Table of Contents
Laser Chemistry
Volume 19, Issue 1-4, Pages 75-78
http://dx.doi.org/10.1155/1999/10475

Pump- And Probe-Wavelength Dependencies of Picosecond Anti-Stokes Raman Spectrum of Trans-Stilbene in the S1 State

1Department of Chemistry and Research Centre of Spectrochemistry, School of Science, The University of Tokyo, Bunkyo-ku, Tokyo 113, Japan
2Department of Chemistry, Faculty of Science, Saitama University, Saitama 338, Urawa, Japan

Received 6 April 1997

Copyright © 1999 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Vibrational relaxation dynamics of trans-stilbene in the S1 state immediately after photoexcitation is studied by picosecond time-resolved anti-Stokes Raman spectroscopy with several pump and probe wavelengths. Pump-wavelength dependence of the anti- Stokes spectrum indicates that, when pump photons with high excess energy (≈5200cm-1) are used, the anti-Stokes Raman bands at 0 ps delay time arise from vibrationally excited transients with excess vibrational energy not thermally distributed in the molecule. Probe-wavelength dependence suggests that the vibrationally excited transients at 0 ps are mostly on the lowest excited vibrational levels, as far as the olefinic C═C stretching and the C–Ph stretching modes are concerned. The vibrational relaxation process of S1trans-stilbene is discussed on the basis of the observed results.