Measurements of the HF vibration-vibration transfer time and apparent vibration decay rate of using observation of the v = 2 v = 1 fluorescence in HF

An experiment resulting in measurement of vibration to vibration transfer rate in pure HF is described. The technique involves pumping a sample cell containing pure HF with an HF chemical laser oscillating on a transition, and then using a filter cell monoehromator combination to separate the fluorescence from that of . An analytic model yielding the time resolved fluorescence is also developed. This model indicates that the rise time of the observed fluorescence gives a direct measurement of the vibration-vibration transfer rate, out of ; that is, the process HF( ) + HF HF( ). In addition it shows that the population of is proportional to its rate of production and hence to the population in the state squared. As a result the apparent decay rate of our observed fluorescence is twice that for . We find good agreement between these predictions and the results of the time resolved fluorescence experiments. The implication of these results to previous measurements of HF V-T (or V-R) relaxation rate is discussed briefly.