Nuclear Instruments & Methods in Physics Research Section B-Beam Interactions with Materials and Atoms vol:182 pages:127-134
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.