Electron solvation dynamics in I−(NH3)n clusters

Abstract

Femtosecond photoelectron spectroscopy (FPES) is used to monitor the dynamics associated with the excitation of the charge-transfer-to-solvent (CTTS) precursor states in I⁻(NH₃)_n=4–15 clusters. The FPE spectra imply that the weakly bound excess electron in the excited state undergoes partial solvation via solvent rearrangement on a time scale of 0.5–2 ps, and this partially solvated state decays by electron emission on a 10–50 ps time scale. Both the extent of solvation and the lifetimes increase gradually with cluster size, in contrast to the more abrupt size-dependent effects previously observed in I⁻(H₂O)_n clusters.