Torsional potential function of phenyl acetate in the S1 state as studied by fluorescence excitation spectroscopy in a supersonic free jet

The S1←S0 fluorescence excitation spectra of jet-cooled phenyl acetate were measured. The 0-0 band was observed at 37 553 cm−1, and short progressions with intervals of about 45 cm−1 were assigned to the Ph–O torsional mode. The progression starting at the 0-0 band was analyzed with the aid of CIS/6-31+G(D) calculations, from which the torsional potential function in the S1 state was derived to be V(φ)=V2(1−cos 2φ)/2+V4(1−cos 4φ)/2, where V4=−281±7 cm−1, using V2=96 cm−1 derived from ab initio calculations.