Ionization of noble gases by light ion impact: Scaling the ionization cross section

Abstract

Single ionization is the dominant channel for fast ion impact of multi-electron targets. This channel plays a major role in the modeling of several processes connected to the penetration of swift ions in solids, such as radiation damage, energy loss, sputtering, desorption, etc. This variety of applications makes having a scaling law for target ionization useful. The major difficulty in obtaining such a scaling lies in the fact that single ionization involves essentially the outermost electrons of the target, which have quite different wavefunctions if different atoms are considered. In this paper we used recent measurements of single-ionization of noble gases by He+ ions together with previous data for proton and electron ionization to show that a consistent scaling law can be obtained for the single ionization of noble gases. A theoretical support of this scaling is also presented.