Torsional potential function of phenyl acetate in the S-1 state as studiedby fluorescence excitation spectroscopy in a supersonic free jet

The S-1 <-- S-0, fluorescence excitation spectra of jet-cooled phenyl aceta te were measured. The 0-0 band was observed at 37553 cm(-1), and short prog ressions with intervals of about 45 cm(-1) were assigned to the Ph-O torsio nal mode. The progression starting at the 0-0 band was analyzed with the ai d of CIS/6-31 + G(D) calculations, from which the torsional potential funct ion in the S-1 state was derived to be V(phi) = V-2(1 - cos2 phi)/2 + V-4(1 - cos4 phi)/2, where V-4 = -281 +/- 7 cm(-1). using V-2 = 96 cm(-1) derive d from ab initio calculations. (C) 2000 Elsevier Science B.V. All rights re served.