Probing the NO2→NO+O transition state via time resolved unimolecular decomposition
| Autor: | Curt Wittig, Y. Chen, C. Jaques, G. A. Brucker, S. I. Ionov |
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| Rok vydání: | 1993 |
| Předmět: | |
| Zdroj: | The Journal of Chemical Physics. 99:3420-3435 |
| ISSN: | 1089-7690 0021-9606 |
| Popis: | Time resolved, subpicosecond resolution measurements of photoinitiated NO2 unimolecular decomposition rates are reported for expansion cooled and room temperature samples. The molecules are excited by 375–402 nm tunable subpicosecond pulses having bandwidths ≥20 cm−1 to levels which are known to be thorough admixtures of the 2B2 electronically excited state and the 2A1 ground electronic state. Subsequent decomposition is probed by a 226 nm subpicosecond pulse that excites laser‐induced fluorescence (LIF) in the NO product. When increasing the amount of excitation over the dissociation threshold, an uneven, ‘‘step‐like’’ increase of the decomposition rate vs energy is observed for expansion cooled samples. The steps are spaced by ∼100 cm−1 and can be assigned ad hoc to bending at the transition state. Relying on experimental estimates for the near threshold density of states, we point out that simple transition state theory predictions give rates that are consistent with these measured values. The rates ar... |
| Databáze: | OpenAIRE |
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