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1.
D’Addato et al. [S. D’Addato, P. Luches, R. Gotter, L. Floreano, D. Cvetko, A. Morgante, A. Newton, D. Martin, P. Unsworth, P. Weightman, Surf. Rev. Lett. 9 (2002) 709] studied the variation with Fe coverages in the relative Fe L3-M4,5M4,5 Auger electron spectroscopy (AES) spectral satellite intensity of ultrathin Fe films grown on Cu(1 0 0) by sweeping photon excitation energy through the Fe L2-level ionization threshold. They interpreted that the M4,5 hole in the L3M4,5 double-hole state created by the L2-L3M4,5 Coster–Kronig (CK) decay remains localized for longer than the L3-hole lifetime for the 0.3 and 10 ML coverages but has a lifetime comparable to the L3-hole lifetime for the 1 ML coverages. The present many-body theory shows that when the M4,5 hole created either by the CK decay or by the L3M4,5 shakeoff hops away from the ionized atomic site and becomes completely screened out prior to the L3-hole decay, the Fe L2-L3M4,5-L3-M4,5M4,5 AES main line as well as the Fe L3 M4,5 (satellite)-L3-M4,5M4,5 one, both of which are identical in line shape to the Fe L3-M4,5M4,5 one, dominate in the Fe CK preceded AES spectrum. The present analysis shows that the delocalization time of the M4,5 hole created in the 1 ML Fe/Cu(1 0 0) system by the L2-L3M4,5 CK decay is much shorter than the L3-hole lifetime so that the Fe L3-M4,5M4,5 AES spectral line shape hardly changes, except for the presence of a very weak spectator L2-L3M4,5-M4,5M4,5M4,5 AES satellite, when the photon excitation energy is swept through the Fe L2-level ionization threshold. For the 0.3 ML coverages the M4,5-hole delocalization time is still shorter than the L3-hole lifetime. 相似文献
2.
The coincidence L3 and M3 photoelectron spectroscopy (PES) main lines of Cu metal are calculated by a many-body theory. There is no peak-energy shift between the singles PES main line and the coincidence one. The asymmetric narrowing of the coincidence PES main line on the low kinetic energy (KE) side is very small. This is in accord with recent experimental findings. In Cu metal, the shakeup satellite intensity is small and the main-line satellite separation energy is much larger than the core–hole lifetime width. The interference via the final-state interaction is negligible. In the PES main line, the imaginary part of the self-energy by shakeup excitations, which is very small compared to the core–hole lifetime width, decreases very slowly in linear with photoelectron KE. The branching ratio of Auger decay of a single hole state then increases very slowly in linear with photoelectron KE so that the deviation of the coincidence PES main line from the singles one is very small. The 939 eV structure seen only in the coincidence L3 PES spectrum of Cu metal is attributed to the enhancement of the inelastic peak of a smaller energy loss due to electrons of a smaller average emission depth measured in coincidence with the elastic Auger peak. The structure will not be enhanced in the singles PES spectrum. The background subtraction in the coincidence spectrum cannot be the same as that in the singles one. Such consideration is necessary before we can conclude about the asymmetric narrowing on the low KE side. A unique capability of APECS by which one can determine the photoelectron KE dependent part of the imaginary part of the self-energy is pointed out. 相似文献
3.
The L2,3-M2,3V resonant Auger electron spectroscopy (RAES) spectrum of Ti metal measured by Le Fêvre et al. [P. Le Fêvre, J. Danger, H. Magnan, D. Chandesris, J. Jupille, S. Bourgeois, M.-A. Arrio, R. Gotter, A. Verdini, A. Morgante, Phys. Rev. B69 (2004) 155421] is analyzed in the light of relaxation and decay of the resonantly excited L2,3-hole states. The relaxation time of the resonantly excited L2,3-hole state to the fully relaxed (screened) one is much shorter than the L2,3-hole Auger decay time, whereas the participant Coster–Kronig (CK) decay time of the resonantly excited L2-hole state to the fully relaxed L3-hole state at the L2 resonance is as short as the relaxation time of the resonantly excited L2-hole state to the fully relaxed one. The excited electron is predominantly either rapidly decoupled from the L2,3-hole decay or annihilated by the participant CK decay. Thus, near the L2,3 edges the L2,3-M2,3V RAES spectral peak appears at constant kinetic energy. The L2,3-M2,3V RAES spectrum shows a normal L2,3-M2,3V Auger decay profile not modulated by the density of empty d states probed by the resonant excitation. Not only the relaxation time but also the participant CK decay time depends on photon energy because they depend on the density of empty d states probed by the resonant excitation. As a result, the L2,3 X-ray absorption spectroscopy spectral line broadening depends on photon energy. 相似文献
4.
The coincidence N23-VV Auger-electron spectroscopy (AES) spectra and N23 photoelectron spectroscopy (PES) spectra of Ag metal are analyzed. Here NX is the notation for atomic shell Nx (X = 2, 3). The band-like feature in the coincidence N23-VV AES spectra is much more intense than that in the coincidence M45-VV ones because the potential in the delocalized two-hole state is less attractive than that in the localized one. The partial N23-VV super Coster–Kronig (sCK) transition rate depends critically on both the final-state potential and the sCK-electron kinetic energy (KE) because the KE is low, whereas the partial M45-VV Auger-transition rate is fairly independent of them because the KE is very high. As a result, the partial sCK-transition rate to the band-like state is enhanced compared to that to the atomic-like localized state. The low KE tail in the coincidence N23-VV AES spectra which is likely due to the sCK transition involving more than two electrons, is more enhanced than that in the coincidence M45-VV ones. This is due to the enhancement of the partial sCK-transition rate by the presence of extra holes in the final state. The sharp peaks of small intensity on the lower KE side of the main line in the coincidence N2 PES spectrum are tentatively attributed to the shakeup satellites. 相似文献
5.
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. 相似文献
6.
The valence hole created in Ni metal either by the L2-L3V Coster–Kronig (CK) transition or by the L3V shakeup/off becomes screened out prior to the L3-hole decay. We denote the atomic shell Lx (x = 2, 3) by LX. The metastable two-hole L3V state relaxes to the fully relaxed single L3-hole state before the L3-hole decays. Thus, the coincidence L2-L3(V)-VV(V) Auger-electron spectrum resembles closely the coincidence L3-VV Auger-electron spectrum. The final state of the CK transition preceded Auger transition is a two-hole state rather than a three-hole state. The four-hole satellite about 8 eV below the L3-VV main line in the singles (non-coincidence) Auger-electron spectrum is partly due to the L3VV-VVVV transition and the L2-L3VV-VVVV transition. The valence holes created either by the L2-L3VV transition or by the L3VV double shakeup/off remain localized during the L3-hole decay. The L3-hole lifetime widths of Fe, Co and Ni metals are determined from the APECS spectra. The agreement between experiment and theory (the independent-particle approximation) is poor. 相似文献
7.
Masahide Ohno 《Journal of Electron Spectroscopy and Related Phenomena》2007,160(1-3):15-21
The quasi-particle approximation for the 4p4d state of the metallic elements around Cd breaks down because of very rapid 4p4d–4d3 super Coster–Kroning (sCK) decay of the 4p hole in the presence of the spectator 4d hole. Here the underbar is a hole. As a result, the 4p4d multiplet coupling breaks down. We can examine the presence or absence of the 4p4d multiplet by Auger-electron sCK-electron coincidence spectroscopy measurement of the 3d–4p4d–4d3 Auger-preceded sCK transitions. We collect the sCK-electrons in coincidence with the Auger-electrons of a selected kinetic energy (KE) and vice versa. If the multiplet coupling breaks down and does not exist, the coincidence sCK-electron (or Auger-electron) lines shift as much as the Auger-electron (or sCK-electron) analyzer's selected KE is varied. We can determine not only the three 4d-hole sCK final-state energy but also the presence or absence of the 4p4d multiplet by Auger-electron sCK-electron coincidence spectroscopy. The unique capability of the coincidence measurement by which one can determine the correlation between an Auger-electron and a sCK electron generated, respectively, by creation and annihilation of the same Auger two-hole final state is very useful, even when the quasi-particle approximation of the two-hole state breaks down. 相似文献
8.
Spin polarization of L23M23M23 Auger electrons from ferromagnetic Fe83B17 is calculated with a simplified model, and compared with recent experiments. The Auger electron spectrum has two peaks, corresponding to the singlet and triplet final states of a 3p hole pair. It is shown that the spin polarizations of the singlet and triplet peaks, respectively, originate from the exchange interaction between 3d and 2p spins and that between 3d and 3p spins. Similar effects are expected to be observed commonly for L23M23M23 Auger electrons from various ferromagnetic materials including transition elements. 相似文献
9.
The Al Kα excited M4,5N4,5N4,5 Auger spectrum of Ba has been measured from the metallic sample evaporated on a Ag substrate. The spectrum has been decomposed into individual line components after the background subtraction. The decomposed spectrum has been compared with the theoretical spectrum calculated for the 4d?2 final state configuration in the mixed coupling scheme applying jj-coupling for the initial state and intermediate coupling for the final state. The most prominent structure of the spectrum shows the two 4d-hole coupling, but the structure which is caused by the Auger transitions M,45N2,3V has also been observed. The screening of the core holes in Ba metal seems to be produced by (5d6s) electrons. The simple excited atom model HF-calculations give an Auger kinetic energy shift (metal-free atom) of 16.7 eV, which is comparable to the experimental value 14–18 eV. 相似文献
10.
Charge-transfer hole-lifetime broadening of the Cu Auger-electron spectra of high Tc superconductors
《Journal of Electron Spectroscopy and Related Phenomena》2005,148(3):129-136
The satellite intensity in the Cu L23-VV Auger-electron spectrum of the high Tc superconductor (YBa2Cu3O7−x, 123) is much more enhanced as compared to that of CuO. This enhancement was previously interpreted by Ramaker et al. [D.E. Ramaker, N.H., Turner, F.L. Hutson, Phys. Rev. B 38 (1988) 11368] as a result of the mixing between the ddp and dpp states. Here, d is a hole in the Cu 3d band and p is a hole in the O 2p band. However, the dramatic Auger electron spectroscopy (AES) spectral lineshape change from CuO to 123 is not only in the charge-transfer (CT) satellite but also in the main-line width. The change arises from the transit of the “pairing” of two bound d holes in the ddp state to that of two bound p holes in the dpp state. As a result, in CuO there is no CT satellite but the dd state becomes a resonant state broadened by the CT hole-lifetime broadening, whereas in 123 the dd state becomes a mixture of a resonant-like state and nonresonant band states. The present many-body theory can explain the overall AES lineshape change from CuO to 123. 相似文献
11.
Masahide Ohno 《Journal of Electron Spectroscopy and Related Phenomena》2008,162(3):134-145
The relative spectral intensity of the band-like two M4,5-hole state to the atomic-like localized one is much suppressed in the coincidence M3–M4,5M4,5 super Coster–Kronig (sCK) electron spectrum of Cu metal compared to the one in the coincidence L3–M4,5M4,5 Auger electron spectroscopy (AES) spectrum. The M3-hole lifetime width of Cu metal is calculated by an ab initio atomic many-body theory (the extended relaxed core random phase approximation with exchange). The calculated M3-hole lifetime width of Cu metal agrees well with the experimental one. The M3–M4,5M4,5 sCK decay width of Cu metal decreases much with delocalization of the two M4,5 holes in the sCK final state, whereas the Auger decay width is fairly independent of localization and delocalization of the two M4,5 holes in the Auger final state. Thus, the relative spectral intensity of the band-like state is much suppressed in the coincidence M3–M4,5M4,5 sCK-electron spectrum of Cu metal compared to the one in the coincidence L3–M4,5M4,5 AES spectrum. 相似文献
12.
Experimental L3-M4,5M4,5 Auger spectra of metallic Cu and Zn show distinct characteristics of free-atom spectra but do not reflect the band structure. This quasi-atomic phenomenon in solids is tentatively explained as electron localization due to increased screening. 相似文献
13.
Surface composition and depth profile of native oxide on Fe67Co18B14Si1 metallic glass has been investigated using Auger electron spectroscopy. The native oxide is compared with chemisorbed oxygen on the cleaned surface. Results indicate that boron segregates on the surface in the presence of oxygen. The low energy L23M45M45 peak of iron in metallic glass is compared with that in crystallized sample and pure iron foil. 相似文献
14.
L. Pidol O. Guillot-Noël B. Viana D. Gourier 《Journal of Physics and Chemistry of Solids》2006,67(4):643-650
Two Ce3+-doped scintillator crystals, LSO (Lu2SiO5:Ce) and LPS (Lu2Si2O7:Ce), are studied by EPR spectroscopy. The analysis indicates that Ce3+ substitutes for Lu3+ ion in a C2-symmetry site for LPS and in two C1-symmetry sites for LSO, with a preference for the largest one, with 6+1 oxygen neighbors. Angular dependence of the EPR spectrum shows that the electronic ground state of Ce3+ is different in these two matrices. It is mainly composed of |MJ|=5/2 state in LPS and |MJ|=3/2 state in LSO. The temperature dependence of the linewidth shows a noticeably long spin lattice relaxation time, especially in LPS, which is the result of a stronger crystal field in LPS than in LSO. 相似文献
15.
Klaus Schwidtal 《Surface science》1978,77(3):523-536
A theoretical model is proposed on how a Si dangling bond associated with an oxygen vacancy on a SiO2 surface (Es′ center) should be observed by Auger electron spectroscopy (AES). The Auger electron distribution NA(E) for the L23VV transition band is calculated for a stoichiometric SiO2 surface, and for a SiOx surface containing Si-(e?O3) coordinations. The latter is characterized by an additional L23VD transition band, where D is the energy level of the unpaired electron e?. The theoretical NA(E) spectra are compared with experimental N(E) spectra for a pristine, and for an electron radiation damaged quartz surface. Agreement with the theoretical model is obtained if D is assumed to lie ≈2 eV below the conduction band edge. This result shows that AES is uniquely useful in revealing the absolute energy level of localized, occupied surface defect states. As the L23VD transition band (main peak at 86 eV) cannot unambiguously be distinguished from a SiSi4 coordination L23VV spectrum (main peak at 88 eV), supporting evidence is presented as to why we exclude a SiSi4 coordination for our particular experimental example. Application of the Si-(e?O3) model to the interpretation of SiO2Si interface Auger spectra is also discussed. 相似文献
16.
Lata AgrawalAlo Dutta Shantiranjan ShannigrahiB.P. Singh T.P. Sinha 《Physica B: Condensed Matter》2011,406(5):1081-1087
The complex perovskite oxide In(Mg1/2Ti1/2)O3 (IMT) is synthesized by a solid state reaction technique. The X-ray diffraction of the sample at 30 °C shows a monoclinic phase. The dielectric properties of the sample are investigated in the temperature range from 143 to 373 K and in the frequency range from 580 Hz to 1 MHz using impedance spectroscopy. An analysis of the dielectric constant ε′ and loss tangent (tan δ) with frequency is performed assuming a distribution of relaxation times. The Cole-Cole model is used to explain the relaxation mechanism in IMT. The scaling behavior of imaginary part of electric modulus (M″) shows that the relaxation describes the same mechanism at various temperatures. The electronic structure and hence the ground state properties of IMT is studied by X-ray photoemission spectroscopy (XPS). The valence band XPS spectrum is compared with the electronic structure calculation. The electronic structure calculation indicates that the In-5s orbital introduces a significant density of states at the Fermi level, which is responsible for a high value of conductivity in IMT. 相似文献
17.
On the Auger-photoelectron coincidence spectroscopy spectra of Cu(100), Cu metal and CuOx/Cu surface
《Journal of Electron Spectroscopy and Related Phenomena》2002,124(1):39-51
The M3–VV Auger-photoelectron coincidence spectroscopy (APECS) spectrum of Cu(100) and the L3–VV APECS spectra of Cu metal and CuOx/Cu surface are analyzed in detail. The narrowing and energy shift of the photoelectron line in the M3–VV APECS spectrum is well predicted by the present theory. The spectrum shows the presence of the M2–M3(V)–VV(V) decay in which a hole in the 4s band hops away prior to the decay of M3 hole. The analysis of the L3 photoelectron spectra of Cu metal measured in coincidence with the 3F or 1G Auger line raises a question concerning the presence of two different core–hole states upon the L3 level ionization recently proposed by Thurgate and Jiang [Surf. Sci. 466 (2000) L807]. The analysis of the L3–VV APECS spectrum of CuOx/Cu shows that the final-state charge–transfer interaction plays an important role in CuO. 相似文献
18.
《Journal of Electron Spectroscopy and Related Phenomena》1999,98(2-3):129-133
Titanium nitride thin films were deposited on monocrystalline silicon (mc-Si) substrates by direct current reactive magnetron sputtering. Auger electron spectra (AES) of deposited films at different nitrogen partial pressures, show the typical N KL23L23 and Ti L3M23M23 Auger transition overlapping. Also, changes in the Ti L3M23M45 Auger transition peak are observed. X-ray diffraction and high resolution electron microscopy (HRTEM) of a golden color TiN/mc-Si sample, reveal a preferential polycrystalline columnar growth in the 〈111〉 orientation. This sample was also analyzed by electron energy-loss spectroscopy (EELS). The N/Ti elemental ratio is slightly different to the value determined by AES. Atomic distribution around the N atoms is in agreement with that expected from the N atom in the fcc unit cell of TiN. This distribution was obtained via an extended energy-loss fine structure (EXELFS) analysis from EELS spectra. 相似文献
19.
When the shakeup/down excitations are not negligible in the core-level electron ionization, the photoelectron spectral peak measured in coincidence with a selected singles (noncoincidence) Auger-electron spectral peak does not necessarily coincide with the singles one. We discuss how the interference between the core-hole decay of a fully relaxed core-hole state and that of an incompletely relaxed one via the interaction between the final states created by the respective core-hole decays, affects the kinetic energy shift and asymmetrical lineshape change of the coincidence photoelectron spectrum compared to the singles one. When the final-state interaction is considerable, the interference reduces much the energy shift and the asymmetrical lineshape change. By the Auger-photoelectron coincidence spectroscopy (APECS) we can study the interference effect which does not manifest in the singles photoelectron spectrum. We discuss also the interference effect when the core-hole decay rates of both the fully relaxed core-hole state and the incompletely relaxed one depend critically on the changes in both the Auger-electron kinetic energy and the final-state potential. The effect is fairly independent of the changes. 相似文献
20.
A series of samples ZnxFe3−xO4 have been prepared by the chemical coprecipitation technique and characterized by X-ray diffraction (XRD), vibrating sample magnetometry (VSM) and X-ray photoelectron spectroscopy (XPS). XRD demonstrates all the samples of ZnxFe3−xO4 have a spinel structure same as Fe3O4. The magnetic hysteresis loops of ZnxFe3−xO4 obtained from VSM indicate that the saturation magnetization has a maximum when x is ∼1/3. The chemical states of Fe atoms and Zn atoms in zinc ferrites have been measured using XPS and Auger electron spectroscopy (AES). The Fe 2p core-level XPS spectra and Zn L3M45M45 Auger peaks have been analyzed and the results have been discussed in correlation with the samples’ magnetic properties. These results suggest most of Zn atoms occupy the tetrahedral sites and a small amount of them occupy the octahedral sites. 相似文献