic Neutron Scattering (DINS), and also Neutron Compton Scattering (NCS) in reference to the analogy with Compton scattering of X-rays from electrons. In particular, this meeting centred jointly around experimentalists and theoreticians, formulating animated discussions as to the current overview of DINS and future horizons facing the field. The use of electron Volt neutrons for spectroscopic measurements dates back to the advent of proton-driven spallation neutron sources in the 1970s and 1980s. Following an initial scientific meeting in Los Alamos (USA) [2], the first two meetings in this series were held in Abingdon (UK) in 1995 and 1998, with subsequent meetings held in Santa Fe (USA) in 2005 [3], Oak Ridge National Laboratory (USA) in 2006 [4], and Rome, Italy; in 2010 [5]. The flagship instrument serving a continual user-programme for DINS measurements, and the main focus of this meeting, has been the VESUVIO spectrometer at ISIS [6, 7]. Subsequent instruments like SEQUOIA in the USA [8, 9] and a newer spectrometer in the Bariloche LINAC in Argentina [10, 11] have also been commissioned and began serving a growing user community. The availability of DINS measurements has extended the range of possible spectroscopic techniques that utilise neutrons into the kinematic region of high energy and momentum transfers, shown schematically in Figure 1. Spectroscopic instrument suites such as that of ISIS are thus able to probe processes on timescales across nine

  7. Investigation of Antioxidant Activity of Pomegranate Juices by Means of Electron Paramagnetic Resonance and UV-Vis Spectroscopy.

    Science.gov (United States)

    Kozik, Violetta; Jarzembek, Krystyna; Jędrzejowska, Agnieszka; Bąk, Andrzej; Polak, Justyna; Bartoszek, Mariola; Pytlakowska, Katarzyna

    2015-01-01

    Pomegranate fruit (Punica granatum L.) is a source of numerous phenolic compounds, and it contains flavonoids such as anthocyanins, anthocyanidins, cyanidins, catechins and other complexes of flavonoids, ellagitannins, and hydrolyzed tannins. Pomegranate juice shows antioxidant, antiproliferative, and anti-atherosclerotic properties. The antioxidant capacity (TEAC) of the pomegranate juices was measured using electron paramagnetic resonance (EPR) spectroscopy and 1,1-diphenyl-2-picrylhydrazyl (DPPH•) as a source of free radicals, and the total phenolic (TP) content was measured using UV-Vis spectroscopy. All the examined pomegranate juices exhibited relatively high antioxidant properties. The TEAC values determined by means of EPR spectroscopy using Trolox (TE) as a free radical scavenger were in the range of 463.12 to 1911.91 μmol TE/100 mL juice. The TP content measured by the Folin-Ciocalteu method, using gallic acid (GA) as a free radical scavenger, widely varied in the investigated pomegranate juice samples and ranged from 1673.62 to 5263.87 mg GA/1 L juice. The strongest antioxidant properties were observed with the fresh pomegranate juices obtained from the fruits originating from Israel, Lebanon, and Azerbaijan. Correlation analysis of numerical data obtained by means of EPR spectroscopy (TEAC) and UV-Vis spectroscopy (TP) gave correlation coefficient (r)=0.90 and determination coefficient (r2)=0.81 (P<0.05).

  8. Electronic structure of ferromagnetic semiconductor Ga1-xMnxAs probed by sub-gap magneto-optical spectroscopy

    OpenAIRE

    Acbas, G.; Kim, M. -H.; Cukr, M.; Novak, V.; Scarpulla, M. A.; Dubon, O. D.; Jungwirth, T.; Sinova, Jairo; Cerne, J.

    2009-01-01

    We employ Faraday and Kerr effect spectroscopy in the infrared range to investigate the electronic structure of Ga1-xMnxAs near the Fermi energy. The band structure of this archetypical dilute-moment ferromagnetic semiconductor has been a matter of controversy, fueled partly by previous measurements of the unpolarized infrared absorption and their phenomenological impurity-band interpretation. The infrared magneto-optical effects we study arise directly from the spin-splitting of the carrier ...

  9. Determination of the antiproton-to-electron mass ratio by precision laser spectroscopy of $\\overline{p}He^{+}$

    CERN Document Server

    Hori, M; Eades, John; Gomikawa, K; Hayano, R S; Ono, N; Pirkl, Werner; Widmann, E; Torii, H A; Juhász, B; Barna, D; Horváth, D

    2006-01-01

    A femtosecond optical frequency comb and continuous-wave pulse- amplified laser were used to measure 12 transition frequencies of antiprotonic helium to fractional precisions of (9-16) 10/sup -9lifetimes hitherto unaccessible to our precision laser spectroscopy method. Comparisons with three-body QED calculations yielded an antiproton-to-electron mass ratio of M/sub pmacron//m/sub e/=1836.152 674(5).

  10. Offline combination of pressurized fluid extraction and electron paramagnetic resonance spectroscopy for antioxidant activity of grape skin extracts assessment

    Czech Academy of Sciences Publication Activity Database

    Polovka, M.; Šťavíková, Lenka; Hohnová, Barbora; Karásek, Pavel; Roth, Michal

    2010-01-01

    Roč. 1217, č. 51 (2010), s. 7990-8000 ISSN 0021-9673 R&D Projects: GA ČR GA203/08/1536; GA MŠk LC06023 Institutional research plan: CEZ:AV0Z40310501 Keywords : pressurized fluid extraction * electron paramagnetic resonance spectroscopy * antioxidant activity Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 4.194, year: 2010

  11. Femtosecond X-ray magnetic circular dichroism absorption spectroscopy at an X-ray free electron laser

    Energy Technology Data Exchange (ETDEWEB)

    Higley, Daniel J., E-mail: dhigley@stanford.edu; Yuan, Edwin [SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025 (United States); Department of Applied Physics, Stanford University, Stanford, California 94305 (United States); Hirsch, Konstantin; Dakovski, Georgi L.; Jal, Emmanuelle; Lutman, Alberto A.; Coslovich, Giacomo; Hart, Philip; Hoffmann, Matthias C.; Mitra, Ankush; Moeller, Stefan; Ohldag, Hendrik; Seaberg, Matthew; Stöhr, Joachim; Nuhn, Heinz-Dieter; Reid, Alex H.; Dürr, Hermann A.; Schlotter, William F. [SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025 (United States); Liu, Tianmin; MacArthur, James P. [SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025 (United States); Department of Physics, Stanford University, Stanford, California 94305 (United States); and others

    2016-03-15

    X-ray magnetic circular dichroism spectroscopy using an X-ray free electron laser is demonstrated with spectra over the Fe L{sub 3,2}-edges. The high brightness of the X-ray free electron laser combined with high accuracy detection of incident and transmitted X-rays enables ultrafast X-ray magnetic circular dichroism studies of unprecedented sensitivity. This new capability is applied to a study of all-optical magnetic switching dynamics of Fe and Gd magnetic sublattices in a GdFeCo thin film above its magnetization compensation temperature.

  12. Time-resolved photoemission spectroscopy of electronic cooling and localization in CH3NH3PbI3 crystals

    Science.gov (United States)

    Chen, Zhesheng; Lee, Min-i.; Zhang, Zailan; Diab, Hiba; Garrot, Damien; Lédée, Ferdinand; Fertey, Pierre; Papalazarou, Evangelos; Marsi, Marino; Ponseca, Carlito; Deleporte, Emmanuelle; Tejeda, Antonio; Perfetti, Luca

    2017-09-01

    We measure the surface of CH3NH3PbI3 single crystals by making use of two-photon photoemission spectroscopy. Our method monitors the electronic distribution of photoexcited electrons, explicitly discriminating the initial thermalization from slower dynamical processes. The reported results disclose the fast-dissipation channels of hot carriers (0.25 ps), set an upper bound to the surface-induced recombination velocity (PbI3 samples is consistent with the progressive reduction of photoconversion efficiency in operating devices. Minimizing the density of shallow traps and solving the aging problem may boost the macroscopic efficiency of solar cells to the theoretical limit.

  13. Evidences from electron momentum spectroscopy for ultra-fast charge transfers and structural reorganizations in a floppy molecule: Ethanol

    International Nuclear Information System (INIS)

    Deleuze, Michael S; Hajgato, Balazs; Morini, Filippo

    2009-01-01

    Calculations of electron momentum distributions employing advanced Dyson orbital theories and statistical thermodynamics beyond the RRHO approximation fail to quantitatively reproduce the outermost momentum profile inferred from experiments on ethanol employing high resolution Electron Momentum Spectroscopy [1]. Study of the influence of nuclear dynamics in the initial ground state and final ionized state indicates that this discrepancy between theory and experiment reflects a charge transfer occurring during an ultra-fast dissociation of the ethanol radical cation into a methyl radical and H 2 C=O-H + .

  14. Theoretical study of molecular vibrations in electron momentum spectroscopy experiments on furan: An analytical versus a molecular dynamical approach

    International Nuclear Information System (INIS)

    Morini, Filippo; Deleuze, Michael S.; Watanabe, Noboru; Takahashi, Masahiko

    2015-01-01

    The influence of thermally induced nuclear dynamics (molecular vibrations) in the initial electronic ground state on the valence orbital momentum profiles of furan has been theoretically investigated using two different approaches. The first of these approaches employs the principles of Born-Oppenheimer molecular dynamics, whereas the so-called harmonic analytical quantum mechanical approach resorts to an analytical decomposition of contributions arising from quantized harmonic vibrational eigenstates. In spite of their intrinsic differences, the two approaches enable consistent insights into the electron momentum distributions inferred from new measurements employing electron momentum spectroscopy and an electron impact energy of 1.2 keV. Both approaches point out in particular an appreciable influence of a few specific molecular vibrations of A 1 symmetry on the 9a 1 momentum profile, which can be unravelled from considerations on the symmetry characteristics of orbitals and their energy spacing

  15. Hot electron and hole dynamics in thiol-capped CdSe quantum dots revealed by 2D electronic spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Lenngren, N.; Abdellah, M.A.; Zheng, K.; Al-Marri, M.J.; Zigmantas, D.; Žídek, Karel; Pullerits, T.

    2016-01-01

    Roč. 18, č. 37 (2016), s. 26199-26204 ISSN 1463-9076 Institutional support: RVO:61389021 Keywords : quantum dots (QDs) * two-dimesional coherent spectroscopy * carrier relaxation * carrier trapping Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 4.123, year: 2016

  16. A combined photoelectron spectroscopy and relativistic ab initio studies of the electronic structures of UFO and UFO(-).

    Science.gov (United States)

    Roy, Soumendra K; Jian, Tian; Lopez, Gary V; Li, Wei-Li; Su, Jing; Bross, David H; Peterson, Kirk A; Wang, Lai-Sheng; Li, Jun

    2016-02-28

    The observation of the gaseous UFO(-) anion is reported, which is investigated using photoelectron spectroscopy and relativisitic ab initio calculations. Two strong photoelectron bands are observed at low binding energies due to electron detachment from the U-7sσ orbital. Numerous weak detachment bands are also observed due to the strongly correlated U-5f electrons. The electron affinity of UFO is measured to be 1.27(3) eV. High-level relativistic quantum chemical calculations have been carried out on the ground state and many low-lying excited states of UFO to help interpret the photoelectron spectra and understand the electronic structure of UFO. The ground state of UFO(-) is linear with an O-U-F structure and a (3)H4 spectral term derived from a U 7sσ(2)5fφ(1)5fδ(1) electron configuration, whereas the ground state of neutral UFO has a (4)H(7/2) spectral term with a U 7sσ(1)5fφ(1)5fδ(1) electron configuration. Strong electron correlation effects are found in both the anionic and neutral electronic configurations. In the UFO neutral, a high density of electronic states with strong configuration mixing is observed in most of the scalar relativistic and spin-orbit coupled states. The strong electron correlation, state mixing, and spin-orbit coupling of the electronic states make the excited states of UFO very challenging for accurate quantum chemical calculations.

  17. Surface structure and analysis with scanning tunneling microscopy and electron tunneling spectroscopy

    International Nuclear Information System (INIS)

    Coleman, R.V.

    1992-01-01

    This report discusses the following topics: charge-density waves in layer structures; charge-density waves in linear chain compounds; spectroscopy with the STM; STM studies of oxides; and development of atomic force microscopy. (LSP)

  18. Interface electronic properties of co-evaporated MAPbI3 on ZnO(0001): In situ X-ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy study

    International Nuclear Information System (INIS)

    Zhou, Xianzhong; Li, Xiaoli; Huang, Feng; Zhong, Dingyong; Liu, Yuan

    2016-01-01

    In this work, the interface electronic properties of ZnO(0001)/CH 3 NH 3 PbI 3 were investigated by both X-ray and ultraviolet photoelectron spectroscopy. The CH 3 NH 3 PbI 3 thin films were grown on single crystalline ZnO(0001) substrate in situ by co-evaporation of PbI 2 and CH 3 NH 3 I at room temperature with various thickness from 1.5 nm to 190 nm. It was found that the conduction band minimum of ZnO lies 0.3 eV below that of CH 3 NH 3 PbI 3 , while the valence band maximum of ZnO lies 2.1 eV below that of CH 3 NH 3 PbI 3 , implying that the electrons can be effectively transported from CH 3 NH 3 PbI 3 to ZnO, and the holes can be blocked in the same time. A PbI 2 rich layer was initially formed at the interface of ZnO(0001)/CH 3 NH 3 PbI 3 during the growth. As a consequence, an interface barrier was built up which may prevent the electron transport at the interface.

  19. Vibrational and electronic spectroscopy of ion-implantation-induced defects in fused silica and crystalline quartz

    International Nuclear Information System (INIS)

    Arnold, G.W.

    1978-01-01

    Defects produced by implantation of various atomic species in fused and crystalline SiO 2 were studied using infrared reflection spectroscopy (IRS) with UV-visible spectroscopy. We observe a new vibrational band at 830 cm -1 which is tentatively associated with the creation of two nonbridging O atoms in SiO 4 units. Numerous chemical effects were also observed, including evidence for chemical incorporation of Li and anomalously large O-vacancy production for Al + , B + and Si + implantation

  20. Electronic structure of Mo1-x Re x alloys studied through resonant photoemission spectroscopy

    Science.gov (United States)

    Sundar, Shyam; Banik, Soma; Sharath Chandra, L. S.; Chattopadhyay, M. K.; Ganguli, Tapas; Lodha, G. S.; Pandey, Sudhir K.; Phase, D. M.; Roy, S. B.

    2016-08-01

    We studied the electronic structure of Mo-rich Mo1-x Re x alloys (0≤slant x≤slant 0.4 ) using valence band photoemission spectroscopy in the photon energy range 23-70 eV and density of states calculations. Comparison of the photoemission spectra with the density of states calculations suggests that, with respect to the Fermi level E F, the d states lie mostly in the binding energy range 0 to  -6 eV, whereas s states lie in the binding energy range  -4 to  -10 eV. We observed two resonances in the photoemission spectra of each sample, one at about 35 eV photon energy and the other at about 45 eV photon energy. Our analysis suggests that the resonance at 35 eV photon energy is related to the Mo 4p-5s transition and the resonance at 45 eV photon energy is related to the contribution from both the Mo 4p-4d transition (threshold: 42 eV) and the Re 5p-5d transition (threshold: 46 eV). In the constant initial state plot, the resonance at 35 eV incident photon energy for binding energy features in the range E F (BE  =  0) to  -5 eV becomes progressively less prominent with increasing Re concentration x and vanishes for x  >  0.2. The difference plots obtained by subtracting the valence band photoemission spectrum of Mo from that of Mo1-x Re x alloys, measured at 47 eV photon energy, reveal that the Re d-like states appear near E F when Re is alloyed with Mo. These results indicate that interband s-d interaction, which is weak in Mo, increases with increasing x and influences the nature of the superconductivity in alloys with higher x.

  1. Employing Electron Microscopy integrated with X-ray Spectroscopy for Kuntawa Landslide Assessment

    Science.gov (United States)

    Dikedi, P. N.

    2016-12-01

    This work centres on Kuntawa landslide assessment owing to the enigmatic nature of a 2003 landslide which buried 4 people and a truck in Kuntawa village, of Nigeria. A Phenom ProX Scanning Electron Microscope (SEM) integrated with Energy dispersive X-ray Spectroscopy (EDS) and Particlemetric software was employed to generate the morphology, particle size data, elemental identification data and topography (at 3500x) of earth samples scooped from the landslide site. For a core sample 1 at depth, d=3.75m, average circle equivalent diameter dav, area a and volume by area Va of 11.5 µm, 249 µm² and 3680µm³ were generated respectively; at d=3.785m, dav , a and Va of 6.19µm, 30.1µm² and 124µm³ were generated respectively; at d=3.82m, dav , a and Va of 11.5 µm, 130 µm² and 1380µm³ were generated respectively. For a core sample 2, at d=3.75m, dav, a and Va of 5.54 µm, 26 µm² and 108µm³ were generated respectively; at d=3.82m, dav , a and Va of 19.4µm, 338µm² and 5240µm³ were generated respectively; a total of 243 particles were scanned. One of the results from specific surface for samples 1 and 2, reveals that it would take twice and four times the amount of water needed to wet an entire surface both at d=3.82m than at d=3.785m and d=3.75m respectively. Additional laboratory facilities reveal that soil water content Š, volumetric water content Vwc, porosity Φ, soil water-filled pore space Wps, increased with increasing d; bulk density ρb, decreased with increasing d. Elemental composition at the landslide site were generated from the EDS: oxygen (O), Silicon (Si), Bromine (Br), iron (Fe), Carbon (C) and Aluminium (Al). O and C had the highest and lowest concentration of elemental compositions of 68.5% at 3.75m depth and 1% at 3.82m depth for samples 1 and 2, respectively. Keywords: EDS, Particlemetric, SEM.

  2. In-situ Transmission Electron Microscopy and Spectroscopy Studies of Interfaces in Li-ion Batteries: Challenges and Opportunities

    International Nuclear Information System (INIS)

    Wang, Chong M.; Xu, Wu; Liu, Jun; Choi, Daiwon; Arey, Bruce W.; Saraf, Laxmikant V.; Zhang, Jiguang; Yang, Zhenguo; Thevuthasan, Suntharampillai; Baer, Donald R.; Salmon, Norman

    2010-01-01

    The critical challenge facing the lithium ion battery development is the basic understanding of the structural evolution during the cyclic operation of the battery and the consequence of the structural evolution on the properties of the battery. Although transmission electron microscopy (TEM) and spectroscopy have been evolved to a stage such that it can be routinely used to probe into both the structural and chemical composition of the materials with a spatial resolution of a single atomic column, a direct in-situ TEM observation of structural evolution of the materials in lithium ion battery during the dynamic operation of the battery has never been reported. This is related to three factors: high vacuum operation of a TEM; electron transparency requirement of the region to be observed, and the difficulties dealing with the liquid electrolyte of lithium ion battery. In this paper, we report the results of exploring the in-situ TEM techniques for observation of the interface in lithium ion battery during the operation of the battery. A miniature battery was fabricated using a nanowire and an ionic liquid electrolyte. The structure and chemical composition of the interface across the anode and the electrolyte was studied using TEM imaging, electron diffraction, and electron energy loss spectroscopy. In addition, we also explored the possibilities of carrying out in-situ TEM studies of lithium ion batteries with a solid state electrolyte.

  3. Theoretical study of electronic absorption spectroscopy of propadienylidene molecule vis-â-vis the observed diffuse interstellar bands

    International Nuclear Information System (INIS)

    Reddy, Samala Nagaprasad; Mahapatra, S.

    2012-01-01

    Highlights: ► Theoretical study of spectroscopy and dynamics of electronically excited l-C 3 H 2 . ► Construction of ab initio electronic potential energy and diabatic coupling surfaces. ► First principles study of nuclear dynamics on excited electronic states. ► Findings reveal l-C 3 H 2 is a potential molecular carrier of diffuse interstellar bands. ► Electronically excited l-C 3 H 2 decays by ultrafast nonradiative internal conversion. -- Abstract: Observation of broad and diffuse interstellar bands (DIBs) at 4881 Å and 5440 Å assigned to the optical absorption spectrum of Y-shaped propadienylidene (H 2 C=C=C:) molecule is theoretically examined in this paper. This molecule apparently absorbs in the same wavelength region as the observed DIBs and was suggested to be a potential carrier of these DIBs. This assignment mostly relied on the experimental data from radioastronomy and laboratory measurements. Motivated by these available experimental data we attempt here a theoretical study and investigate the detailed electronic structure and nuclear dynamics underlying the electronic absorption bands of propadienylidene molecule. Our results show that this molecule indeed absorbs in the wavelength region of the recorded DIBs. Strong nonadiabatic coupling between its energetically low-lying electronic states plays major role, initiates ultrafast internal conversion and contributes to the spectral broadening. Theoretical findings are finally compared with the available experimental and theoretical data and discussed in connection with the recorded DIBs.

  4. Free electrons and ionic liquids: study of excited states by means of electron-energy loss spectroscopy and the density functional theory multireference configuration interaction method.

    Science.gov (United States)

    Regeta, Khrystyna; Bannwarth, Christoph; Grimme, Stefan; Allan, Michael

    2015-06-28

    The technique of low energy (0-30 eV) electron impact spectroscopy, originally developed for gas phase molecules, is applied to room temperature ionic liquids (IL). Electron energy loss (EEL) spectra recorded near threshold, by collecting 0-2 eV electrons, are largely continuous, assigned to excitation of a quasi-continuum of high overtones and combination vibrations of low-frequency modes. EEL spectra recorded by collecting 10 eV electrons show predominantly discrete vibrational and electronic bands. The vibrational energy-loss spectra correspond well to IR spectra except for a broadening (∼0.04 eV) caused by the liquid surroundings, and enhanced overtone activity indicating a contribution from resonant excitation mechanism. The spectra of four representative ILs were recorded in the energy range of electronic excitations and compared to density functional theory multireference configuration interaction (DFT/MRCI) calculations, with good agreement. The spectra up to about 8 eV are dominated by π-π* transitions of the aromatic cations. The lowest bands were identified as triplet states. The spectral region 2-8 eV was empty in the case of a cation without π orbitals. The EEL spectrum of a saturated solution of methylene green in an IL band showed the methylene green EEL band at 2 eV, indicating that ILs may be used as a host to study nonvolatile compounds by this technique in the future.

  5. X-ray photoelectron spectroscopy and Auger electron spectroscopy studies on the passivation behavior of plasma-nitrided low alloy steel in nitric acid

    Energy Technology Data Exchange (ETDEWEB)

    Chyou, S.D.; Shih, H.C. (Dept. of Materials Science and Engineering, National Tsing Hua Univ., Hsinchu (Taiwan))

    1991-12-14

    Nitrided SAE 4140 steel has been passivated by concentrated nitric acid. The resulting film was characterized using a combination of surface-analytical techniques, such as X-ray photoelectron spectroscopy (XPS) to evaluate the chemical composition of the passive film. Auger electron spectroscopy (AES) combined with ion etching was used to determine the composition depth profiles of nitrided surface. It was found that preferential dissolution of iron leads to enhanced nitrogen and chromium concentrations within the oxynitrided layer. A dense protective oxynitrided layer was found to be formed on the nitrided surface when the concentration of nitric acid was as high as 8 M. The results of X-ray diffraction, XPS and AES analyses conclude that the protective nitride layer is composed of (Fe,Cr){sub 4}N, (Fe,Cr){sub 2-3}N and CrN in the inner layer, Fe{sub 2}O{sub 3}, Cr{sub 2}O{sub 3} and remnant nitrides in the middle layer and nitrides accompanying Cr(OH){sub 3}.H{sub 2}O and {gamma}'-FeOOH in the outermost layer. (orig.).

  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)

    Zou, Y.; Wang, L.W.; Huang, N.K.

    2007-01-01

    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, TiH 2 , CH 3 , CH 4 , C 2 H 2 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. Electron-beam-induced reduction of Fe3+ in iron phosphate dihydrate, ferrihydrite, haemosiderin and ferritin as revealed by electron energy-loss spectroscopy

    International Nuclear Information System (INIS)

    Pan, Ying-Hsi; Vaughan, Gareth; Brydson, Rik; Bleloch, Andrew; Gass, Mhairi; Sader, Kasim; Brown, Andy

    2010-01-01

    The effect of high-energy electron irradiation on ferritin/haemosiderin cores (in an iron-overloaded human liver biopsy), its mineral analogue; six-line ferrihydrite (6LFh), and iron phosphate dihydrate (which has similar octahedral ferric iron to oxygen coordination to that in ferrihydrite and ferritin/haemosiderin cores) has been investigated using electron energy-loss spectroscopy (EELS). Fe L 2,3 -ionisation edges were recorded on two types of electron microscope: a 200 keV transmission electron microscope (TEM) and a 100 keV scanning transmission electron microscope (STEM), in order to investigate the damage mechanisms in operation and to establish a methodology for minimum specimen alteration during analytical electron microscopic characterisation. A specimen damage mechanism dominated by radiolysis that results in the preferential loss of iron co-ordinating ligands (O, OH and H 2 O) is discussed. The net result of irradiation is structural re-organisation and reduction of iron within the iron hydroxides. At sufficiently low electron fluence and particularly in the lower incident energy, finer probe diameter STEM, the alteration is shown to be minimal. All the materials examined exhibit damage which as a function of cumulative fluence is best fitted by an inverse power-law, implying that several chemical and structural changes occur in response to the electron beam and we suggest that these are governed by secondary processes arising from the primary ionisation event. This work affirms that electron fluence and current density should be considered when measuring mixed valence ratios with EELS.

  8. Electron-beam-induced reduction of Fe{sup 3+} in iron phosphate dihydrate, ferrihydrite, haemosiderin and ferritin as revealed by electron energy-loss spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Pan, Ying-Hsi; Vaughan, Gareth; Brydson, Rik [Institute for Materials Research, SPEME, University of Leeds, Leeds LS2 9JT (United Kingdom); Bleloch, Andrew; Gass, Mhairi [SuperSTEM, Daresbury Laboratories, Warrington WA4 4AD (United Kingdom); Sader, Kasim [Institute for Materials Research, SPEME, University of Leeds, Leeds LS2 9JT (United Kingdom); SuperSTEM, Daresbury Laboratories, Warrington WA4 4AD (United Kingdom); Brown, Andy, E-mail: a.p.brown@leeds.ac.uk [Institute for Materials Research, SPEME, University of Leeds, Leeds LS2 9JT (United Kingdom)

    2010-07-15

    The effect of high-energy electron irradiation on ferritin/haemosiderin cores (in an iron-overloaded human liver biopsy), its mineral analogue; six-line ferrihydrite (6LFh), and iron phosphate dihydrate (which has similar octahedral ferric iron to oxygen coordination to that in ferrihydrite and ferritin/haemosiderin cores) has been investigated using electron energy-loss spectroscopy (EELS). Fe L{sub 2,3}-ionisation edges were recorded on two types of electron microscope: a 200 keV transmission electron microscope (TEM) and a 100 keV scanning transmission electron microscope (STEM), in order to investigate the damage mechanisms in operation and to establish a methodology for minimum specimen alteration during analytical electron microscopic characterisation. A specimen damage mechanism dominated by radiolysis that results in the preferential loss of iron co-ordinating ligands (O, OH and H{sub 2}O) is discussed. The net result of irradiation is structural re-organisation and reduction of iron within the iron hydroxides. At sufficiently low electron fluence and particularly in the lower incident energy, finer probe diameter STEM, the alteration is shown to be minimal. All the materials examined exhibit damage which as a function of cumulative fluence is best fitted by an inverse power-law, implying that several chemical and structural changes occur in response to the electron beam and we suggest that these are governed by secondary processes arising from the primary ionisation event. This work affirms that electron fluence and current density should be considered when measuring mixed valence ratios with EELS.

  9. X-ray absorption spectroscopy using a self-seeded soft X-ray free-electron laser

    Energy Technology Data Exchange (ETDEWEB)

    Kroll, Thomas; Kern, Jan; Kubin, Markus; Ratner, Daniel; Gul, Sheraz; Fuller, Franklin D.; Löchel, Heike; Krzywinski, Jacek; Lutman, Alberto; Ding, Yuantao; Dakovski, Georgi L.; Moeller, Stefan; Turner, Joshua J.; Alonso-Mori, Roberto; Nordlund, Dennis L.; Rehanek, Jens; Weniger, Christian; Firsov, Alexander; Brzhezinskaya, Maria; Chatterjee, Ruchira; Lassalle-Kaiser, Benedikt; Sierra, Raymond G.; Laksmono, Hartawan; Hill, Ethan; Borovik, Andrew; Erko, Alexei; Föhlisch, Alexander; Mitzner, Rolf; Yachandra, Vittal K.; Yano, Junko; Wernet, Philippe; Bergmann, Uwe

    2016-01-01

    © 2016 Optical Society of America. X-ray free electron lasers (XFELs) enable unprecedented new ways to study the electronic structure and dynamics of transition metal systems. L-edge absorption spectroscopy is a powerful technique for such studies and the feasibility of this method at XFELs for solutions and solids has been demonstrated. However, the required x-ray bandwidth is an order of magnitude narrower than that of self-amplified spontaneous emission (SASE), and additional monochromatization is needed. Here we compare L-edge x-ray absorption spectroscopy (XAS) of a prototypical transition metal system based on monochromatizing the SASE radiation of the linac coherent light source (LCLS) with a new technique based on self-seeding of LCLS. We demonstrate how L-edge XAS can be performed using the self-seeding scheme without the need of an additional beam line monochromator. We show how the spectral shape and pulse energy depend on the undulator setup and how this affects the x-ray spectroscopy measurements.

  10. Many-body effect in the resonant Ti L23-M23V Auger-electron spectroscopy spectra and Auger-photoelectron coincidence spectroscopy spectra of Ti oxides

    International Nuclear Information System (INIS)

    Ohno, Masahide

    2007-01-01

    Recently Danger et al. [J. Danger, H. Magnan, D. Chandesris, P. Le Fevre, S. Bourgeois, J. Jupille, A. Verdini, R. Gotter, A. Morgante, Phys. Rev. B 64 (2001) 045110] and Le Fevre et al. [P. Le Fevre, J. Danger, H. Magnan, D. Chandesris, J. Jupille, S. Bourgeois, M.-A. Arrio, R. Gotter, A. Verdini, A. Morgante, Phys. Rev. B 69 (2004) 155421] showed the absence of resonant Raman scattering feature in the Ti L 23 -M 23 V resonant Auger-electron spectroscopy (RAES) spectra of Ti oxides measured across the Ti 2p edges. They attributed the absence to the covalent character of the Ti-O bond which allows an effective delocalization of 3d electrons. It is shown by a many-body theory that when the time scale of relaxation of the resonantly excited core-hole state to the fully relaxed core-hole state is much shorter than that of core-hole decay, any sizeable Raman scattering is absent in the RAES spectra measured across the Ti 2p edges. The relaxation width depends on the hybridization strength and the charge transfer (CT) energy between the two states. The L 2 -L 3 V Coster-Kronig (CK) decay widths of TiO 2 and TiO 2-x are determined from the L 23 -M 23 V Auger-photoelectron coincidence spectroscopy (APECS) spectra reported in the aforementioned papers. They are about 0.18 and 0.35 eV, respectively. The CK-decay width in the reduced Ti oxide increases compared to that of TiO 2 in rutile because of filling of the 3d states just below the Fermi level in the former

  11. New pbysical methods used in the study of composition, electronic properties and surface phenomena of solid substances. I. Electronic spectroscopies

    International Nuclear Information System (INIS)

    Toderean, A; Ilonca, Gh.

    1981-01-01

    The discovery of different kinds of interactions between solids and fotonic, respectively electronic and ionic beams, leads to the development of many new, very sensitive, physical methods for the study of solids. This monograph tries to present some of these methods, useful in compositional analysis, in the study of electronic properties and of the surface processes of solid substances. This is done from the point of view both of physical phenomena underlying them and of the information obtainable with such methods. But the whole monograph is limited only to the methods based on the electronic properties of the elements existing in the solid probes studied and this paper presents only those of them in which the detected beam is an electronic one, like: ELS, DAPS, ILS, AES, AEAPS, INS, TSS, XPS and UPS. (authors)

  12. Electronic structure of beta-FeSi sub 2 obtained by maximum entropy method and photoemission spectroscopy

    CERN Document Server

    Kakemoto, H; Makita, Y; Kino, Y; Tsukamoto, T; Shin, S; Wada, S; Tsurumi, T

    2003-01-01

    The electronic structure of beta-FeSi sub 2 was investigated by maximum entropy method (MEM) and photoemission spectroscopy. The electronic structure obtained by MEM using X-ray diffraction data at room temperature (RT) showed covalent bonds of Fe-Si and Si-Si electrons. The photoemission spectra of beta-FeSi sub 2 at RT were changed by incidence photon energies. For photon energies between 50 and 100 eV, resonant photoemission spectra caused by a super Coster-Kronig transition were observed. In order to reduce resonant effect about Fe(3d) for obtained photoemission spectra, difference spectrum between 53 and 57 eV was calculated, and it was compared with ab-initio band calculation and spectra function.

  13. Electronic structure of the Ga1-xCr xN studied by high-energy photoemission spectroscopy

    International Nuclear Information System (INIS)

    Kim, J.J.; Makino, H.; Yao, T.; Takata, Y.; Kobayashi, K.; Yamamoto, T.; Hanada, T.; Cho, M.W.; Ikenaga, E.; Yabashi, M.; Miwa, D.; Nishino, Y.; Tamasaku, K.; Ishikawa, T.; Shin, S.

    2005-01-01

    Valence band spectra of Ga 1-x Cr x N have been investigated by high-energy photoemission spectroscopy at the photon energy of 5.95 keV. Cr doping does introduce a novel electronic structure in the bandgap and causes some change in valence band structure. Based on the first-principle calculation, Cr-associated electronic levels in the bandgap are assigned to nonbonding and antibonding d states while the change of the valence band suggests that the Ga 4s originated states are significantly modified through hybridization with the Cr 3d orbital. The present result evidences that the Ga valence electrons are considerably modified through the interaction with the second nearest-neighbour Cr atoms

  14. Unoccupied electronic state of delafossite-type PdCoO2 single crystal probed using inverse photoemission spectroscopy

    International Nuclear Information System (INIS)

    Higuchi, Tohru; Tsukamoto, Takeyo; Hasegawa, Masashi; Tanaka, Masayuki; Takei, Humihiko; Shin, Shik

    2004-01-01

    The unoccupied electronic state of delafossite-type PdCoO 2 has been studied using inverse-photoemission spectroscopy (IPES). The Fermi edge and the unoccupied density-of-state (DOS) at the Fermi level (E F ) are not observed in the IPES spectrum measured at the incidence electron energy (E K ) of 100 eV, which corresponds to the Cooper minimum of Pd 4d. The finite DOS at E F is observed in the IPES spectra measured at the lower E K , which the ionization cross section of Pd 4d increases. These findings indicate that the Pd 4d electron is closely related to the low electrical resistivity of PdCoO 2 . (author)

  15. Supervised Mineral Classification with Semi-automatic Training and Validation Set Generation in Scanning Electron Microscope Energy Dispersive Spectroscopy Images of Thin Sections

    DEFF Research Database (Denmark)

    Flesche, Harald; Nielsen, Allan Aasbjerg; Larsen, Rasmus

    2000-01-01

    This paper addresses the problem of classifying minerals common in siliciclastic and carbonate rocks. Twelve chemical elements are mapped from thin sections by energy dispersive spectroscopy in a scanning electron microscope (SEM). Extensions to traditional multivariate statistical methods...

  16. Remarkably High Conversion Efficiency of Inverted Bulk Heterojunction Solar Cells: From Ultrafast Laser Spectroscopy and Electron Microscopy to Device Fabrication and Optimization

    KAUST Repository

    Alsulami, Qana; Banavoth, Murali; Alsinan, Yara; Parida, Manas R.; Aly, Shawkat Mohammede; Mohammed, Omar F.

    2016-01-01

    of these photophysical processes at device interfaces remains superficial, creating a major bottleneck that circumvents advancements and the optimization of these solar cells. Here, results from time-resolved laser spectroscopy and high-resolution electron microscopy

  17. Far-field interaction of focused relativistic electron beams in electron energy loss spectroscopy of nanoscopic platelets

    OpenAIRE

    Itskovsky, M. A.; Cohen, H.; Maniv, T.

    2008-01-01

    A quantum mechanical scattering theory for relativistic, highly focused electron beams near nanoscopic platelets is presented, revealing a new excitation mechanism due to the electron wave scattering from the platelet edges. Radiative electromagnetic excitations within the light cone are shown to arise, allowed by the breakdown of momentum conservation along the beam axis in the inelastic scattering process. Calculated for metallic (silver and gold) and insulating (SiO2 and MgO) nanoplatelets...

  18. Spectroscopy of highly charged tungsten ions with Electron Beam Ion Traps

    International Nuclear Information System (INIS)

    Sakaue, Hiroyuki A.; Kato, Daiji; Morita, Shigeru; Murakami, Izumi; Yamamoto, Norimasa; Ohashi, Hayato; Yatsurugi, Junji; Nakamura, Nobuyuki

    2013-01-01

    We present spectra of highly charged tungsten ions in the extreme ultra-violet (EUV) by using electron beam ion traps. The electron energy dependence of spectra is investigated of electron energies from 490 to 1440 eV. Previously unreported lines are presented in the EUV range, and some of them are identified by comparing the wavelengths with theoretical calculations. (author)

  19. A facility for the analysis of the electronic structures of solids and their surfaces by synchrotron radiation photoelectron spectroscopy

    Science.gov (United States)

    Hoesch, M.; Kim, T. K.; Dudin, P.; Wang, H.; Scott, S.; Harris, P.; Patel, S.; Matthews, M.; Hawkins, D.; Alcock, S. G.; Richter, T.; Mudd, J. J.; Basham, M.; Pratt, L.; Leicester, P.; Longhi, E. C.; Tamai, A.; Baumberger, F.

    2017-01-01

    A synchrotron radiation beamline in the photon energy range of 18-240 eV and an electron spectroscopy end station have been constructed at the 3 GeV Diamond Light Source storage ring. The instrument features a variable polarisation undulator, a high resolution monochromator, a re-focussing system to form a beam spot of 50 × 50 μm2, and an end station for angle-resolved photoelectron spectroscopy (ARPES) including a 6-degrees-of-freedom cryogenic sample manipulator. The beamline design and its performance allow for a highly productive and precise use of the ARPES technique at an energy resolution of 10-15 meV for fast k-space mapping studies with a photon flux up to 2 ṡ 1013 ph/s and well below 3 meV for high resolution spectra.

  20. Electronic structure simulation of chromium aluminum oxynitride by discrete variational-X{alpha} method and X-ray photoelectron spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Youngmin; Chang, Hyunju; Lee, Jae Do [Korea Research Inst. of Chemical Technology, Taejon (Korea); Kim, Eunah; No, Kwangsoo [Korea Advanced Inst. of Science and Technology, Taejon (Korea)

    2002-09-01

    We use a first-principles discrete variational (DV)-X{alpha} method to investigate the electronic structure of chromium aluminum oxynitride. When nitrogen is substituted for oxygen in the Cr-Al-O system, the N2p level appears in the energy range between O2p and Cr3d levels. Consequently, the valence band of chromium aluminum oxynitride becomes broader and the band gap becomes smaller than that of chromium aluminum oxide, which is consistent with the photoelectron spectra for the valence band using X-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS). We expect that this valence band structure of chromium aluminum oxynitride will modify the transmittance slope which is a requirement for photomask application. (author)