2021 Fiscal Year Annual Research Report
An experimental study of photochemistry for phosphine on interstellar silicate dust
| Project/Area Number |
21K13974
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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) |
2021-04-01 – 2022-03-31
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| Keywords | Astrochemistry / Interstellar medium / Amorphous silicate / Photochemistry / Phosphine |
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| Outline of Annual Research Achievements |
The purpose is to study the photochemistry of phosphine and PH3 containing ices on bare silicate dust at low temperatures (typically 10 K).
Firstly, I carried out experiments on the photochemical reactions of PH3 on amorphous forsterite (Mg2SiO4), which is expected to be dominant components of interstellar grains, at 10K. I obtained the missing PH3 on Mg2SiO4 at 10K by photodissociation after UV photolysis following reactions: PH3 + hv → PH2 + H; simultaneously, a small trace of P2H4 could be formed from PH2 + PH2 → P2H4 reaction. I also carried out another experiment of PH3 photolysis on water ice at 10 K to compare to the effective photodesorption of PH3 on Mg2SiO4. Based on the effective photodesorption of PH3, I may remark that the different effective photodesorption of PH3 on Mg2SiO4 and on water ice is due to the big different binding energy on different surfaces.
Secondly, I surveyed the photolysis of PH3/CO binary on Mg2SiO4. After photodissociation of PH3/CO binary on Mg2SiO4 in 2 hours, I got some products as HCO, H2CO, and HPCO. HCO and H2CO were formed from CO + H reaction; in there, H atoms were produced from the photodissociation of PH3. Furthermore, HPCO, which should be formed from PH + CO → HPCO reaction, has been detected. Additional, HPCO is a phosphorus containing analogues of isocyanic Acid which has been proposed to exit in interstellar space, but it has not been detected there. My experimental result, therefore, may contribute to study the complex phosphorus molecules on bare silicate dust.
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