Evolution of the Energy and Angular Distributions of Emitted Atoms with a Variation in the Atomic Number of the Target S
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ion of the Energy and Angular Distributions of Emitted Atoms with a Variation in the Atomic Number of the Target Substance V. N. Samoilova, * and A. I. Musinb a
bMoscow
Moscow State University, Faculty of Physics, Moscow, 119991 Russia Region State University, Faculty of Physics and Mathematics, Moscow, 105005 Russia *e-mail: [email protected]
Received November 16, 2019; revised December 30, 2019; accepted January 21, 2020
Abstract—The emission of atoms from the (001) faces of a series of real and model single crystals is studied using computer simulation by means of the molecular-dynamics method. The evolution of the energy distributions of atoms sputtered from surfaces with polar and azimuthal-angle resolution is studied in the case of a variation in the atomic number of the target substance. For low energies, the maximum of overfocused sputtered atoms is more sensitive to a variation in the atomic number of the material substance than that of focused atoms. The evolution of polar-angle distributions of atoms sputtered from surfaces with energy and azimuthal-angle resolution is also studied in the case of a variation in the atomic number of the target substance. The maxima of the focused and overfocused sputtered atoms are very sensitive to a variation in the atomic number of the target substance. The observed shifts of the maxima are related to enhancement of the blocking effect as the atomic number of the target substance increases. Keywords: single-crystal sputtering, emission of atoms from a surface, energy distribution of sputtered atoms, polar-angle distribution, focused atoms, overfocused atoms, molecular-dynamics method DOI: 10.1134/S1027451020040151
INTRODUCTION Recently, interest in effects occurring under the ion bombardment of target surfaces, including the sputtering of solids by means of ion bombardment, has increased significantly. This is related to a great number of applications where sputtering under ion bombardment plays a noticeable role [1]. We note the role of the sputtering process in modern methods for analyzing the structure and elemental composition of the surface, namely, secondary ion mass spectrometry (SIMS) and secondary neutral mass spectrometry (SNMS), and the role of processes under ion bombardment in destroying the first wall of a thermonuclear reactor. This interest is also due to the development of theoretical models and especially computer simulation, which successfully describe experimentally observed peculiarities and predict new regularities of sputtering process. Progress in studying the sputtering process is closely related to the development of experimental and theoretical works. In this case, the role of computer simulation in clarifying mechanisms determining the peculiarities observed in experiments using the ion bombardment of solid surfaces turns out to be very significant. Recent successful studies of segregation [2– 6], molecular-dynamics calculations of the sputtering of single crystals and polycrystals with different struc-
tures and compositions [7
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