Excitation spectra of 2,5hyphen;dihydroxyhyphen;phyphen;benzoquinone monomer and hydrates

摘要

The fluorescence excitation spectrum of the lowest allowed singletndash;singlet transition of jethyphen;cooled 2,5hyphen;dihydroxyhyphen;phyphen;benzoquinone is reported. The transition is assigned asS3larr;S0,1Bularr;1Ag, pgr;ast;larr;pgr; and the 0ndash;0 band origin is at 275.55 nm. Twenty vibrational levels, which include half of theAgfundamentals, are assigned for theS3state. The observed laserhyphen;induced fluorescence transitions are structureless peaks with bandwidths that depend on the intensity of the excitation laser. No spectral multiplets attributable to intramolecular tunneling were observed. Deuterium isotope shifts of the 0ndash;0 transition are +21 cmminus;1per internal hydrogen bond. The 0ndash;0 transitions of hydrate isotopomers with hydration shifts of only +11 cmminus;1per water molecule are reported.