Table of Contents
Laser Chemistry
Volume 9 (1988), Issue 4-6, Pages 385-400

Rotational Relaxation of Benzophenone in the Vapour Phase

Department of Chemistry, University of Manchester, Manchester M13 9PL, UK

Received 20 May 1988

Copyright © 1988 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.


The excited singlet state lifetimes of benzophenone vapour have been measured at shorter wavelengths than previous studies and with picosecond time resolution. Excitation was at a series of wavelengths from 313.5 nm to 284 nm, which gave S2(ΠΠ*) decay times of tens of picoseconds. We also report measurements of the polarisation anisotropy decay due to free rotation of excited state benzophenone. Time-dependent anisotropies calculated by both quantum mechanical and classical formulae are in good agreement with the experimental data and demonstrate benzophenone to behave as a rigid rotor. From the residual anisotropy, at long times, it is concluded that no rotation to vibrational energy transfer occurs during the excited state lifetime.