MICROSCOPIC SOLVATION PROCESS OF SINGLE LI ATOM IN SMALL WATER CLUSTERS

We examine the photoelectron spectra of negatively-charged water clust ers containing a Li atom, Li-(H2O)(n) (n less than or equal to 10), to reveal the hydration state of the Li atom in water clusters. The S-2- and P-2-type transitions of Li are found to be shifted to the lower e lectron binding energy with increasing cluster size up to n = 4 and th en shift back to higher binding energy for n greater than or equal to 5. We discuss these results in relation to the spontaneous ionization of the Li atom and the formation of two-center ion-pair state, which i s a counter part of hydrated electron. (C) 1998 Elsevier Science B.V. All rights reserved.