Conformational property of ethoxybenzene as studied by laser-jet spectroscopy and theoretical calculations

The conformational property of ethoxybenzene has been investigated by means of the laser-jet spectroscopy and the theoretical calculations. The quantum-mechanical analysis of the two-dimensional potential surfaces for the S0 and S1 states that have been obtained from the DFT and TDDFT calculations, respectively, has been carried out. Its result suggested the existence of the second conformer (gauche) in addition to the main conformer (trans) in the both states, and it was predicted that the 0–0 band of the gauche conformer would appear at about 400 cm−1 lower than that of the trans conformer. The S1 ← S0 fluorescence excitation spectrum of jet-cooled ethoxybenzene has been measured. The peak that is assignable to the 0–0 band of the second conformer has been observed, whose spectral position (red-shifted from that of the trans conformer by about 229 cm−1) is qualitatively consistent with the theoretical prediction.