Observation of hydrogen-bonded rotational isomers of the resorcinol water complex

Three rotational isomers of resorcinol(1,3-dihydroxybenzene). H2O have been identified using resonance-enhanced multiphoton ionization (REMPI), zero electron kinetic energy (ZEKE) spectroscopy, and ab initio calculations. Hole-burning spectroscopy was employed to confirm the presence of three isomers in the REMPI spectrum. The frequencies of the intermolecular vibrations and the S(1)0(0) and ionization energy red shifts reveal that the water molecule hydrogen bonds more weakly to resorcinol than phenol. We discuss the spectral characteristics of the rotational isomers by considering the extent to which the second OH group of resorcinol perturbs the resorcinol . H2O hydrogen bond.