DIET in highly charged ion interaction with silicon surfaces

We have observed mass spectra of desorbed ions from a clean and a hydrogen terminated silicon surfaces by the impact of highly charged ions (Xeq+, q = 26, 34, 44 and 50). The released ions mainly consist of proton for both surfaces, and the quantum yield of proton desorption for hydrogen terminated surface exceeds unity. It is seemed that charge state dependence of ion yield roughly follows q5 rule reported by Kuroki et al. in the experiments for lower charge states.