LARGE ODD-EVEN EFFECT IN RBCN- CLUSTER-SIZE DISTRIBUTIONS

RbCn cluster anions have been produced by Rb sputtering of graphite. T he intensity ratio of clusters with an even number of carbon atoms to those with an odd number of carbons is much larger for RbCn- clusters than for C-n(-) clusters. Ab initio quantum mechanical calculations su ggest that this arises from RbCn electron affinities that are close to zero or negative for odd n, rather than from an enhanced odd-even alt ernation in the affinities. (C) 1996 American Institute of Physics.