Knowledge Bank

The $S1$ p-difluorobenzene-Ar (pDFB-Ar) $complex1$ has been characterized by fluorescence excitation spectra and by fluorescence spectra after pumping each of twelve $S1$ vibrational levels ranging up to $tvib=1250cm-1$. In some cases, additional fluorescence spectra were obtained with initial excitation of the Ar-ring stretch. These spectroscopies constrain the $SO$ complex well depth to be with the excited state well depth about $30cm-1$ greater. The fluorescence spectra variously contain structure from the initially pumped complex level, other complex levels, and the pDFB monomer. This structure shows that vibrational predissociation time scales are generally in the nsec range but vary modestly for different initial modes. Vibrational predissociation is in every case highly selective with respect to formation of ""product"" vibrational levels in $S1$ pDFB monomer. IVR within the $S1$ complex occurs from a few of the initial levels and appears to be highly sensitive to the level identity.