Picosecond spectroscopy of excited-state charge transfer and related phenomena

Picosecond laser spectroscopy was used to make a detailed study of the dynamics and electronic structure of excited states of intramolecular heteroexcimer systems. It was confirmed that as the polarity of the solvent increases, the charge-transfer process becomes faster and the electronic structure of the heteroexcimer becomes similar to a pair of solvated ions. An investigation was made of the photochemical dehydrogenation reaction for pyrene-secondary amine systems in a nonpolar solvent and methods of picosecond spectroscopy were used to show directly that the charge-transfer process is accompanied by proton transfer. Picosecond spectroscopy was used to investigate the mechanism of high-intensity fluorescence quenching observed when two $\pi$-electron systems are linked by a hydrogen bond. It was found for the first time that intermediate charge transfer states are found in the quenching process for naphthylamine-pyridine systems.