SOLVENT EFFECTS IN THE $(n \to \pi^{*}) (T\to S)$ EMISSION SPECTRUM OF PYRAZINE

Abstract

The $(n \to \pi^{*})$ $T\to S$ Spectra of pyrazine has been measured at. $77^\circ K$ in hydrocarbon and EPA glasses. A comparison with the absorption $(S\to S^{1})$ data in the same media at $77^\circ K$ indicates the importance of the Franck-Condon principle in the Solvent shift. It is suggested that the n orbitals expand on $n \to \pi^{*}$ emission and a Franck-Condon Strain results from this expansion. The role of this Franck-Condon Strain on $n \to \pi^{*}$ transitions in general will be discussed. The determination of the polarization of the $T\to S$ Spectra of pyrazine is in progress and will be reported.