Secondary-electron yield from Au induced by highly charged Ta ions

The total electron yields, gamma, for the emission of electrons induced by the impact of Taq+ (11 less than or equal to q less than or equal to 41) io ns with kinetic energy per charge from 15 to 150 keV/q on clean polycrystal line Au are presented. The experimental data are analyzed with use of the r elations gamma(theta) = y(0) cos(-f)theta and gamma(theta) = gamma (above) + gamma (below)cos(-1)theta. Fits of experimental data give a range of f fr om similar to0.6 to similar to0.17 and ratio gamma (above)/gamma (below) > 1. The analysis also shows that the above-surface electron yield, gamma (ab ove) strongly depends on the charge state (gamma (above approximate to) q) and the below one, ii,,,,,, is proportional to the ion impact velocity (gam ma (below) approximate to v). The correction of cos(-1)theta -dependence fo r fit improvement is discussed. (C) 2001 Elsevier Science B.V. All rights r eserved.