Some Features of the Electron Exchange between Ions and a Metal Surface Caused by its Atomic Structure
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eatures of the Electron Exchange between Ions and a Metal Surface Caused by its Atomic Structure A. F. Aleksandrova, I. K. Gainullina, *, and M. A. Sonkinb aMoscow
b
State University, Moscow, 119992 Russia Tomsk Polytechnic University, Engineering School of Information Technologies and Robotics, Tomsk, 634034 Russia *e-mail: [email protected] Received December 16, 2019; revised January 4, 2020; accepted January 17, 2020
Abstract—Some features of the electron exchange between ions and a metal surface caused by its atomic structure are studied. The simulation is based on three-dimensional implementation of the wave-packet propagation method using pseudopotentials describing the metal at the atomic level. Three-dimensional pseudopotentials for the Cu(100), Cu(110), and Cu(111) surfaces, which reproduce well-known electronexchange regularities well, are constructed using density functional theory. When considering the model “static” problem, it is shown that the lateral position of an ion weakly affects the main characteristics of the electron exchange and ion propagation along one of the directions in the crystal. However, three-dimensional pseudopotentials taking the atomic structure of the metal into account make it possible to obtain a more realistic picture of the electron transition than widely used one-dimensional model pseudopotentials. For example, when simulating grazing scattering with the use of one-dimensional pseudopotentials, the electron retains the parallel velocity component after the passing to the metal, which is contrary to fact. If threedimensional potentials are used, then the parallel component of the electron velocity in the metal decreases, which is more correct. Keywords: ion–surface interaction, electron exchange, computer simulation, three-dimensional calculations, atomic structure DOI: 10.1134/S1027451020040205
INTRODUCTION Investigation of the charge (electron) exchange upon the interaction of atomic particles with solid surfaces is of fundamental and applied interest for several fields of physics and chemistry. For fundamental science, charge exchange is of interest when studying scattering, sputtering, adsorption, and molecule dissociation [1–3]. The practical importance of electron exchange is due to various applications, including the miniaturization of semiconductor electronics using the deposition of thin films, reactive ion etching, catalysis, and the modification and analysis of surfaces (SIMS) [2, 4–7]. Resonant electron tunneling plays an important role in studying the charge exchange between an atomic particle and a metal surface [8–19]. If there are no energy restrictions, then it is this process that dominates in the charge exchange, because its probability is larger than that of nonresonant transitions and Auger processes. In this paper, we numerically study the resonant charge exchange between ions and metal surfaces. It is shown that taking the atomic structure of the surface
into consideration has a significant influence on electron exchange in some cases.
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