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Optical properties of bulk Cd 1-x Mg x Se mixed crystals, grown from a CdSe, Mg, and Se melt by the Bridgman method, are presented. The alloys have a wurtzite type structure in the investigated range of composition, i.e. for 0=<x=<0.4. Measurements of the complex pseudo-dielectric function, < (ω)>=< 1 (ω)>+i 2 (ω)>, were performed at...
The adsorption of ultrathin films of Pt on W, Pt on Ir, and Pd on Mo field emitters has been studied with an emphasis on faceting processes, by means of field electron microscopy (FEM) under UHV conditions. The film thicknesses ranged from fractions of an atomic monolayer to several monolayers. From the analysis of field emission patterns and current-voltage measurements we have found that the steady-state...
Cd 1-x Mg x Se crystals for 0<x<0.55 have been grown by the high-pressure Bridgman method. Bulk chemical analysis of crystals was performed using an emission spectrometer. Auger electron spectroscopy (AES) with simultaneous argon ion sputtering has been used to monitor the changes of concentrations of particular elements in the sub-surface region of the samples. Comparison...
Epitaxial Fe 3 O 4 (001) thin films were grown on MgO(001) using molecular beam of 57 Fe at the oxygen partial pressure of about 1x10 -6 mbar. LEED patterns indicated perfect growth with a p(1x1) reconstructed surface (as labeled with respect to the bulk unit cell of magnetite) . In situ UHV conversion electron Mossbauer spectroscopy (CEMS) was applied to...
We study, both theoretically and experimentally, the existence and behavior of surface localized modes in a one-dimensional (1D) comblike photonic band gap structure. The structure is composed of a waveguide, along which dangling side branches are grafted periodically. We demonstrate a theoretical rule about the existence of surface states in such 1D periodic structures; namely, when one considers...
Scanning tunneling microscopy (STM) and atomic force microscopy (AFM) flow reactors working at pressure ~10 5 Pa were used to follow in situ the changes of the nanostructure of thin palladium film during the catalytic reaction of oxygen with hydrogen. STM images obtained in the course of the reciprocal oxygen-hydrogen titration arise as a superposition of charge distribution within the adsorbate...
Conversion electron Mossbauer spectroscopy (CEMS) was applied to model the buried interfaces in epitaxial 1-14 monolayer (ML) Fe(001) films sandwiched between Cr(001) layers. The local arrangement of Fe and Cr was derived by analysis of the experimental hyperfine field distributions determined from 80K CEMS spectra. A discontinuity in magnetic properties for the 6ML Fe film suggests that a modification...
We have evaporated Rh atoms onto polycrystalline aluminium substrate and studied the surface composition by Auger electron spectroscopy (AES). We have also explored the adsorption of CO molecules by thermal desorption spectroscopy (TDS). Both AES and TDS results exhibit dramatic changes during the sample heating and CO adsorption/desorption experiments. A Rh-Al alloy is probably formed on the surface...
The interaction between hydrogen and cobalt atoms leading in an external electric field to cobalt hydrides formation is studied both experimentally (with the use of time-of-flight atom-probe field ion microscope) and theoretically (ab initio quantum chemical calculations). It was found that in 15-20V/nm electric field stable molecules of CoH, CoH 2 and CoH 3 may be formed through the...
The results of the surface photovoltage (SPV) versus temperature measurements and surface photovoltage spectroscopy (SPS) for Cd 1-x Fe x Te surfaces for x=0.00, 0.02, 0 .05 and 0.07 are presented. From results of the SPS measurements the energy values of the four discrete energy levels have been determined and from the SPV measurements the densities of surface states above...
Field emission current noise of titanium adsorbed on the (111) tungsten crystal face was investigated. Measurements were carried out for coverages ranging from 0.2 to approximately 2 monolayers in the temperature range 300-1500K. A linear combination of two theoretical functions obtained by Gesley and Swanson for the diffusion model of current fluctuations was fitted to the experimental autocorrelation...
The elementary excitations (spin waves) in the system of two ferromagnetic films of different thicknesses exchange coupled through a nonmagnetic metallic spacer are investigated. The Hamiltonian of the system consists of the exchange, Zeeman and both the surface and interface anisotropy terms. The oscillatory exchange coupling between two ferromagnetic layers resulting from the interaction via itinerant...
In this work, the Auger electron spectroscopy (AES) was applied to study a monolayer of titanium nitride on a substrate of a TiNi alloy. It was found that the ratio of the repulsion energy U of two holes to the attractive energy V between atoms of nitrogen and titanium is constant and equals to U/V=18/17. The relationship between the degree of the surface coverage and the V/U parameter was stated...
The electronic-level structure and local density-of-states (LDOS) distributions are investigated for an infinite GaAs/Al x Ga 1-x As superlattice (SL) with two strongly spatially confined defect layers (the so-called δ-defects). The energy spectrum is determined by using a multi-matching procedure within the envelope-function approximation, while the LDOS is computed via...
The TiO 2 (110) surface, carefully characterized by STM, was used as a support for Au nano-clusters grown by thermal evaporation. The atomic bright rows imaged on the clean 1x1 TiO 2 (110) surface at the negative sample bias voltage are interpreted as bridging oxygen atoms. Gold was deposited at room temperature in doses corresponding to 0.013, 0.08 and 0.2 of the nominal Au(111) monolayer...
So far, as we considered the DLEED intensities within the theory based on the statistical approach, their temperature dependence was taken into account only via statistical distribution of adsorbate. The present approach includes the influence of temperature due to vibrations of elements at the substrate, which change the adsorption energy and the pair interaction potential, respectively. The above...
The atomic and electronic structures of Dy and Gd submonolayers adsorbed on the Mo(112) face have been investigated with the use of the LEED, EELS and AES techniques. The one-dimensional compression of the Dy films is accompanied by the appearance of a series of medium energy extra losses, whereas they are absent under analogous conditions for Gd. The effects indicate good correlation with the shape...
We present two methods of the Monte Carlo analysis of the chemical diffusion processes on solid surfaces. First method is based on the analysis of the decay of sinusoidal adsorbate density perturbations; the second one uses the Boltzmann-Matano procedure applied to the step-like density profile. The usefulness of both these methods is shown on extraction of the chemical diffusion coefficient from...
The interaction of O 2 with polycrystalline Co 50 Pd 50 alloy samples was studied by Auger electron spectroscopy (AES) and thermal desorption spectroscopy (TDS). The samples were oxidised in the temperature range of 300-773K with oxygen exposure up to 405L. AES studies revealed surface segregation of Co due to dissociative oxygen chemisorption on the CoPd surface...
Rigorous computer simulations of the dependence of the band-to-band photoluminescence quantum efficiency (Y PL ) were performed for n-type InP surfaces in a wide range of excitation light intensity, Φ (from 10 18 to 10 25 cm -2 s -1 ). A strong influence of the density of surface states (N SS ) and their capture cross sections...
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