Experimental study on photochemistry of water and CO molecules on silicate dust

2020 Fiscal Year Final Research Report

• Project/Area Number: 19K23449
• Research Category: Grant-in-Aid for Research Activity Start-up
• Allocation Type: Multi-year Fund
• Review Section: 0204:Astronomy, earth and planetary science, and related fields
• Research Institution: Hokkaido University
• Principal Investigator: NGUYEN THANH 北海道大学, 低温科学研究所, 博士研究員 (40846599)
• Project Period (FY): 2019-08-30 – 2021-03-31
• Keywords: Astrochemistry / Molecular clouds / Photochemistry

Outline of Final Research Achievements

Chemical processes of molecules on cosmic ice dust play a significant role for chemical evolution in dense molecular clouds. In contrast, it remains totally unknown how molecules evolve on bare cosmic dust where ice mantles are not formed yet. The present study is to investigate the formation of primitive molecules on silicate dust analogs in dense clouds. In particular, the study is focusing on the photolysis of water and photochemical reactions of H2O/CO on amorphous silicate at 10 K. We confirmed that a small amount of water was lost from the amorphous silicate surface due to destruction by UV photons at 10 K. Additionally, the photochemical reaction of water/CO binary was not effective on amorphous silicate at 10 K.
Another study involving the chemistry of phosphine (PH3) on amorphous indicated that PH3 was lost from the surface due to chemical desorption via exposure to H atoms. The present study will contribute to better understand the initial stage of chemical evolution in MCs.

Free Research Field

Astrochemistry

Academic Significance and Societal Importance of the Research Achievements

These results contribute to the development of the astrochemistry field. Chemical evolution on bare cosmic dust is still an open question that scientists are always concerned about in the world. So, the present results can give one of the explanations for chemical processes on bare cosmic dust.