REACTION AND DEACTIVATION OF HCl (v = 1, 2) BY Cl, Br, AND H ATOMS

Journal Article · Fri Feb 01 04:00:00 EST 1980 · Journal of Chemical Physics

DOI:https://doi.org/10.1063/1.440350· OSTI ID:1064019

Macdonald, R G; Moore, C Bradley

Total decay rates for HCl(v = 2, 1) were measured in the range 294 - 439 K for Cl, 295 - 390 K for Br, and at 296 K for H. HCl(v = 2) was produced directly by pulsed laser excitation of the overtone. The fraction of HCl(v = 2) relaxed to HCl(v = 1) was determined. For HCl(v = 2) + Cl, relaxation gave entirely HCl(v = 1) within an experimental uncertainty of ± 10%, the total relaxation rate was large, k/v = 5 {Angstrom}{sup 2} , and rates varied only slightly with temperature. For Br + HCl(v = 2) reaction to HBr(v = 0) + Cl is exoergic by about kT. Relaxation to HCl(v = 1) is the dominant process. Reaction contributes roughly 17% and 34% to the loss of HCl(v = 2) at 295 and 390 K, respectively. In constrast to the result for Br and for O (reported previously) H + HCl(v = 2) gives 65% H{sub 2} + Cl and only 35% HCl(v = 1) +H. For HCl(v = 1) + H Cl, O the vibrational excitation energy is greater than the activation energy for reaction. The relaxation rates are between 1/2 and 1/3 of the A values for the measured thermal exchange rates Aexp(-{Delta}E{sub act}/RT). For HCl(v = 1) + Br, well below threshold, the rate is some 20 times less than for HCl(v = 1) + Cl. The rate for HCl(v = 2) + Br, just above reaction threshold is not dramatically larger. The ratios of vibrational relaxation rates for HCl(v = 2) vs HCl(v = 1) are 5.0 ± 1.3, 4.2 ± 0.4, and 5.0 ± 1.3 for O, Cl, and Br, respectively. Any first order linear perturbation treatment gives rates proportional to v; the data scale more closely as v{sup 2}.

• Research Organization: Ernest Orlando Lawrence Berkeley National Laboratory, Berkeley, CA (US)
• Sponsoring Organization: Materials Sciences Division
• DOE Contract Number: AC02-05CH11231
• OSTI ID: 1064019
• Report Number(s): LBL-10582
• Journal Information: Journal of Chemical Physics, Journal Name: Journal of Chemical Physics Journal Issue: 4 Vol. 73; ISSN 0021-9606
• Country of Publication: United States
• Language: English

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