EVIDENCE FOR INTERMOLECULAR HYDROGEN-BOND REARRANGEMENT IN THE ELECTRON-TRANSFER DYNAMICS OF BETAINE-30 IN N-BUTANOL

The electron transfer and ground-state solvation dynamics of betaine-3 0 (B-30) in n-butanol at low temperatures are investigated by femtosec ond pump-probe spectroscopy. Two separate components of the solvent re sponse to solute excitation are observed. At higher temperatures (292- 273 K), spectral evolution corresponding to diffusional solvation is e vident. However, low-temperature studies (273-193 K) show the presence of a second process characterized by a approximate to 100 ps decay ti me and weak temperature dependence demonstrating that specific intermo lecular hydrogen-bond dynamics are involved in the solvation of B-30 i n protic solvents.