ELECTRON PHOTOEJECTION AND RELATED PHENOMENA IN SOLUTIONS - ULTRAFAST LASER PHOTOLYSIS STUDIES

Dynamics and mechanisms of photoionization and related phenomena in the solution phase are discussed in relation to the results of picosecond transient absorption measurements. Monophotonic ionization of aromatic diamines from their fluorescent state was first established by us by means of picosecond time-resolved laser spectroscopy. We have examined its mechanism in some details and have demonstrated that it should be the consequence of large energy fluctuation caused by cooperative motion of solvent molecules surrounding the excited diamines. Electrons ejected from their parent molecules in alcoholic solvents are stabilized and form solvated electrons. Partially solvated electrons of which spectra are red shifted compared with fully solvated electrons play a key role to elucidate the solvation mechanism. Electron-cation geminate recombination in nonpolar solvents are investigated recently by more direct methods of time-resolved transient absorption spectral measurements.