Study of Cun and Cun+ (n = 1,2,3) cluster formation under ion bombardment

Yields and energy spectra of neutral and charged particles sputtered from Cu target under 5.5 keV Ar+ ion bombardment have been measured. The yield of Cun neutrals falls off rapidly with increasing n that can be explained by the recombination model. The yield of Cun+ ions depends unmonotonously on n. The ionization probability of sputtered particles is described by an exponential dependence exp[-(In-φ)/ε0], where In is the ionization potential of Cun cluster, φ is the work function and ε is a parameter. (author)