Search for unknown processes on molecular evolution in space: photochemical reactions induced by visible light

2022 Fiscal Year Final Research Report

• Project/Area Number: 21K18639
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 17:Earth and planetary science and related fields
• Research Institution: Hokkaido University
• Principal Investigator: Oba Yasuhiro 北海道大学, 低温科学研究所, 准教授 (00507535)
• Co-Investigator(Kenkyū-buntansha): 新家 寛正 東北大学, 多元物質科学研究所, 助教 (40768983)
• Project Period (FY): 2021-07-09 – 2023-03-31
• Keywords: 光化学反応 / 可視光 / 分子進化 / 局在表面プラズモン共鳴

Outline of Final Research Achievements

Some of organic molecules present in extraterrestrial environments were exposed to photons with the wavelength in the visible light range (532 nm) to better understand possible photochemical reaction caused by visible light with the aid of catalytic materials. When racemic amino acid alanine was exposed to circularly polarized light in the presence of several catalysts for up to 80 hours, their D/L ratio did not clearly change, meaning that visible light has negligible effect on their D/L ratio in extraterrestrial materials. When nitrogen heterocyclic molecules such as HMT, uracil, and nicotinic acid were exposed to visible light at 532 nm, it seems that they are destructed under certain conditions with degradation products. Although further research is necessary to confirm the exact effect of visible light on their degradation, the present study suggests that visible light could have a contribution to molecular distributions in extraterrestrial environments.

Free Research Field

宇宙地球化学

Academic Significance and Societal Importance of the Research Achievements

地球外環境では真空紫外光による光化学反応が分子進化に大きな寄与があると広く受け入れられており，これまでに無数の研究がおこなわれてきた。しかし光のフラックスとしてはそうした真空紫外光領域よりも可視光領域のほうがはるかに高かったが，フォトンエネルギーが化学反応進行に不十分であったため，光化学反応に対する可視光の影響は無視されてきた。しかし本研究で示唆された，触媒存在下での可視光領域での光化学反応はこれまでの認識を覆しうる重要な結果といえる。一方で，可視光の影響の具体的評価にはさらに検証すべき項目が多く残されており，今後の課題といえる。