Solvation dynamics following electron photodetachment from I- in aqueous clusters

ELOLA MD; LARIA D

JOURNAL OF CHEMICAL PHYSICS

AMERICAN INSTITUTE OF PHYSICS

Lugar: MELVILLE, NY 11747-4501 USA; Año: 2002 vol. 117 p. 2238 - 2245

0021-9606

Equilibrium and dynamical aspects of the earliest stages of solvation following the electronic excitation of I- dissolved in aqueous clusters were investigated, using a mixed quantum-classical molecular dynamics algorithm. The systems were modeled as composed by an excess quantum charge coupled to a classical bath that includes a neutral iodine and N-w=6, 50, and 100 water molecules. In small clusters, the equilibrium solvation structures of the iodine are characterized by surface states that gradually turn into interior states as one considers larger aggregates. Electronic properties of the ground and first excited states are described. In small aggregates, both states are characterized by highly diffuse density profiles that extend well beyond the spatial extent of the aggregates. In larger clusters, the confining potential provided by the classical bath localizes the electron within the aggregates. Dynamical aspects of the solvation relaxation following a vertical excitation of the solute were also examined. In all cases, the relaxation mechanisms involve a global reorganization of the original solvation structure characterized by a gradual stabilization of the solvent-solvent interactions in detriment of a less favorable electron solvation. The overall characteristic time for the solvation is in the order of tau(s)approximate to 0.05 ps for N-w=6 and attains tau(s)approximate to0.60 ps for N-w=100.