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Amusia M.Y.,Hebrew University of Jerusalem | Amusia M.Y.,RAS Ioffe Physical - Technical Institute | Baltenkov A.S.,Hebrew University of Jerusalem | Baltenkov A.S.,Arifov Institute of Electronics
Central European Journal of Physics | Year: 2010

We demonstrate, using a simple model, that, in the frame of muffin-tin-like potential, non-physical peculiarities appear in molecular photoionization cross-sections that are a consequence of "jumps" in the potential and its first derivative at some radius. The magnitude of non-physical effects is of the same order as the physical oscillations in the cross-section of a diatomicmolecule. The role of the size of these "jumps" is illustrated by choosing three values for it. The results obtained are connected to the previously studied effect of non-analytic behavior as a function of r, the potential V(r) acting upon a particle on its photoionization cross-section. In reality, such potential has to be analytic in magnitude and have a first derivative function in r. The introduction of non-analytic features in model V(r) leads to non-physical features - oscillations, additional maxima, and so forth - in the corresponding cross-section. © 2009 Versita Warsaw and Springer-Verlag Berlin Heidelberg.

Isakhanov Z.A.,Arifov Institute of Electronics
Journal of Surface Investigation | Year: 2013

The angular and energy distributions of alkaline Na+ and K+ ions which have passed through thin Cu films in different crystal states are studied. The ion energy E0 is varied from 10 to 40 keV, and the incidence angle. ranges from 0° to 60°. The angular aperture of the detector is ∼0.5°, which allows the form of the angular distribution of ions which have passed through the solid thin films as a function of the energy, the angle of primary-ion beam incidence, and the layer thickness to be studied in detail. It is shown that, in the range E0 = 10.40 keV, the energy loss ΔE of those ions that have passed increases linearly as the energy of incident ions increases. The energy loss increases with increasing ion mass in the case of singly charged ions. The surface amorphization of single- and polycrystalline films leads to an increase (by 150-200 eV) in the energy loss caused by the diffuse propagation of ions and to loss-peak broadening. It is probable that surface amorphization is accompanied by an increase in the number of atoms experiencing multiple collisions with atoms of the film, which leads to an increase in the average energy loss by ions that have passed through films. © 2013 Pleiades Publishing, Ltd.

Amusia M.Y.,Hebrew University of Jerusalem | Amusia M.Y.,RAS Ioffe Physical - Technical Institute | Baltenkov A.S.,Arifov Institute of Electronics
JETP Letters | Year: 2011

The special features of magneto-dipole photoionization of atomic s states are analyzed and the possibilities of experimental observation of this effect are discussed. It has been shown that despite the smallness of total cross sections for magnetic processes as compared with electric-dipole ones, the experimental observation of magnetic effects is possible, in principle, if photoelectrons are detected in the directions perpendicular to both the polarization vector of photon and its momentum; i. e. in the directions where the differential cross section for electric-dipole ionization of atomic s states is close to zero. The capabilities of the derived general formulas for the magneto-dipole cross sections are illustrated by numerical calculations for s subshells of He and Be atoms. © 2011 Pleiades Publishing, Ltd.

Baltenkov A.S.,Arifov Institute of Electronics | Becker U.,Fritz Haber Institute | Manson S.T.,Georgia State University | Msezane A.Z.,Clark Atlanta University
Journal of Physics B: Atomic, Molecular and Optical Physics | Year: 2010

Within the framework of a model representing the potential of a C 60 cage as a spherical electro-neutral layer U(r) formed by smeared carbon atoms, the effect of the details of the potential on spectral characteristics of atoms localized inside the fullerene shell has been studied. Using examples of encapsulated H and He atoms, it is shown that for potential shell thickness not exceeding 1.3-1.5 au, confinement resonance oscillations in the photoionization cross section weakly depend on the shape of the function U(r). With increasing width of the potential well, the confinement resonances in the energy dependence of the photoionization cross section disappear. In addition, it is demonstrated that displacing the doped atom from the centre of the cavity also diminishes the amplitude of the confinement resonance. © 2010 IOP Publishing Ltd.

Baltenkov A.S.,Arifov Institute of Electronics | Manson S.T.,Georgia State University | Msezane A.Z.,Clark Atlanta University
Central European Journal of Physics | Year: 2011

A comprehensive study is undertaken of angular distributions of electron knock-out from atomic targets by fast electrons with a small transfer of momentum. The general expressions for the parameters of the triple differential cross-section of impact ionization in the optical limit are derived. The calculated parameters are compared with those of the angular distribution of electrons ejected from an atom in the process of photoionization. In these processes, when the multipole transitions are involved, the one-to-one correspondence between the photoionization and impact ionization parameters disappears. The nondipole transitions lead to the backward/forward asymmetry of the angular distribution of ejected electrons that is absent in the dipole approximation for ionization by both fast electrons and photons. Using the He atom as an example, the character of the asymmetry for these two processes is qualitatively different and the backward/forward asymmetry results in macroscopic directed motion of secondary electrons accompanying the passing of a fast electron beam through gas or plasma. The general formulas for this drag current are derived and applied to gaseous He. © 2011 Versita Warsaw and Springer-Verlag Wien.

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