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 e lectron kinetic energy (ZEKE) spectroscopy, and ab initio calculations. Hol e-burning spectroscopy was employed to confirm the presence of three isomer s in the REMPI spectrum. The frequencies of the intermolecular vibrations a nd the S(1)0(0) and ionization energy red shifts reveal that the water mole cule hydrogen bonds more weakly to resorcinol than phenol. We discuss the s pectral characteristics of the rotational isomers by considering the extent to which the second OH group of resorcinol perturbs the resorcinol . H2O h ydrogen bond.