A. A. Khaidarov

Formation of aluminum island films under electron irradiation of a sapphire surface

The present paper is devoted to experimental investigation of electron-stimulated desorption from a single-crystal sapphire surface. Using Auger electron spectroscopy metallization of the sapphire surface, the character of which is dependent on the electron beam parameters, is observed under low-energy electron bombardment,. Using atomic-force microscopy, images of metal island films with a diameter of 50–100 nm are obtained.

Desorption of atomic particles and surface modification of fluorides under electron irradiation

Low-energy electron stimulated desorption (ESD) and surface modifications of CaF2 and BaF2 single crystals were experimentally studied at different surface temperatures. A technique based on the dependence of the surface composition on the electron irradiation dose was applied to determining the ESD cross section. The surface composition was measured by Auger electron spectroscopy (AES). Surface topography was examined by atomic force microscopy (AFM). The ESD mechanisms for fluorides were discussed.

Changes in the Composition and Surface Structure of Alloys in Regions with Varying Deformation

The change in the structure and composition of deformed regions hidden beneath the surface of samples are studied experimentally upon their identification by the method of successive processes of polishing and sputtering. Two present-day steel coins coated with different binary alloys, a 1-ruble coin (coated with the alloy Ni1%Fe) and a 50-kopeck coin (coated with the tompak alloy Cu10%Zn), and also a 5-kopeck coin minted in 1990 consisting of brass L60 are used as the samples. It is found that a change in the surface structure (different for the studied coins) and an increase in the light-component concentration take place in the region of increased deformation by pressing due to its diffusion to the side of greater deformation. The obtained results can be used for improving the means of determining hidden deformed regions using sputtering and stage-like analysis of the surface composition.

Anisotropy of secondary ion emission from a Ni4Mo single crystal

The azimuthal and polar angle distribution of Ni+ and Mo+ ions emitted from an ordered Ni4 Mo single crystal irradiated with 10-keV Ar+ ions was studied. Different azimuthal distributions for Ni+ and Mo+ ions emitted from the (001) Ni4Mo face were detected; emission maxima were observed in 〈 011 〉 and 〈 001 〉 directions for Ni+ and Mo+ ions, respectively. It was shown that polar distributions of nickel’s secondary ions vary with its energy. The observed systematic features were explained by correlated collisions in the upper layers of a Ni4Mo single crystal.

Electron-beam charging of dielectrics preirradiated with moderate-energy ions and electrons

The effects of charging of dielectric targets irradiated with moderate-energy electrons in a scanning electron microscope are examined. Considerable differences in the kinetics of charging of the reference samples and the samples preirradiated with ions and electrons are reported. These differences are attributed to the processes of radiation-induced defect formation in Al2O3 (sapphire) and SiO2 that are, however, dissimilar in nature. The contributions of surface structure modification and changes in the electrophysical parameters of the surface (specifically, the charge spreading effect) are revealed. Critical doses of irradiation with Ar+ ions and electrons inducing active defect formation in dielectric targets and critical values of internal charge fields producing a significant contribution to the temporal parameters of Al2O3 and SiO2 charging are determined.

New possibilities and some artifacts of the cathodoluminescent mode in scanning electron microscopy

Lightning inside the chamber of a scanning electron microscope (SEM), caused by electrons being scattering from a sample (and parts of the chamber), is observed and analyzed. These electrons generate the luminescence in a Thornly–Everhart collector. This parasitic effect (artifact) must be considered and eliminated in all experiments with the cathodoluminescent (CL) mode of SEM. A new technique for measuring surface potential on dielectric samples is proposed. It is based on variations in the CL signal during electron irradiation of a sample in SEM.

Feature of secondary ion emission at various temperature of irradiated copper single crystal

The difference between the forms and positions of the maximum of the energy spectrum of secondary 63Cu+ ions emitted from the (100) face of a Cu single crystal in close-packed <110> directions and between them at different target temperatures is revealed. For a sample at room temperature, it is established that the most probable ion energy Emax and the width h of the energy spectra at half-height increase with the polar emission angle, θ, measured from the normal to the surface. The opposite tendency, namely, a decrease in Emax with increasing θ, is obtained for ions emitted from a single crystal heated to several hundred degrees Celsius. Based on modern models of secondary ion emission, the observed regularities, which must be taken into account in the theoretical description of the process and in the practical application of secondary ions in mass spectroscopy, are discussed.

Calculation of the electronic structure of metal island films

The aim of our paper is to study the electronic structure of metal island films as examples of a nanosystem. Because the electronic structure is discrete, the charge exchange between atomic particles and nanosystems exhibits quantum-dimensional effects. We calculated the electronic structure of thin island films, which is required for solving and analyzing the problem of charge exchange with the film. The typical island dimensions are also estimated; in the case of dimensions exceeding them, the discreteness of the electronic structure becomes unimportant and quantum-dimensional effects disappear.

Influence of the magnetic phase transition on secondary ion emission from disordered Ni-Pd compounds of various compositions

Variations in secondary ion emission (SIE) from polycrystals of ferromagnetic disordered Ni-Pd compounds irradiated by argon ions with energy of 10 keV are studied experimentally. A considerable reduction in Ni+ and Pd+ ion emission upon transitioning from the ferromagnetic to the paramagnetic state is revealed for the following Ni-Pd compounds with various Curie points TC: NiPd (TC = 190°C), Ni5Pd (TC = 315°C), and NiPd5 (TC = 110°C). The observed reduction in SIE is attributed to variations in the surface binding energy and the density of electron states near the Fermi level.

Peculiarities of electron exchange between a negative hydrogen ion and atomic chains

This paper is dedicated to studying electron exchange between a negative hydrogen ion and an atomic chain with subsequent electron transport along the linear chain of hydrogen atoms. This process occurs after the electron transition from the negative hydrogen atom to the atomic chain. In our calculations, a method of wave packet propagation not using perturbation theory was applied. It is shown that the effectiveness of electron transport decreases uniformly as the distance from the ion to the chain increases. The electron propagates along the chain uniformly; in this case, the electron velocity is almost independent of the ion-chain distance.