Laser-induced fluorescence, electronic absorption, infrared and Raman spectra, and ab initio calculations of 1,2-dihydronaphthalene: Investigation of the out-of-plane ring modes for the ground and S1(π,π*) excited states

Abstract

The laser-induced fluorescence spectra and dispersed fluorescence spectra of jet-cooled 1,2-dihydronaphthalene have been analyzed to investigate the ring inversion process in both the S0 and S1(π,π*) excited states. Ultraviolet absorption, infrared, and Raman spectra were also recorded to complement the analyses. Ab initio calculations predict the inversion process to involve four out-of-plane ring motions, and linear combinations of these were made to model the inversion process. The data show the barrier to inversion in the ground state to be 1363±100 cm−1 (the triple-zeta ab initio value is 1524 cm−1). The experimental data indicate that the barrier increases substantially in the excited state, for which the calculated barrier is 1526 cm−1 with a CIS/6-311+G(d) basis set.