Decay Dynamics of H Atoms in Solid Hydrogen at 4.2 K. Controlling Factor of Tunneling Reaction H + para-H2 → para-H2 + H
| Autor: | Toshimitsu Nagasaka, Tetsuo Miyazaki, Shoji Mori, Jun Kumagai, Yasuyuki Aratono, Takayuki Kumada |
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| Rok vydání: | 2000 |
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| Zdroj: | The Journal of Physical Chemistry A. 104:9403-9407 |
| ISSN: | 1520-5215 1089-5639 |
| DOI: | 10.1021/jp000440c |
| Popis: | H atoms produced by the γ-ray irradiation of solid para-H2 (p-H2) and solid normal-H2 (n-H2) decay gradually when the irradiated sample is stored at 4.2 K. ortho-H2 (o-H2) molecules at the sites nearest an H atom in solid n-H2 convert to p-H2 molecules by interacting with the H atom. H atoms in solid H2 decay by the process of tunneling diffusion H + p-H2 → p-H2 + H and finally recombine with other H atoms. The rate constants for the tunneling reaction were obtained from the decay rates of H atoms in solid H2 at various concentrations of o-H2. When solid n-H2 is stored for 10 h at 4.2 K after γ-ray irradiation, a number of o-H2 molecules change into p-H2 molecules by a catalytic chain reaction induced by mobile H atoms. The G value of the o-H2 yields from H atoms amounts to 1−2.6 × 104. The rate constant for the tunneling reaction H + p-H2 → p-H2 + H decreases drastically with increasing numbers of o-H2 molecules, which exist as orientational defects in solid p-H2. It was concluded that a very small amoun... |
| Databáze: | OpenAIRE |
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