Characteristic electron loss spectra and electronic structure of thallium chloride

The bands, state densities N(E), and permittivity are theoretically found for TlCl crystals. On the basis of the experimental characteristic electron loss spectra, the spectra of the complete set of optical functions including permittivity and bulk electron loss spectra are calculated and decomposed into components. The obtained data are compared with the well-known theoretical results. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 8–11, June, 2008.     

Characteristic electron energy losses in germanium

The characteristic electron energy loss spectrum of germanium was studied in a transmission type experiment as a function of the changes in structure due to electron bombardment. The structure of the material was characterized by electron micrograph and diffraction techniques. The electron energy loss spectrum of germanium was studied up to 45 eV, and loss peaks were observed at 15.7 eV and 31.6 eV as well as a 6 eV carbon loss. The positions of the most intense characteristic energy loss peak at 15.7 eV and its first multiple were constant for a large variation in the lattice parameters for the individual films.     

Characteristic energy losses of 8 keV electrons in liquid In-Al and In-Bi alloys

Measurements have been made of the characteristic energy losses of 8 kev electrons in a series of liquid In-Al and In-Bi alloys in order to avoid the confusing effects of phase mixtures present in most similar studies of solid alloy systems. Loss spectra were measured in a reflection-type scattering geometry with total electron scattering angles of 15° and 70°. Two principal energy loss peaks, identified as being due to surface plasmon and to volume plasmon excitation, were found to vary as a function of alloy composition in each system. Deviations from the variation expected from a simple free-electron model could be interpreted in some cases in terms of an interband electronic transition occurring near the measured volume and surface energy-loss peaks. For bismuth-rich In-Bi alloys and for indiumrich In-Al alloys the transmission energy and oscillator strength could be estimated and shown as a function of composition.     

Plasma losses of electron energy and secondary electrons of discrete energies in aluminum

Discrete energy' loss is examined for electrons of energy 30–116 V. The losses due to excitation of three types of plasma wave are found; these plasmons have energies of 15.5, 9.5, and 7 eV. The energy distribution curves for the secondary electrons contain groups with discrete energies, which in aluminum coincide with the plasma energies, and so arise by decomposition of plasmons.     

Energy losses of electrons in oriented crystals

Abstract

Within the framework of the multistring model of axial channeling of electrons the method for calculating the losses to radiation in channeling is proposed. The physical model includes the multiple scattering, the beam and target characteristics. The simulated results are compared with the experimental data.     

Raman spectroscopy of thallium chloride in the melting region

We have followed the temperature dependence of the second order Raman spectra of b.c.c. thalliumchloride crystals and polycrystalline powders with particular regard to the region immediately preceding and following melting. Our results, concerning mainly the behavior of the LA(X)-TA(X) peak, imply the appearance of a new damping mechanism for the TA(X) phonon approximately 10°C below the melting temperature. Furthermore, this conjecture seems to be supported by calorimetric measurements near melting.     

Energy losses of fast electrons in multi-layer systems

Starting from Maxwell's equations a formula for the energy loss probability of fast electrons in systems of a given number of thin layers is derived for normal incidence. Retardation effects are neglected. For three layers of arbitrary thickness the equations are fully solved. As examples, a two-metallic-layer system with energy-dependent dielectric functions is discussed. Furthermore, the tarnish of metals e.g. Al–Al₂O₃, Be–BeO, Ag–Ag₂S is considered as three-layer systems. The energy loss spectrum of the system Al₂O₃–Al–Al₂O₃ is calculated in agreement with the experiment. It turns out that the bulk longitudinal optical mode of the covering layer is excited in the infra-red. In the case of the oxidation of a dielectric film the transversal mode of the oxide is expected to prevail in the energy loss spectrum.     

Characteristic energy losses on carbon contaminated layers correlated with secondary electron,auger electron emission and contrasts in scanning microscope

The secondary electron (SE) spectrum (0 < E < 50 eV) has been analysed by means of a CMA. Samples were clean aluminum, aluminum becoming carbon contaminated, sintered graphite powder, electro chemically deposited polymer on platinum and monocrystals of silicon carbon contaminated. When the clean Al surface is becoming carbon contaminated a quick decrease of surface plasmon and bulk plasmon losses is observed whereas a main characteristic energy loss peak (ELS) at 20 eV and a secondary electron peak at 20 eV appear simultaneously. Both peaks are very sensitive general features of carbon contaminated surfaces. The main loss peak is attributed to the excitation of the carbon-carbon bounds (σ → σ¹) as already proposed in the transmission ELS. The few eV change of the loss peak energy of various carbon compounds may correspond to slightly different carbon-carbon distances. The 20 eV secondary electrons could be produced by the relaxation of the excited state (σ¹ → σ transition) via an Auger process. The cross section for molecular electronic excitation is higher than that of atomic ionization for inner level. The loss peak is as intense as the SE peak and higher by more than two orders of magnitude than the C KLL Auger peak. The modification of secondary emission under carbon contamination has been observed on a silicon sample by Scanning Electron Microscopy (SEM) in the Secondary Electron Image (SEI) mode.     

Synchrotron reflectivity spectrum, characteristic electron losses, and electronic structure of TlCl crystals

Spectra of two complete sets of TlCl fundamental optical functions are obtained in the energy range 0–25 eV using experimental reflectivity and characteristic electron loss spectra. The ?₂ and-Im?^?1 spectra are decomposed into components, and their main features are determined. The bands, ?₂, and the localization of transitions in the Brillouin zone are calculated. The experimental and theoretical transitions are compared with theoretical data on the electronic structure of a TlCl crystal.     

Characteristic electron energy loss structure for clean and oxidized chromium surfaces

AES and EELS spectra have been measured on clean and oxidized chromium surfaces. Auger peaks at 31.0 and 44.0 eV of the oxide are attributed to cross transitions between chromium and oxygen: {M_2,3(Cr)V(Cr)V(O)} and {M₁(Cr)L₁(O)V(Cr)} respectively. Core loss features are consistent with valence band structure with a newly observed loss peak at 41.1 eV for the oxidized surface being ascribed to a core exciton with binding energy E_b = 1.6 eV.     

Energy losses and scattering of fast electrons in a dense plasma

This paper describes an algorithm for the calculation of specific energy losses and multiple scattering of fast electrons in a plasma, taking into account the interaction of the electrons of the beam with the bound and free plasma electrons and with the plasma. Results are presented of calculations for aluminum and lead plasmas with density 0.001-1 of normal and with temperature up to 1 keV for initial electron kinetic energy of 1 MeV. The energy-loss distribution in an aluminum plasma is calculated by the Monte-Carlo method.Tomsk Polytechnic University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 112–116, September, 1993.     

Characteristic structure in core electron spectra of metals due to the electron-plasmon coupling

The coupling of metallic core electrons to the density fluctuations of the conduction electrons is studied. Due to the strong electron-plasmon coupling there is a characteristic satellite structure in the core electron spectrum, starting at the plasma energy?ω _p below the quasiparticle level and with a maximal spectral weight at (1.6–2.5)×?ω _p below the same level. The total spectral weight in the satellite band is 50–100 percent of the quasiparticle weight, the actual value dependent on the density of the conduction electrons. The possible implications on X-ray photoemission, soft X-ray emission and absorption, and inelastic scattering of electrons are drawn. Particularly, a close correspondence with the location of the fine structure of the L_2,3 absorption spectrum of Al is found. The relation to the cohesive energy is also considered.     

Electric conductivity and the change of structure of thallium chromate

It is reasonable to expect that the well known analogy between the compounds of monovalent thallium and silver will also apply to the properties of the chromates of these substances. The results of our measurements of the thermoelectric voltage and the temperature dependence of electric conductivity of silver chromate, presented in [1] and [2], confirmed the semi-conductive character and indicated a change in the structure of this substance at 489°C.This paper gives the results of measurements of the conductivity of thallium chromate over the temperature range of 200 to 600°C, of the effect of oxygen on conductivity, and of the sign of thermoelectric voltage; further, for purposes of comparison, data obtained in the differential thermal analysis and in reflection spectrum studies. The analogy with silver chromate revealed by these measurements is surprisingly strong and holds equally well for the temperature dependence of electric conductivity as for the sign of thermoelectric voltage, and even for the change in the structure.     

Ionization of K-shell electrons by electron impact

We have investigated the universal scaling behavior for cross sections of the single K-shell ionization by electron impact. The calculations are performed within the framework of non-relativistic perturbation theory, taking into account the one-photon exchange diagrams. Special emphasis is laid on the near-threshold energy domain. The results obtained are applicable for wide family of atomic targets with moderate values of the nuclear charge Z.     

Path distribution of emission electrons with small energy losses in solids

An algorithm for the calculation of both the electron elastic reflectivity and the electron path distribution in a substance is proposed. In the approximation of quasi-elastic electron scattering the energy-loss spectra in the vicinity of the elastic reflection peak, as well as near the Auger and photoelectron lines are considered. For the geometry of a cylindrical mirror analyzer the differential coefficients of 2 keV electrons elastically reflected from the surfaces of 26 elementary substances (4 Z 82) have been studied. The numerical calculations and the experimental data are compared. Formulae useful for processing emission spectra are derived.     

Total energy losses of relativistic electrons passing through a polymer composite

The total energy losses of electrons having different energies and passing through a polymer composite based on high-impact polystyrene and organic-siloxane filler made of methylpolysiloxane xerogel are calculated. The transmission coefficients of electrons and their mean free paths in the composite are simulated. It is found that the composite exhibits a high radiation resistance to corpuscular (electron) emissions.