Photodetachment and Photofragmentation Studies of Semiconductor Cluster Anions

摘要

Silicon, germanium, and gallium arsenide negative cluster ions are produced by laser vaporization followed by free supersonic expansion. Electron affinities (EA) of the corresponding neutral clusters are roughly bracketed by measuring the fluence dependence for photodetachment from anions at discrete probe laser wave-length (above the photodetachment threshold the dependence on fluence is linear, below it is quadratic). An even/odd alternation is found in the negative ion distribution with gallium arsenide clusters with an odd number of atoms having higher EA's than their even neighbors. This suggests that the surfaces of the even clusters are extensively restructured in a way which eliminates dangling chemical bonds.