SOLVATION DYNAMICS OF ELECTRON EJECTED BY PHOTOIONIZATION OF PARA-PHENYLENEDIAMINE IN SEVERAL ALCOHOLS - TEMPERATURE EFFECT STUDIED BY PICOSECOND TRANSIENT ABSORPTION-MEASUREMENTS

Dynamic behavior of the electron ejected by two photon ionization of p-phenylenediamine in several alcohols has been investigated by picosecond transient absorption measurements in the temperature range from -90 to 23-degrees-C. The time dependence of the transient absorbance has been measured carefully at various wavelengths, and it has been confirmed that the solvation process of the electron is characterized by two time constants. One is similar to tau-D2, the dielectric relaxation time for rotation of the monomer alcohol, and the other is well correlated to tau-Ll, the longitudinal relaxation time accompanying hydrogen bond breaking over a wide range of temperatures. These results indicate strongly that the formation of solvated electron, e(s)-, cannot be described by the simple two-state model, e(t)- --> e(s)-. A partially solvated intermediate state, e(ps)-, should be involved in the formation of solvated electron. The solvation of electrons is initiated by the reorientation of alcohol monomer in the first solvation shell, and the polarization of the outer shell is established later.