H-atom-assisted formation of key radical intermediates in interstellar sugar synthesis

New insights from para-H₂ matrix isolation experiments

¹ Laboratory of Molecular Spectroscopy, Institute of Chemistry, ELTE Eötvös Loránd University, PO Box 32, 1518 Budapest, Hungary
e-mail: gyorgy.tarczay@ttk.elte.hu
² Hevesy György PhD School of Chemistry, Institute of Chemistry, ELTE Eötvös Loránd University, PO Box 32, 1518 Budapest, Hungary
³ Laboratory of Theoretical Chemistry, Institute of Chemistry, ELTE Eötvös Loránd University, 1117, Budapest, Hungary
e-mail: szalay@chem.elte.hu
⁴ MTA-ELTE Lendület Laboratory Astrochemistry Research Group, Institute of Chemistry, ELTE Eötvös Loránd University, PO Box 32, 1518 Budapest, Hungary
⁵ Present address: School of Advanced Sciences (SAS), Vellore Institute of Technology, Vellore Campus, Vellore 632014, Tamil Nadu, India
⁶ Centre for Astrophysics and Space Science, ELTE Eötvös Loránd University, PO Box 32, 1518 Budapest, Hungary

Received: 8 May 2024
Accepted: 18 June 2024

Abstract

Context. Despite the identification of the smallest sugar molecule, glycolaldehyde (GA), in the interstellar medium (ISM), its mechanism of formation in the ISM is still not fully understood. A more profound understanding of the interstellar chemistry of GA and related molecules could provide insights into whether larger sugar molecules can also form and survive under such conditions.

Aims. The primary objectives of this research are to delve into the sugar formation mechanism in the ISM, especially in dark molecular clouds; unravel intricate details of H-atom-mediated reactions involving glyoxal (GO), GA, and ethylene glycol (EG); and identify intermediates playing potential roles in the formation of larger sugars or serving as intermediates in the destruction reaction paths of sugar molecules.

Methods. The study utilizes the para-H₂ matrix isolation method with infrared (IR) spectroscopic detection and quantum chemical computations to investigate H-atom reactions of GO, GA, and EG at a low temperature.

Results. Several radical products were spectroscopically identified that might be key active species in the interstellar formation of larger sugar molecules.