Knowledge Bank

Intramolecular vibrational redistribution after initial excitation of levels with $cvib$ ranging from $1251cm-1$ to $3320cm-1$ in $S1$ p-difluorobenzene (pDFB) has been studied by observation of the time evolution of the $S1\to S0$ fluorescence spectrum. Evidence for redistribution is observed for all but the $1251cm-1$ level. Fluorescence observed after the natural lifetime of pDFB is congested and near featureless at large $cvib$ due to redistribution. Fluorescence at short times (tens of psec) shows substantial structure that is consistent with emission from the level initially reached in excitation. Details of the redistribution kinetics will be discussed.