STIMULATED EMISSION PUMPING MEASUREMENTS OF $I_{2}$(X) ENERGY TRANSFER RATE $CONSTANT^{*}$
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Date
1992
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Ohio State University
Abstract
Highly excited vibrational levels of $I_{2}$(X) are thought to play an important role in the mechanism of the chemical oxygen iodine Iaser (COIL). It has been proposed that $I_{2}$ is dissociated in the laser by processes such $as: ^{*}$ Work performed at the Phillips Laboratory, Kirtland AFB, NM 87117. $I_{2}(X, v^{\prime} = 0) +M^{*} \rightarrow I_{2}(X, v^{\prime} > 20) + M$ $I_{2} (X, v^{\prime} > 20) +M^{*}\rightarrow 21 + M$ Where $M^{*}$ is $O_{2}$ (a) or $I^{2})P_{1/2}$, and M is $O_{2}$ (X) or $I^{2})P_{3/2.}$, Near-resonant E-V transfer in the first step would populate vibrational levels around $v^{\prime} = 40$. Consequently, the relaxation dynamics of these levels are of interests as they may control the efficiency of the laser. In the present work we have used stimulated emission pumping with LIF to study rotational and vibrational relaxation of $I_{2}$ (X, $v^{\prime} = 42$). Population was transferred to this level via the sequence $I_{2} (X, v^{\prime} = 0, J^{\prime} = 15)\rightarrow I_{2} (B, v^{\prime} = 43, J^{\prime} = 16) \rightarrow I_{2} (X, v^{\prime} = 42, J^{\prime} = 17$). The prepared level, and collisionally populated levels, were detected by laser excitation of the D. X system. The relaxation kinetics were determined by variation of the delay between the dump and probe laser pulses. Collisions with He, Ar, $I_{2}$ $O_{2}$, and $N_{2}$ were investigated. Rotational energy transfer rate constants were measured for all collision parmeters. Vibratioinal energy transfer ($\Delta v = - 1$) was observed for He, $O_{2}$, and $N_{2}$, but this process was immeasurably slow for Ar and $I_{2}$. Experimental details, energy transfer rate constants, and the implications of these results with respect of COIL will be presented.""
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Author Institution: Department of Chemistry, Emory University