EXPERIMENTAL AND THEORETICAL INVESTIGATIONS OF IONIZATION-POTENTIALS AND STRUCTURES OF MIXED SODIUM-LITHIUM CLUSTERS

We have measured the ionization potentials (IP) of Nan-mLim clusters ( 3 less than or equal to n less than or equal to 21 and 1 less than or equal to m less than or equal to 3) generated in a supersonic beam. Th e IPs of mixed clusters are dose to the values obtained for pure sodiu m and pure lithium clusters. They display the features of a metallic s ystem with n delocalized electrons. For clusters containing 2-6 atoms, we have performed density functional theory calculations. The IPs cal culated for the lowest-energy structures are in good agreement with ex periment. The geometries of the heteronuclear clusters, in particular the 2D-3D transition, are discussed in detail. (C) 1998 Elsevier Scien ce B.V. All rights reserved.