Vibrational spectra and relaxation of benzonitrile and its clusters using time-resolved stimulated Raman-UV double resonance spectroscopy

Citation
R. Yamamoto et al., Vibrational spectra and relaxation of benzonitrile and its clusters using time-resolved stimulated Raman-UV double resonance spectroscopy, J RAMAN SP, 31(4), 2000, pp. 295-304
Citations number
18
Categorie Soggetti
Spectroscopy /Instrumentation/Analytical Sciences
Journal title
JOURNAL OF RAMAN SPECTROSCOPY
ISSN journal
03770486 → ACNP
Volume
31
Issue
4
Year of publication
2000
Pages
295 - 304
Database
ISI
SICI code
0377-0486(200004)31:4<295:VSAROB>2.0.ZU;2-2
Abstract
Raman spectra of ring-breathing (nu(12)) and CN stretching vibrations (nu(C N)) of jet-cooled benzonitrile and its clusters with Ar, H2O, CH3OH, CH3CN, CCl4, CHCl3 and CHF3 were observed by stimulated Raman-UV double resonance spectroscopy. Cluster structures were determined on the basis of the obser ved vibrational spectra, rotational contour analyses of the high resolution S-1-S-0 electronic spectra and ab initio molecular orbital calculations wi th the HF/6-31G(d,p) basis set. It was found that the types of the cluster structures are classified into three groups. (1) The clusters with H2O, CH3 OH and CH3CN represent the 'side'-type structure, in which the intermolecul ar bond is formed in the phenyl plane of benzonitrile, and the benzonitrile dimer also belongs to this structure. (2) The clusters with Ar and CCl4 fo rm the 'on-top'-type structure, where Ar or CCl4 is located above the pheny l plane. (3) The clusters with CHCl3 and CHF3 have the 'linear'-type struct ure, in which these molecules are located at the N end of the CN group of b enzonitrile. The rate constants of the vibrational relaxation for these clu sters occurring after the Raman excitation to their nu(12) vibrations were also observed. It was found that different rate constants are associated wi th the different types of cluster structures. That is, the 12(1) levels of the 'side'-type clusters relax much faster than those of other types of the clusters. The results represent a clear indication that the anharmonic cou pling between nu(12) and intermolecular vibrations are much larger in the ' side'-type clusters than others. Copyright (C) 2000 John Wiley & Sons, Ltd.