An objective that is important to chemistry is the determination of the T1, relaxation pathway. in recent time-resolved Raman experiments we have discovered that large—nonstatistical-—fractions of the N-H vibrational excitation of pyrrole are found later In the C–C stretch excitation. It was also shown that the relaxation pathway is intermolecular so that collisions induce the transfer of vibrational energy between neighboring molecules of pyrrole. By using benzene as a solvent we also showed that the N-H excitation energy flows quite efficiently into the benzene ring mode at 992 cm-1. The energy flow in this case is critically dependant on the preferred geometric structures In solution in which the N-H group is weakly bonding with the II-electron system of a neighboring molecule. Studies in glasses show that the vibrational dynamics are heterogeneous.
© 1989 Optical Society of AmericaPDF Article