Author:

Keywords:

fine-structure states, quantitative measurements, resonant photoionization, ni atoms, ionization, population, surface, Science & Technology, Technology, Physical Sciences, Instruments & Instrumentation, Nuclear Science & Technology, Physics, Atomic, Molecular & Chemical, Physics, Nuclear, Physics, FINE-STRUCTURE STATES, QUANTITATIVE MEASUREMENTS, RESONANT PHOTOIONIZATION, NI ATOMS, IONIZATION, POPULATION, SURFACE, 0202 Atomic, Molecular, Nuclear, Particle and Plasma Physics, 0402 Geochemistry, 0915 Interdisciplinary Engineering, Applied Physics, 5104 Condensed matter physics, 5106 Nuclear and plasma physics

Abstract:

This paper deals with the investigation of electronic processes involved in the emission of neutral atoms during keV ion-beam sputtering of metals, We first present an experimental study of Ar+ ion-beam sputtering of clean, polycrystalline metals. Atoms emitted in the ground and metastable states are probed using double-resonant laser ionization. These efficient probing schemes allow the quantitative determination of population partitions as well as state-specific, kinetic-energy (KE) distributions. Experimental data on the sputtering of Co, Ni, Cu, Sr and Ag are reported. In the second part of this article it is shown that the en-.Lission of neutral atoms during sputtering of metals can be modelled as follows: as a result of the collision cascade created by the incoming particles, a sputtered particle escapes from the surface as a positive ion and becomes neutralized by resonant transfer of an electron from the valence band of the metal. A qualitative description of this multichannel electron transfer process is given, explaining the main observations of these sputtering studies. (C) 2001 Elsevier Science B.V. All rights reserved.