Observation of the intramolecular charge transfer process in 4-dimethylamino-4'-nitrostilbene by time-resolved CARS spectroscopy

Charge Transfert (CT) process of 4-dimethylamino-4'-nitrostilbene in soluti on has been studied by "pump-probe" and transient CARS experiments with a 1 ps time resolution. While "pump-probe" experiments give good evidence for formation of CT state in polar solvent, CARS experiments reveal structural changes associated to CT process. In acetonitrile, a 37 cm(-1) downshift of the NO2 stretching mode is assigned to conformational relaxation of the In ternal. Charge Transfer state. In toluene such behavior is not observed cor related to the absence of CT stabilization in non-polar solvent.