# Synthesis of solid-state Complex Organic Molecules through accretion of simple species at low temperatures

## TL;DR

This study demonstrates that complex organic molecules like propanal and 1-propanol can form on icy grains at 10 K through non-energetic processes, with implications for astrochemistry and astrobiology.

## Contribution

It provides experimental evidence for solid-state formation of COMs at low temperatures, including molecules not yet detected in space, supported by astronomical observations and computational analysis.

## Key findings

- Propanal forms at 10 K in laboratory simulations.
- 1-Propanol is produced from propanal in experiments.
- Astronomical observations set upper limits on 1-propanol abundance.

## Abstract

Complex organic molecules (COMs) have been detected in the gas-phase in cold and lightless molecular cores. Recent solid-state laboratory experiments have provided strong evidence that COMs can be formed on icy grains through 'non-energetic' processes. In this contribution, we show that propanal and 1-propanol can be formed in this way at the low temperature of 10 K. Propanal has already been detected in space. 1-propanol is an astrobiologically relevant molecule, as it is a primary alcohol, and has not been astronomically detected. Propanal is the major product formed in the C2H2 + CO + H experiment, and 1-propanol is detected in the subsequent propanal + H experiment. The results are published in Qasim et al. (2019c). ALMA observations towards IRAS 16293-2422B are discussed and provide a 1-propanol:propanal upper limit of < 0.35 - 0.55, which are complemented by computationally-derived activation barriers in addition to the performed laboratory experiments.