NAXAU AND CSXAU BIMETAL CLUSTERS - FINITE-SIZE ANALOGS OF SODIUM-GOLDAND CESIUM-GOLD COMPOUNDS

Mixed metal clusters of sodium and cesium with gold have been generate d in a supersonic expansion from the mixed vapor phase. Their tendency towards binary cluster formation, relative thermodynamic stability, a nd ionization potentials have been experimentally and computationally investigated. The properties of the NaxAu clusters may be understood w ithin an electronic shell model based on delocalized cluster orbitals, whereas the characteristics of CsxAu are indicative of substantial io nic interactions. Relativistic density functional calculations have be en performed to elucidate the cluster electronic structure and to rati onalize observed properties which may not be accounted for by the jell ium model. The properties of these finite-size clusters are shown to b e related to the known bulk intermetallic compounds sodium-gold and ce sium-gold (cesium aurid), respectively. (C) 1996 American Institute of Physics.