# Experimental evidence for Glycolaldehyde and Ethylene Glycol formation by surface hydrogenation of CO molecules under dense molecular cloud conditions

## TL;DR

This paper provides experimental evidence that glycolaldehyde and ethylene glycol can form through surface hydrogenation of CO molecules in dense molecular clouds, with implications for astrochemical models.

## Contribution

It demonstrates experimentally that complex molecules like glycolaldehyde and ethylene glycol form via CO hydrogenation, and integrates these pathways into astrochemical models.

## Key findings

- Formation of glycolaldehyde and ethylene glycol confirmed experimentally.
- Reaction pathways involving HCO radical recombination established.
- Model predicts significant abundances of these molecules in dense clouds.

## Abstract

This study focuses on the formation of two molecules of astrobiological importance - glycolaldehyde (HC(O)CH2OH) and ethylene glycol (H2C(OH)CH2OH) - by surface hydrogenation of CO molecules. Our experiments aim at simulating the CO freeze-out stage in interstellar dark cloud regions, well before thermal and energetic processing become dominant. It is shown that along with the formation of H2CO and CH3OH - two well established products of CO hydrogenation - also molecules with more than one carbon atom form. The key step in this process is believed to be the recombination of two HCO radicals followed by the formation of a C-C bond. The experimentally established reaction pathways are implemented into a continuous-time random-walk Monte Carlo model, previously used to model the formation of CH3OH on astrochemical time-scales, to study their impact on the solid-state abundances in dense interstellar clouds of glycolaldehyde and ethylene glycol.

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Source: https://tomesphere.com/paper/1705.09235