MASS RESOLVED HOLE BURNING SPECTROSCOPY OF PHENOL $(H_{2}O)_{2-5}$ CLUSTERS AND ITS DEUTERATED ISOTOPOMERS: STRUCTURES AND INTERMOLECULAR VIBRATIONS IN THE $S_{1}$ - STATE
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Date
1997
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Ohio State University
Abstract
Resonant two photon ionization spectra (R2PI) of hydrogen bonded Phenol-water clusters up to 10 $H_{2}O$ were obtained in a supersonic jet expansion with ion detection via a special highly sensitive time of flight mass spectrometer. Using spectral hole burning (SHB) the unusually broad transitions to the intermolecular vibrations of Phenol $(H_{2}O)_{2}$ and Phenol $d_{1} -(D_{2}O)_{2}$ were observed for the first time. For Phenol $(H_{2}O)_{3-5}$ and Phenol-$d_{1}-(D_{2}O)_{3-5}$ the observed intermolecular vibrational frequencies are compared with results from {ab initio} calculations based on cyclic or cage like minimum energy structures for the water moiety. Especially the very low frequencies in the range $10 - 16 cm^{-1}$ which involve mutual ring motion (``butterfly”, twisting, cogwheel movements of the phenol and water rings) turn out to depend quite sensitively on the cluster size and structure. Another ``fingerprint” region are the intermolecular $OH\ldots $O stretch vibrations above $100 cm^{-1}$. SHB is used to clear up the possibility of different isomers for the larger phenol-water clusters.
Description
Author Institution: Institut f\""ur Physikatische Chemie und Elektrochemie, Universit\""at D\""usseldorf