Neutralization of Low Energy Helium Ions Scattered From Gold Adatoms on Si(111)- root 3 x root 3-Au

The neutralization of 5 keV He exp + ions scattered from Au adatoms on the Si(111)- root 3 x root 3-Au surface was studied by impact-collision ion-scattering spectroscopy (ICISS). The He exp + ICISS data contained false shadowing features that were actually the result of local neutralization effects. The radially dependent ion--atom neutralization theory of Woodruff (1980-1982), when used in simulations of the ion scattering results, was reasonably successful in describing the neutralization of the He exp + ions by the Au atoms. Good agreement for both the (112) and (110) azimuths was obtained for a neutralization rate R = Aexp(--ar), where A and a are 15.5 fs exp --1 and 1.94 A exp --1 , respectively. An Auger neutralization model assuming a planar ion solid interaction aurface was also tested, yielding much poorer agreement. 19 ref.--AA