PICOSECOND DYNAMICS OF BENZOPHENONE ANION SOLVATION

The dynamics of benzophenone anion solvation in alcohols are studied by pulse-radiolysis techniques. The solvation process is characterized by the blue shift of the transient absorption spectrum of the anion and is faster for the smaller alcohols. The anion is solvated more slowly than the electron in the same solvent, but the solvation times of both are similar to tau2, the solvent dielectric relaxation time. The familiar phenomenological ''two-state'' model of solvation was found to be inappropriate for describing the anion solvation process. A multistate process appears to be a more appropriate description. We modeled the kinetics of the spectral relaxation. In most cases, nearly quantitative agreement between the calculated and observed spectra is achieved. The characteristic relaxation times for the alcohol solvents around the anions were also reproduced.