On the intrinsic secondary ion emission from light metals

Abstract

Two ionization mechanisms are known to contribute to the intrinsic secondary ion emission from light metals: surface excitation by electron tunneling during the separation of an outgoing particle from the target and collisional process by Auger de-excitation of excited atoms ejected outside the target with an inner electronic vacancy. Bombardment by noble gas ions in ultrahigh vacuum of those alloys where only symmetric collisions between light atoms are effective for the subsequent ionization by collisional process, allows one to distinguish between both processes and to evaluate their respective contributions at given initial energy from the concentration dependence of the ion intensities. This method and its theoretical assumptions are presented here in detail.