Excitation, Ionization, and Fragmentation of Chiral Molecules in Asymmetric Microenvironments: A Mass Resolved R2PI Spectroscopic Study.

One- and two-color, mass selected R2PI spectra of the S1 S0 transitions in the bare (R)-(+)-1-phenyl-1-propanol and its complexes with bidentate solvent mols., like the (R)-(-)- and (S)-(+)-3-hydroxytetrahydrofuran enantiomers, have been recorded after a supersonic mol. beam expansion. The one-color R2PI excitation spectra of the diastereomeric complexes are characterized by three main peaks, one red-shifted and the other two blue-shifted relative to the band origin of the most stable anti conformer of the bare chromophore. The opposite direction of these spectral shifts is ascribed to the occurrence of three different hydrogen bonded isomeric structures for each individual complex, while their different magnitude depends on the configuration of the bidentate solvent mol. as well as its specific hydrogen bond interaction center, whether the ethereal oxygen atom or the hydroxyl group. The same factors play a major role in detg. the magnitude of the phenomenol. activation barriers for the loss of an Et radical from the ionized diastereomeric complexes.