A REMPI investigation of the minimum energy conformations of diphenyl ether

The structure and low-frequency vibrations of jet-cooled molecules of diphenyl ether are studied with the resonance-enhanced two-photon ionization technique. The origin for the S1 S0 transition is assigned at 35,873 cm^-1 and, within 400 cm^-1, the vibrational progressions suggest the existence of different conformations proposed for this molecule. A potential energy surface for the ground state, obtained with the use of group theory, is checked against the conformational energy surface given by molecular mechanics simulations.