S-1 EXCITATION AND ZERO KINETIC-ENERGY SPECTRA OF PARTLY DEUTERATED 11 PHENOL-WATER COMPLEXES/

Two-photon, two-color resonant-enhanced multiphoton ionization (REMPI) spectra of the S-1 state of isotopic 1:1 hydrogen-bonded phenol-water clusters have been recorded. Up to three deuterium atoms are introduc ed in the phenolic OH group and/or the water molecule. The intermolecu lar vibrational structure found is in reasonable agreement with previo usly reported one-color REMPI spectra, however, a partly different int erpretation of the spectra is presented here. Zero kinetic energy phot oelectron (ZEKE) spectra have been obtained via different intermediate S-1 levels of the various isotopic complexes. The analysis of both th e REMPI and the ZEKE spectra supports the new assignment of several vi brational bands observed in the REMPI spectra of the deuterated comple xes where one or two hydrogen atoms are substituted by deuterium. For these deuterated complexes, the reassignment given here is based on th e assumption that two different nonequivalent isomeric configurations are responsible for the structure observed in the REMPI spectra. This result is in clear contrast to the previously given interpretation whe re the spectra were analyzed in terms of only one isomer and the occur rence of Fermi resonances. Furthermore, accurate ionization energies a re determined for all possible isomers of the Various isotopic complex es and propensity rules for these values as a function of site-specifi c deuteration have been found. In addition, the analysis of the interm olecular vibrational structure of the complex cations confirmed the as signment of the intermolecular stretch vibration.