Use of direct overtone excitation in the measurement of the HF(v=2) deactivation rate

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Abstract
This letter reports the demonstration of direct optical overtone excitation of the second vibrational level of hydrogen fluoride. A unique variation of the laser‐excited‐fluorescence technique was employed in the experiment to achieve a significant nonequilibrium population of HF(v=2) within a room‐temperature mixture of HF and argon. The HF(v=2) level was excited by a pulse from a temperature‐tuned Nd:YAlO3 laser, and the resultant fluorescence was monitored. The Δv=1 fluorescence from the mixture revealed the presence of a double exponential decay. The preliminary data allow the interpretation of the two exponentials as representing the v=2→v=1 and v=1→v=0 collisional deactivations. This in turn has led to an approximate value for the ratio of the time constants of the processes of τ1/τ2=2.2±0.4.