2021 Fiscal Year Final Research Report
Formation of hydrous silicate by photochemical reaction between ice and amorphous silicate at low temperatures
| Project/Area Number |
19K21887
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| Research Category |
Grant-in-Aid for Challenging Research (Exploratory)
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| Allocation Type | Multi-year Fund |
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| Review Section |
Medium-sized Section 17:Earth and planetary science and related fields
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| Research Institution | Hokkaido University |
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Principal Investigator |
Kouchi Akira 北海道大学, 低温科学研究所, 教授 (60161866)
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| Project Period (FY) |
2019-06-28 – 2022-03-31
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| Keywords | 非晶質珪酸塩 / 含水鉱物 / 氷 / 紫外線 / 低温 / 光化学反応 / 結晶化 |
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| Outline of Final Research Achievements |
To understand the formation mechanism of OH-bearing silicate at low temperatures, UV-irradiation experiments onto amorphous ice-covered amorphous silicate using a cryogenic transmission electron microscope. Three kind of amorphous silicate fine particles (Mg2SiO4, MgSiO3, and GEMS composition) were made by thermal plasma method. The formation of crystals was observed only when Mg2SiO4 particles were used at 82 K. None of formation was observed when MgSiO3 and GEMS particles were used. Crystals formed from amorphous Mg2SiO4 particles was identified using another high-resolution transmission electron microscope to be forsterite. It has been suggested that OH radicals formed by the photolysis of water molecules plays an essential role on the formation of forsterite.
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| Free Research Field |
地球惑星科学
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| Academic Significance and Societal Importance of the Research Achievements |
原始惑星系における含水鉱物の生成は，地球型惑星の水の起源と関連するので，大変重要な課題である．これまでは非晶質珪酸塩と水蒸気の反応によって高温で含水鉱物が生成されると考えられてきた．今回の研究では，氷に紫外線を照射して生成されるOHラジカルによって，82Kという低温にもかかわらず非晶質珪酸塩が結晶化することが見出された．このことはOHラジカルと非晶質珪酸塩が反応して低温でも含水鉱物が生成される可能性があることを示したもので，今後の研究の展開に大きな期待を持たせる成果である．
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