共查询到20条相似文献,搜索用时 15 毫秒
1.
J. Pyrlik 《Solid State Communications》1978,26(11):717-719
In electron energy loss measurements (50 keV) on monocrystalline silver films in transmission the intensity of the 3.8 eV volume plasma loss is found to be dependent on the crystal orientation. If the crystal is tilted relatively to the electron beam by an angle α the elastic intensity Iel in the primary direction oscillates by 10%, the intensity of the volume plasmon however varies much stronger similar to Iel; it can become even zero at certain angles α. The intensity of the surface loss is nearly proportional to the elastic intensity. An explanation of this phenomenon is missing. Presumably it must lie in the dynamic theory of electron diffraction. 相似文献
2.
Electron energy loss spectra are simulated for a C70 crystalline structure. It is found that the simulated spectrum is similar to the unoccupied density of states of a C70 molecule, indicating that the crystalline structure has only a small effect on the spectrum. Unlike the case of a single molecule, however, the main contribution to the second peak in the spectrum cannot be ascribed as being due to the equatorial atoms. 相似文献
3.
The complete set of optical fundamental functions is determined for diamond in the range from 4 to 32 eV. The features of the bulk and surface characteristic energy loss spectra are elucidated and the functions n eff(E) and ?eff(E) are calculated. The energies of volume and surface plasmons are established. 相似文献
4.
单晶光纤损耗谱测量装置 总被引:4,自引:1,他引:3
本文描述了一套用以测量单晶光纤损耗谱的装置。本装置由卤钨灯,单色仪,积分球,AgORbCs光电倍增管以及数据采集,处理和控制系统组成。可测量300~1150nm的光谱范围。利用本装置可获得单晶光纤的吸收光谱,透过率谱,散射光谱以及散射位置谱。 相似文献
5.
Experimental reflection electron energy loss (REEL) spectra are measured from aluminum for primary energies ranging from 130 eV to 2 keV. A Monte Carlo simulation is shortly described and used to calculate the same spectra. The focus is on reproducing the variable weight of surface and bulk losses as the surface sensitivity of spectra changes by changing the primary electron energy. The intensity of surface losses in the simulations is modulated by the thickness of the region where surface excitations occur. Simulations based either on a constant or an energy-dependent thickness for this layer are considered. In both cases, simulated spectra reproduce the experimental trend as a function of energy, though the correct surface-to-bulk intensity ratio for each energy is either underestimated or overestimated. 相似文献
6.
V.V. Nemoshkalenko V.G. Aleshin Yu.N. Kucherenko L.M. Sheludchenko 《Journal of Electron Spectroscopy and Related Phenomena》1975,6(2):145-150
Electron spectra of valence bands in copper, silver and palladium were calculated. It is shown that the probability of electron excitation from eg states exceeds that from t2g states. The density of electron states in the valence bands of these crystals differs markedly from the photoelectron energy distribution. 相似文献
7.
P.A. Thiry J. Ghijsen J.J. Pireaux R. Caudano 《Journal of Electron Spectroscopy and Related Phenomena》1983,29(1):193-198
From the beginning of the interaction of oxygen with the clean Mg(0001) and Mg(100) surfaces, two vibrational bands were measured by HREELS. The first one at 480 cm?1 is attributed to atomic oxygen adsorbed at the surface. The second band at 620 cm?1 is related to the stretching vibration of incorporated oxygen precursor to oxide formation. No specific difference was observed in the position and evolution of the two bands for both surfaces, but the electronic intensity reflected in the specular peak exhibited a totally different behaviour. The widths of the vibrational bands suggest a strong coupling with the continuum of electron-hole pairs of the metal. 相似文献
8.
9.
The Auger electron and characteristic loss spectra of plutonium have been obtained for the first time using a four grid retarding potential analyzer. The surface of this reactive metal was prepared by scribing in situ in good vacuum with a titanium carbide blade. Oxygen and carbon impurities were still present after scribing. The origin of the Auger electron and loss peaks is suggested, and a correlation is made with the peaks observed for uranium dioxide by Ellis and Campbell. 相似文献
10.
《Journal of Electron Spectroscopy and Related Phenomena》2002,122(3):231-237
A new approach is proposed for the analysis of reflection electron energy loss (REEL) spectra that were obtained for different electron-scattering configurations. A distinctive feature of the approach is that a REEL spectrum can be separated into two components that change in relative intensity with changes in the experimental configuration. No assumption is made about the number of peaks in the component spectrum and their shape. The suggested method is demonstrated on REEL spectra of aluminium, which is a traditional test object. It is established that in the range of energy losses 0–50 eV, the A1 REEL spectrum can be described by the sum of two components. The components of the spectra measured at different angles of primary electron incidence and exit angles for the detected electrons but with constant scattering angle have the same shape. The relative intensities of the two components define the spectral shape for different geometric conditions of the experiment. The shape of the components and their changes in relative intensity with change of primary electron energy give new information useful for development and further improvement of models used for studying medium energy (0.1–1.0 keV) electron scattering in the surface region of solids. 相似文献
11.
A. A. Klyukanov A. V. Catanoi 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,49(3):275-281
Microscopic many-body theory for electronic properties
of solid states is developed with an emphasis on the role of correlation
memory effects. Heisenberg equation of motion, fluctuation-dissipation
theorem and operators of commutation have been used to calculate
multiplasmon transmission electron energy loss spectra. Multiquantum
integral kinetic equation for the longitudinal complex dielectric function
is derived. Strong interaction between high-energy probe beam electrons penetrating the
solid state and plasma of valence electrons is taken into account. It is
shown that average number of high-frequency plasmons generated in every
collision process is more than one for typical values of metal parameters.
It is obtained that excitation of a good few plasmons is simultaneous event.
Calculated multiplasmon structure of electron energy loss spectra coincides
with experimental. 相似文献
12.
C.G. Olson J.H. Sexton D.W. Lynch A.J. Bevolo H.R. Shanks B.N. Harmon W.Y. Ching D.M. Wieliczka 《Solid State Communications》1985,56(1):35-37
The valence bands of epitaxial layers of A1N were studied by ultraviolet photoelectron spectroscopy and electron energy loss spectroscopy. A self-consistent band structure was calculated and the resultant density of states compared with the UPS spectra. Qualitative agreement was good, with discrepancies arising primarily from the neglect of dipole matrix elements. 相似文献
13.
N.R. Avery 《Surface science》1981,111(3):358-380
A dispersion analysis of the EELS from a W(001) surface in the range 1 < ΔE < 35 eV has been performed and compared with recent and complete optical data for tungsten. The non-dispersive (k ~ 0) EELS correlated well with a combination of the surface and bulk loss functions calculated from the optical data. Losses at 1–5 eV and a pair at 32 and 34.5 eV were assigned to interband and N6,7 core ionization excitations respectively. The principal bulk and surface plasmon losses were identified at 24.0 and 20.3 eV respectively. Two further losses at 14.0 and 9.6 eV were also observed and assigned to subsidiary plasmon losses. All four plasmon losses showed only minimal energy dispersion, never exceeding 1.5 eV. A momentum selectivity for separating bulk and surface interband losses was demonstrated with the non-dispersive losses arising from excitations within the bulk even with incident energies as low as 88 eV, whereas their dispersive counterparts were extremely sensitive to the chemical state of the surface. New adsorbate derived losses which develop during adsorption were associated with excitations from the new deep lying adsorbate levels to final state levels at or near the Fermi level. It was concluded that this final state was also responsible for the N6,7 ionization losses. 相似文献
14.
Rana N.S. Sodhi C.E. Brion 《Journal of Electron Spectroscopy and Related Phenomena》1985,36(2):187-201
Electron energy loss Spectroscopy has been used to obtain the inner shell excitation spectra of the methyl amines CH3NH2, (CH3)2NH and (CH3)3N for both the N 1s and C 1s regions. A spectrum of the N 1s region of NH3 is also presented at higher resolution than previously published data. The C ls spectra are all very similar and the discrete portions may be assigned to Rydberg transitions. However, features attributable to a σ* shape resonance are observed just above the N 1s and C ls ionization edges. The NH3 spectrum is ascribed to Rydberg transitions. The N 1s spectra of the methyl amines, however, become increasingly dominated by a σ* resonance in the continuum with increased methylation. The features in the inner-shell spectra are compared with the reported valence-shell optical absorption spectra and support the Rydberg assignment. The inner-shell spectra of (CH3)3N and NH3 are also compared with previously published inner shell electron energy loss spectra of NF3 and the third row phosphorus analogues PF3,P(CH3)3andPH3. 相似文献
15.
《Solid State Communications》1986,57(1):77-79
Reflection electron energy loss spectra of aluminium were studied for primary energies in the 500–2000 eV and loss energies in the 0–80 eV range. The absolute intensity observed could be well explained by using an electron-gas model for the inelastic electron scattering cross section and by assuming that the distribution of the path lengths travelled in the solid is exponentially decreasing. The attenuation length in this distribution is found to be on the order of the transport mean free path for elastic electron scattering. 相似文献
16.
The azimuthal dependence of electron energy loss spectroscopy (EELS) dipole and impact scattering intensity has been measured. Spectra for a saturation coverage of H adsorbed on W(110) exhibit loss peaks due to impact scattering from adsorbate vibrational modes. The intensity of the 160 meV loss peak has been measured as a function of the azimuthal angle between the scattering plane and a mirror plane of the urface. The angular pattern has strong maxima oriented perpendicular to the <111 > rows of atoms on the surface, and has the C2v symmetry of the W(110) surface. This azimuthal dependence is strikingly different from the nearly isotropic angular dependence of dipole scattering from Cl adsorbed on W(110). Selection rules for impact scattering account for the general features of the angular pattern based on asymmetric stretch modes associated with bridge site H atoms.We have shown that the azimuthal dependence of the 36 meV Cl/W(110) dipole scattering loss peak is isotropic and that the 160 meV H/W(110) impact scattering loss peak exhibits a striking azimuthal pattern with C2v symmetry. The symmetry and deep minima suggest that selection rules play a central role in determining the azimuthal pattern. Application of these rules to two orthogonal directions (as in ref. 6) may be misleading, as is clear from Fig. 2, because essential features of the pattern will not be observed. Our analysis of the full pattern has suggested two bridge sites may be occupied at saturation coverage, but has still not resolved certain questions about the H/W(110) system.
SITE | LONG BRIDGE | SHORT BRIDGE | DISTORTED BRIDGE | |||
MIRROR PLANES | [001], [10] | NONE | [10] | |||
2-FOLD ABOUT Z | YES | YES | NO | |||
PARALLEL MODES | [001] | [10] | [11] | [12] | [001] | [10] |
DIRECTIONS OF ZERO SCATTERING | [001] * [10] | [001] * [10] | [11] [12] | [11] [12] | [001] * [10] | NA |