Mode specific vibrational kinetics after intramolecular electron transfer studied by picosecond anti-Stokes Raman spectroscopy

Picosecond vibrational relaxation initiated by intramolecular electron back -transfer of Betaine 30 in propylene carbonate is studied by time-resolved anti-Stokes Raman scattering. We demonstrate for the first time distinct no nequilibrium populations of vibrational modes in the electronic ground stat e that persist up to 10 ps. The strongest Raman band at 1607 cm(-1) exhibit s a rise time close to the electron transfer time of 1 ps, suggesting that this mode is involved in electron transfer. Vibrations between 400 and 1400 cm(-1) display slower rise times. Quasi-equilibrium populations of the Ram an active modes are established after 10 ps. (C) 1999 Elsevier Science B.V. All rights reserved.