THE PHYSICS OF SIMPLE METAL-CLUSTERS - EXPERIMENTAL ASPECTS AND SIMPLE-MODELS

The study of simple metal clusters has burgeoned in the last decade, m otivated by the growing interest in the evolution of physical properti es from the atom to the bulk solid, a progression passing through the domain of atomic clusters. On the experimental side, the rapid develop ment of new techniques for producing the clusters and for probing and detecting them has resulted in a phenomenal increase in our knowledge of these systems. For clusters of the simplest metals, the alkali and noble metals, the electronic structure is dominated by the number of v alence electrons, and the ionic cores are of secondary importance. The se electrons are delocalized, and the electronic system exhibits a she ll structure that is closely related to the well-known nuclear shell s tructure. In this article the results from a broad range of experiment s are reviewed and compared with theory. Included are the behavior of the mass-abundance spectra, polarizabilities, ionization potentials, p hotoelectron spectra, optical spectra, and fragmentation phenomena.