Abstract

We have recently developed an ion source which is capable of producing both positive and negative semiconductor cluster ions cooled by supersonic expansion. Ions of a particular mass are selected and studied by laser photodetachment and photodissociation followed by time-of-flight mass analysis. The electron affinities (EA) of several semiconductor clusters have been measured by photodetachment threshold measurements on their negative ions. For GaAs clusters, an even/odd size alternation in EA is observed as in the ionization potentials of the neutrals, supporting the suggestion that the neutral even clusters have fully paired singlet ground states with no dangling bonds.¹,² Photodissociation studies reveal that negative silicon and germanium cluster ions fragment predominantly into 6–11 atom size clusters with 6–10 being the favorite fragmentation daughters.

© 1986 Optical Society of America