Ring inversion of dihydronaphthalene by laser-induced fluorescence in a supersonic jet

The laser-induced fluorescence excitation (FE) and the single vibronic level fluorescence (SVL) emission spectra of 1,2-dihydronaphthalene have been studied in a pulsed supersonic jet. The 128 cm-1 progression in FE and the 140 cm-1 progression in SVL have been assigned to the low-frequency large-amplitude torsional motion between the two symmetry-related non-planar conformations of the excited and the ground states, respectively. Comparison of frequencies and intensifies with corresponding values calculated from a model double-well potential leads to a barrier height of 640 cm-1 for the excited state and greater than 1000 cm-1 for the ground state