Intramolecular proton transfer in asymmetric double minimum potential functions

Excited singlet state proton transfer has been demonstrated in hydroxy-substituted anthraquinones via the technique of laser induced fluorescence. Both low temperature Shpol'skii matrix and free jet sample environments have been used. A comparison of vibronic intensity patterns shows the proton transfer to be largely invariant to the sample environment. Well defined rotational contours are observed in the free jet excitation spectra. Phosphorescence spectra have also been measured for some of these molecules and these indicate that the S₁ and T₁ states probably have very different potential functions for the hydrogen bond.