A time-resolved lif study of the kinetics of OH(ν = 0) and OH(ν = 1) with HCl and HBr |
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Authors: | Bret D Cannon John S Robertshaw Ian WM Smith Martin D Williams |
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Institution: | Department of Physical Chemistry, University Chemical Laboratories, Lensfield Road, Cambridge CB2 1EP, UK |
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Abstract: | The kinetics of OH(ν = 0) and OH(ν = 1) have been followed using pulsed photolysis of H2O or HNO3 to generate hydroxyl radicals, and time-resolved, laser-induced fluorescence to observe the rates of their subsequent removal in the presence of HCl or HBr. The experiments yield the following rate constants (cm3 molecule?1 s?1) at 298 ± 4 K: OH(ν = 0) + HCl: ko = (6.8 ± 0.25) × 10?13; OH(ν = 0) + HBr: ko = (11.2 ± 0.45) × 10?12; OH(ν = 1) + HCl: k1 = (9.7 ± 1.0) × 10?13; OH(gn = 1) + HBr; k1 = (8.1 ± 1.05) × 10?12 For OH(ν = 1), the measurements do not distinguish between loss by reaction and relaxation, and the fact that k1 > ko for HCl is tentatively attributed to relaxation, probably by near-resonant vibrational—vibrational energy transfer. Clearly, neither of these exothermic, low-activation-energy reactions is enhanced to any great extent, if at all, by vibrational excitation of the OH radical.ft]*|Present address: Battelle/Pacific Northwest Laboratories, P.O. Box 999, Richland, Washington 99352, USA. |
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