Low-Energy Sputtering Yields in Hg

Abstract

Further data on sputtering yields for normally incident ${\mathrm{Hg}}^{+}$-ion bombardment in the energy range of 50 to 400 ev have been collected. Experimental data are used to determine the influence of atomic weight and heat of sublimation of the target material and to establish an empirical sputtering relation. Results provide strong support for a picture of sputtering which might be termed "playing three-dimensional billiards with atoms." The degree of filling of the inner shells, especially the $d$ shells, determines how closely collisions approximate hard-sphere collisions. Energy is transferred most efficiently in metals with completely filled $d$ shells. Accordingly, Cu, Ag, and Au have the highest sputtering yields. Results for ${\mathrm{Hg}}^{+}$-ion bombardment support theories developed by Langberg and by Silsbee but disagree with a theory published by Henschke. Conditions may be different, however, for the case of bombardment with light ions such as hydrogen or helium.The sputtering yields of alloys do not seem to differ substantially from those of their main constituents.