| Project/Area Number |
17K18795
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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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| Research Field |
Earth and planetary science and related fields
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| Research Institution | Hokkaido University |
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Principal Investigator |
Hama Tetsuya 北海道大学, 低温科学研究所, 助教 (20579172)
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| Project Period (FY) |
2017-06-30 – 2019-03-31
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| Project Status |
Completed (Fiscal Year 2018)
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| Budget Amount *help |
¥6,370,000 (Direct Cost: ¥4,900,000、Indirect Cost: ¥1,470,000)
Fiscal Year 2018: ¥1,820,000 (Direct Cost: ¥1,400,000、Indirect Cost: ¥420,000)
Fiscal Year 2017: ¥4,550,000 (Direct Cost: ¥3,500,000、Indirect Cost: ¥1,050,000)
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| Keywords | 核スピン選択則 / 気相化学反応 / 核スピン異性体 / 星間化学 / 彗星 / 星間分子雲 / 原始惑星系円盤 |
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| Outline of Final Research Achievements |
Observations of interstellar space and cometary comae have reported the existence of gaseous molecules (e.g., H2O) with anomalous ortho-to-para ratios (OPRs) less than the statistical value (three for H2O). However, the true meaning of the observed OPRs in cometary comae and star- and planet-forming regions is still unknown. Gas-phase chemical reactions involving para-H2 should be key to account for the anomalously low ortho-to-para ratios (OPRs) exhibited by interstellar and cometary molecules, because the abundance ratio of nuclear spin isomers of the product molecules (e.g., H2O) can be para-enriched owing to the nuclear-spin selection rules. In this work, a new experimetal apparatus is designed and constructed for the understanding of the nuclear-spin selection rules of gas-phase chemical reactions involving para-H2.
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| Academic Significance and Societal Importance of the Research Achievements |
天文学や地球惑星科学では「星間分子（H2O, NH3, CH4など）の核スピン異性体比から，分子が過去にどのような環境で生成したのかがわかる」と考えられており，積極的に観測研究が進められてきた．しかし，近年の代表者の実験研究によって「H2Oの核スピン異性体比からはH2O氷の生成時の環境を知ることができない」ことが明らかになったため，星間分子の核スピン異性体比が本当は何を意味しているのかは，30年以上の観測研究の蓄積にも関わらず未だに不明である．本研究によって「星間分子の核スピン異性体比が異常な値をもつのは，気相化学反応が原因である」という新説を提案・検証するための基礎が確立した．
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