Gas temperature dependent sticking of hydrogen on cold amorphous water ice surfaces of interstellar interest

TL;DR

This study investigates how the temperature of hydrogen molecules affects their sticking probability on cold amorphous water ice surfaces, providing a model that explains experimental discrepancies and aids astrophysical modeling.

Contribution

The paper introduces a statistical model explaining isotopic and temperature effects on hydrogen sticking, reconciling previous experimental inconsistencies and fitting theoretical results.

Findings

Sticking probability depends on gas and surface temperatures.

A new analytical formula for sticking coefficients is provided.

The model explains isotopic effects observed in experiments.

Abstract

Using the King & Wells method, we present experimental data on the dependence of the sticking of molecular hydrogen and deuterium on the beam temperature onto non- porous amorphous solid water (ASW) ice surfaces of interstellar interest. A statistical model that explains the isotopic effect and the beam temperature behavior of our data is proposed. This model gives an understanding of the discrepancy between all known experimental results on the sticking of molecular hydrogen. Moreover it is able to fit the theoretical results of V. Buch et al. [Astrophys. J. (1991), 379, 647] on atomic hydrogen and deuterium. For astrophysical applications, an analytical formula for the sticking coefficients of H, D, H2, D2 and HD in the case of a gas phase at thermal equilibrium is also provided at the end of the article.