Abstract
RECENT interest in chemical lasers has been strongly directed towards systems which give rise to vibrationally excited hydrogen halide molecules1–7. The efficiency of such systems will clearly depend on the rate at which vibrational energy is removed from the products of the chemical reaction, and considerable effort has been made to obtain the relevant rate data. Airey8 has described a pulsed laser system based on the reaction9,10 and has discussed the various energy transfer processes which may be involved. Moore et al. and Airey (see ref. 11) have further used reaction (1) to obtain rate data for the process. We have independently undertaken an extensive study of energy transfer processes involving the hydrogen bromide molecule using rather different techniques to monitor the vibrationally excited species and wish to report here rate data for the vibrational relaxation of HBr(ν″ = 1) by HCl. In our system, vibrationally excited HBr is produced by the fast reaction9,10 following the flash photolysis of HBr (pHBr = 33.3 Nm−2) in the presence of Br2 ( = 4.1 Nm−2), and excess Ar (pAr = 13.3 k Nm−2) to prevent a significant rise above room temperature (T = 300 K). Near resonant exchange processes rapidly reduced the initial vibrational distribution in HBr to a condition where a non-Boltzmann distribution in HBr(ν″ = 1) is observed. Relaxation from this level to ν″ = 0 can then be conveniently monitored, using kinetic absorption spectroscopy in the vacuum ultraviolet12, to observe the (0,1) transition of the strongly predissociated system connecting the ground state with “state [6]” (ν0 = 70,526 cm−1) (refs. 13, 14).
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DONOVAN, R., HUSAIN, D. & STEVENSON, C. Vibrational Relaxation of HBr(ν″ = 1) by HCl at 300 K. Nature 227, 602–603 (1970). https://doi.org/10.1038/227602a0
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DOI: https://doi.org/10.1038/227602a0
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