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Photoemission spectra obtained during BaF 2 and CaF 2 deposition on a Si(100) surface are reported. The electronic structure of the interfaces is deduced from the experiments. The measured valence band offset for the BaF 2 /CaF 2 interface is equal to 0.5 eV.
The electronic properties of the UHV annealed iron phthalocyanine (FePc) thin films exposed to oxygen have been studied using Photoemission Yield Spectroscopy (PYS). Depending on the annealing temperature as well as the oxygen exposure, the variations of the work function were analyzed together with the effective density of the filled electronic states localized in the band gap below the Fermi...
Ultrathin chromium layers of increasing thickness were deposited on titanium substrates under UHV conditions. AFM was used to check the surface morphology and to optimize the evaporation parameters. In situ AES and APS measurements were performed on these samples. The APS overlayer and substrate signal intensities, as a function of the overlayer thickness, have been measured. Instead of the common...
The existence of localized and resonant optical waves associated with the surface of a semi-infinite superlattice or its interface with a substrate is reported considering the case of s-polarization (transverse electric modes). These modes appear as well defined peaks of the density of states, either inside the minigaps or inside the bulk bands of the superlattice. The density of states, function...
We present a new method of solving the self-consistent field equations in the coherent-potential approximation (CPA). In our approach, the coherent potential and the Green function of the effective medium are represented as continued fractions. It is shown that, contrary to the standard CPA method, it is possible to define an energy-independent Hamiltonian, which acts in an augmented space, so that...
The anisotropy of surface diffusion of lithium on the W(112) plane was investigated by means of the spectral analysis of the field emission flicker noise. The field emission microscope with a rotatable rectangular slit as a probe-hole was applied, which enabled to investigate surface diffusion along the chosen crystallographic direction. The spectral density function was measured for different angular...
Short-term temporal changes in the field electron emission characteristics were studied. The emission regime involves metal-insulator (M-I), metal-metal-insulator (M-M-I) and metal-insulator-metal-insulator (M-I-M-I) systems. In this paper, the data presented include the initial phenomenon of 'switch-on' currents, the capability of subsequent switching between two or more emission spectral modes,...
A standard LCAO semiempirical procedure is applied to a slab model of the Ge/RbF (100) system to calculate the dispersion relation E (k ) and the density of states. The electronic structure of the interface exhibits a surprising similarity to that of the ideal (unreconstructed) (100) surface of germanium.
The elastic stabilized jellium model is used for a description of the electrophysical properties of self-compressed metal particles in the semiclassical limit. From a condition of mechanical equilibrium, the exact analytical expressions for the first size corrections to the surface energy and electron chemical potential are derived. The obtained sum-rules are similar to those for the rigid stabilized...
Structure, work function and binding energy q of Dy and La layers adsorbed on tantalum single crystal Ta(112) plane (surface) were investigated using low-energy electron diffraction (LEED) and contact potential difference (CPD) techniques. A significant influence of temperature of the substrate on the work function dependences (n), where n is the adsorbate surface density, have been revealed...
NEXAFS has been applied to acetonitrile multilayer condensation and monolayer adsorption on Pt(111). The multilayer is partly oriented and characterized by a single π CN* resonance. NEXAFS confirms that acetonitrile adsorption on Pt(111) is strong. Particularly, the degeneracy of the π CN* resonances is lifted. The polarization dependence of the various resonances...
Optical transitions near the Fermi level in the (111) and (100) directions of tantalum were observed using the photofield emission method. The final and initial energies of the photoelectrons have been estimated based on the quantum energy and lowering of the top of the surface potential barrier at which shoulders in current-voltage characteristics appear. Electron energy values obtained for a few...
We performed angle-integrated inverse-photoemission experiments on the Au/GaP(110) interface in the low-coverage regime. For a gold deposition of 0.5 we found the IPES spectrum shifting by 0.25 eV towards lower energies below the Fermi reference level. This result is attributed to an excess of positive accumulated charge at the interface induced by the impinging electrons.This shift is consistent...
We present data on photoluminescence (PL) and the Franz-Keldish (FK) effect on ultra high vacuum cleaved CdTe(110) 1 1 surfaces by surface differential reflectivity (SDR). PL and FK effects on the clean surface have been studied as a function of an argon laser power with the sample at room temperature. PL spectra have been divided into two contributions: a free excitons peak, which determines the...
The carbon monoxide- and the oxygen-covered surfaces of [110]-oriented Pt tips and of [100] and [111]-oriented Rh tips were studied in the lithium field desorption microscope (Li FDM). The catalytic CO-oxidation reaction on Rh and Pt surfaces was studied in situ using Li + and O 2+ field ion modes of imaging. The influence of the modification of electron density near the surface,...
A new adsorption-desorption method for determining the efficiency of H 2 thermal dissociation on a hot metal surface is proposed. The results obtained by means of this method confirm the validity of Langmuir's equation describing H 2 atomization on a hot tungsten surface within the temperature range 1020-1315 K at a H 2 pressure of 2 10 -3 torr. A comparison...
The evaporation of bulk oxides of WO 2 and WO 3 and oxidised tungsten surfaces (metallic tungsten heated in an oxygen atmosphere) have been studied by the means of mass-spectrometry. The principal constituents of the vapour are found to be molecules of WO 2 , WO 3 W 2 O 6 and W 3 O 9 . These results differ from earlier reports, where...
The content of hydrogen and its depth profile in diamond like carbon (DLC) films deposited by the microwave plasma deposition technique is determined by Elastic Recoil Defection Analysis (ERDA) using 85 MeV i 58 Ni ions. Simultaneous detection of hydrogen and carbon recoils provided a method to determine the relative number of hydrogen:carbon atoms without using a standard H sample for...
Thin chalcogenide films from the Te 46-x As 32+x Ge 10 Si 12 (0 x 5) system have been prepared by thermal evaporation. The current-voltage characteristics in the temperature range 305-423 K and thickness range 116-364 nm is ohmic in the lower field regime followed by non-ohmic behaviour in the higher voltage regime which...
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