Temperature Dependence of the Rate Constant for the Reaction HCO + O2 → HO2 + CO at T = 200−398 K
| Autor: | Fred L. Nesbitt, Louis J. Stief, James F. Gleason |
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| Rok vydání: | 1999 |
| Předmět: | |
| Zdroj: | The Journal of Physical Chemistry A. 103:3038-3043 |
| ISSN: | 1520-5215 1089-5639 |
| DOI: | 10.1021/jp984781q |
| Popis: | The absolute rate constant for the reaction HCO + O2 has been measured over the temperature range T = 200−398 K in a discharge flow system at a pressure of 1 Torr (He). This study represents the first measurement of this rate constant at temperatures below T = 298 K. The decay of the HCO radical in the presence of excess O2 was followed by collision-free sampling photoionization mass spectrometry. The results were as follows: k1(200 K) = 5.3 ± 0.8, k1(222 K) = 4.8 ± 0.7, k1(250 K) = 4.4 ± 0.6, k1(298 K) = 4.0 ± 0.6, k1(398 K) = 4.5 ± 0.7 in units 10-12 cm3 molecule-1 s-1. Over the range T = 200−298 K, the data suggest a slight negative temperature dependence and may be represented by the Arrhenius expression k1 = (2.2 ± 0.2) × 10-12 exp[(170 ± 22)/T] cm3 molecule-1 s-1. For the related reaction HCO + NO at T = 298 K we measure k2 = (1.3 ± 0.2) × 10-11 cm3 molecule-1 s-1. The results are compared with previous direct measurements of k1 and k2 and with recent theoretical calculations. For the HCO + O2 reac... |
| Databáze: | OpenAIRE |
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