| 研究実績の概要 |
To understand the formation of the complex organic molecules (COM), quantitative mechanistic details of the radical reactions on icy grains at very low temperatures are required. I use quantum chemical calculations to determine quantitative mechanistic details of the radical reactions on the interstellar ices. The present study calculated reaction mechanisms between CH3OH, an important molecule in the interstellar medium (ISM), and an OH radical on ices using the multi-component artificial force induced reaction (MC-AFIR) method. The artificial force of 100 kJ/mol was added between the OH and CH3OH on an ice cluster models. The MC-AFIR search gave a number of reaction paths, where I found two reaction mechanisms; OH + CH3OH -> CH2OH + H2O and OH + CH3OH ->CH3O + H2O. Both reaction mechanisms have very low reaction barriers. Thus, both reactions would occur on ices at low temperatures. Among the products of the reactions, formation of CH2OH is thermodynamically more stable than CH3O formation.
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| 今後の研究の推進方策 |
The next step is to calculate reaction rates for the two mechanisms; OH + CH3OH ->CH2OH + H2O and OH + CH3OH -> CH3O + H2O. The transition state theory, including quantum tunnelling at low temperatures, will be used for this purpose. As the next step, another CH3OH molecule and a H2O molecule will be introduced, i.e., OH + 2CH3OH + H2O. Then the reaction mechanisms on ices will be determined from the MC-AFIR method. Finally, detailed reaction mechanisms for the formation of methyl formate, glycolaldehyde, methoxy methanol, and ethylene glycol will be rationalized.
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