Elucidation of ion-surface reactions on a interstellar dust surface: exploring their unknown roles in molecular evolution

2021 Fiscal Year Final Research Report

• Project/Area Number: 18H01273
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 17010:Space and planetary sciences-related
• Research Institution: Institute of Physical and Chemical Research
• Principal Investigator: Nakai Yoichi 国立研究開発法人理化学研究所, 仁科加速器科学研究センター, 専任研究員 (30260194)
• Co-Investigator(Kenkyū-buntansha): 日高 宏 北海道大学, 低温科学研究所, 助教 (00400010)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: イオン表面反応 / 星間化学過程

Outline of Final Research Achievements

We have performed experimental studies of the reactions between low-energy molecular ions and the surface of interstellar dust ice, for which there was little experimental information. For this purpose, we have developed an experimental apparatus using a reactive scattered ion mass spectrometry (RIS), which is more sensitive than the conventional detection methods for chemical species existing on the surface. The method was improved so that the advantage of RIS could be utilized for chemical species on the low-temperature ice surface. As a result, we have achieved high detection sensitivity for chemical species on low-temperature ice surface. The reaction products were observed after irradiating the surface of the ice thin film formed on the cooled metal substrate with low-energy CH3+ ions. We obtained experimental results indicating the formation of methanol molecules due to the irradiation of the CH3+ ions to the ice surface.

Free Research Field

原子分子科学，宇宙化学

Academic Significance and Societal Importance of the Research Achievements

本研究での実験結果は，低エネルギーのイオンと極低温氷表面との分子生成反応実験として，我々の知る限り，世界で初めて得られた結果である．これは以前の理論的予測を支持するものとなった．実験的情報の不足もあり，低エネルギーのイオンと氷表面との反応による分子生成は，これまでの星間雲での分子生成のモデルでは取り入れられてこなかった．しかし，今後その重要性を適切に評価する必要が出てくるだろう．また，極低温氷表面上の化学種の高感度検出法として，反応性散乱イオン質量分析法が有用であることが示された．