Characterization of the local binding motifs in two of the three isomeric classes of hydrated electron clusters

PHYS 76

Mark A. Johnson, Department of Chemistry, Yale University, P.O. Box 208107, New Haven, CT 06520-8107
Attachment of an excess electron to water clusters presents an interesting possibility to study the formation the "hydrated electron" from a molecular perspective. Recent studies have highlighted the role of surface and internal states for electron accommodation, which are readily distinguished by their different electron binding energies. In this paper, we use co-variance mapping in addition to argon solvation to deconvolute the vibrational spectra of the two different isomer families in the small size regime. The more strongly bound clusters share a common binding motif, in which one water molecule is oriented with both of its hydrogen atoms directly into the electron cloud. The more weakly bound isomer does not display this motif, but rather appears to involve electron attachment to several dangling hydrogen atoms associated with water molecules in acceptor-donor H-bonding sites. Interestingly, both of these motifs are surface states at small size, and we discuss the evolution of these motifs into the larger size regime thought to be more appropriately described as internal states.