ELECTRONIC AND GEOMETRIC STRUCTURE OF ARN+ AND XEN+ CLUSTERS - THE SOLVATION OF RARE-GAS IONS BY THEIR PARENT ATOMS

Photoabsorption cross sections for Ar(n)+, 3 less-than-or-equal-to n less-than-or-equal-to 80, and Xe(n)+, 3 less-than-or-equal-to n less-than-or-equal-to 30, clusters have been measured. A single absorption maximum in the visible is observed for Ar(n)+, whose redshift with growing n is interpreted as a delocalization of the charge from a trimer to a tetramer ion. For Xe3+, two maxima, and for Xe(n)+, n greater-than-or-equal-to 5, three maxima are observed. For n greater-than-or-equal-to 5 the positive charge can localize onto either a trimer or a tetramer ion core, both surrounded by neutral atoms. The transition between the two isomers is faster than 10 ns.