2020 Fiscal Year Annual Research Report
Experimental study on photochemistry of water and CO molecules on silicate dust
| Project/Area Number |
19K23449
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| Research Institution | Hokkaido University |
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Principal Investigator |
NGUYEN THANH 北海道大学, 低温科学研究所, 博士研究員 (40846599)
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| Project Period (FY) |
2019-08-30 – 2021-03-31
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| Keywords | Molecular clouds / Astrochemistry |
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| Outline of Annual Research Achievements |
I have experimentally studied the chemical desorption and physico-chemical behavior of phosphine molecules, which is one of curial molecules of phosphorus (P)-bearing species in molecular clouds.
I have completed the study involving the physico-chemical behavior of PH3 by the H-D substitution reaction in dust grains (Nguyen et al. submitted to ApJ (2021)). I found that phosphine and its deuterated isotopologue PD3 are released into the gas phase from icy surfaces via chemical desorption. Since the activation barriers for the abstraction of H or D atoms is 1500 K, quantum tunneling should play a role at low temperatures. Under the present experimental conditions, the H-D substitution reactions of PH3 is slightly lower than the D-H substitution reactions of PD3. Therefore, the rates of the substitution reactions should not be constrained by quantum tunneling but rather by other elementary processes such as atom diffusion on ice. In addition, the experimental results suggest the possible presence of deuterated phosphine isotopologue (PH2D) in PH3-rich interstellar environments.
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