Formation of hydroxylamine on dust grains via ammonia oxidation

TL;DR

This study investigates how hydroxylamine, a potential precursor to amino acids, can form on dust grains in space through ammonia oxidation, combining laboratory experiments and simulations to predict its abundance in dense clouds.

Contribution

It provides the first experimental evidence and simulation-based predictions of hydroxylamine formation on dust grains via ammonia oxidation in space.

Findings

Hydroxylamine forms on dust grains at 14 K with significant abundance.

The formation process has a modest activation energy barrier.

Predicted hydroxylamine abundance is at least 10% of ammonia in dense clouds.

Abstract

The quest to detect prebiotic molecules in space, notably amino acids, requires an understanding of the chemistry involving nitrogen atoms. Hydroxylamine (NH$_2$OH) is considered a precursor to the amino acid glycine. Although not yet detected, NH$_2$OH is considered a likely target of detection with ALMA. We report on an experimental investigation of the formation of hydroxylamine on an amorphous silicate surface via the oxidation of ammonia. The experimental data are then fed into a simulation of the formation of NH$_2$OH in dense cloud conditions. On ices at 14 K and with a modest activation energy barrier, NH$_2$OH is found to be formed with an abundance that never falls below a factor 10 with respect to NH$_3$. Suggestions of conditions for future observations are provided.