| Project/Area Number |
18K03717
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Review Section |
Basic Section 17010:Space and planetary sciences-related
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| Research Institution | Hokkaido University |
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Principal Investigator |
Tsuge Masashi 北海道大学, 低温科学研究所, 特任助教 (60454211)
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| Project Period (FY) |
2018-04-01 – 2021-03-31
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| Project Status |
Completed (Fiscal Year 2020)
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| Budget Amount *help |
¥4,290,000 (Direct Cost: ¥3,300,000、Indirect Cost: ¥990,000)
Fiscal Year 2020: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000)
Fiscal Year 2019: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000)
Fiscal Year 2018: ¥1,820,000 (Direct Cost: ¥1,400,000、Indirect Cost: ¥420,000)
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| Keywords | 水素原子拡散 / 分子進化 / 氷星間塵 / 星間分子雲 / 星間塵 |
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| Outline of Final Research Achievements |
In the chemical evolution processes occurring within low temperature molecular clouds, it has been demonstrated that chemical reactions on icy grain surface play significant roles. However, chemical processes within ice mantle, which do not require photons and cosmic rays, have not been investigated. In this work, we aimed at revealing whether hydrogen atoms can penetrate into ice mantles or not.
We found that hydrogen atoms penetrate into amorphous solid water and react with embedded atoms or molecules. The most important finding of this work is that hydrogen reactions occur above 20 K, where efficiency of surface hydrogen reactions is extremely low.
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| Academic Significance and Societal Importance of the Research Achievements |
標準的な分子進化モデルにおいては、氷表面と氷内部が異なる相として取り扱われており、水素原子による反応は極低温（<20 K）の表面でのみ起きるとされてきた。しかしながら、本研究で見出した全く新しい反応プロセス「氷内部への水素原子侵入・拡散・反応」は、比較的高い温度（～70 K）でも有効であるとともに、氷表面に吸着する原子種が氷内部における分子生成に影響を与えることを示す。新しい反応プロセスは「光や宇宙線を必要としない氷内部の分子進化プロセス」と言い換えることができ、既存の極低温分子雲における分子進化モデルに大きな変更を要請するという学術的意義を持つ。
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