Time-resolved dynamics of charge transfer to solvent states in solvated iodide clusters

The dynamics of the cluster precursors to charge-transfer-to-solvent (CTI'S) states have been studied in clusters of iodide with xenon, water, D2O, ammonia and methanol using femtosecond photoelectron spectroscopy. The dynamics of these states differ dramatically according to solvent type and number. Excitation of the lower CTTS state in I-(Xe)(n) clusters yields a state that is stable over the time scale of the experiment (similar to 200 ps), whereas the upper spin-orbit state decays by spin-orbit autodetachment within 500 to 1000 fs, depending on the number of Xe atoms. The hydrogen-bonded clusters show evidence for partial solvation of the excess electron following CTTS excitation. In general they exhibit more complicated dynamics which correspond to internal rearrangement in one or more electronic states. A description including isomerization and electron solvation is given for the I-(D2O)(n) clusters, and compared to the dynamics observed in I-(NH3)(n) and I-(CH3OH)(n) clusters. (C) 2000 Elsevier Science B.V. All rights reserved.