Table of Contents
Laser Chemistry
Volume 9 (1988), Issue 1-3, Pages 47-62

A Test for Bottlenecks in the Vibrational Relaxation of CH3Cl and CH3Br by Ar

Department of Chemistry, University of Illinois at Chicago, Chicago 60680, Illinois, USA

Received 5 January 1988; Accepted 31 March 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 method of time-resolved optoacoustics was used to measure the rate of vibrational relaxation of CH3Cl(ν6) and CH3Br(ν6) by Ar. The pressure pulses generated by the relaxing gas revealed that the rate of production of translational energy from ν6 = 1 is approximately twice the decay rate of IR fluorescence from ν3 = 1. No evidence was found for a previously proposed bottleneck in rotational relaxation, which would have resulted in an acoustic relaxation rate slower than the fluorescence decay. The faster rates observed here can be explained qualitatively by a rapid energy release from energy levels above ν3 which precedes the IR fluorescence. A simple three-level model, however, is unable to explain our observations quantitatively.