AB-INITIO PREDICTIONS OF STRUCTURAL AND OPTICAL-RESPONSE PROPERTIES OF NA-N(- INTERPRETATION OF DEPLETION SPECTRA AT LOW-TEMPERATURE() CLUSTERS )

We show that a comparison of the depletion spectra of Na-n(+) (n=2-9,1 1,21) clusters recorded at low temperature and optically allowed trans itions determined for the stable structures using ab initio methods ac counting for electron correlation allows the assignment of the cluster geometry to the measured features. Due to the large mobility of atoms in alkali metal clusters, the influence of temperature on structural and electronic properties is significant. The lowering of temperature reveals new spectroscopic features which are structure dependent. Opti cal response properties of small cationic Na-n(+) clusters are charact erized by rich molecularlike spectroscopic patterns, also with increas ing size, and differ substantially from those found for neutral cluste rs. It has been clearly demonstrated that not only the number of valen ce electrons but its mutual interplay with the geometric properties de termine optical response features. (C) 1996 American Institute of Phys ics.