# Adhesion Properties of Hydrogen on Sb(111) Probed by Helium Atom Scattering

## TL;DR

This study investigates hydrogen adsorption on Sb(111) surfaces using helium atom scattering, revealing temperature-dependent phases, desorption energy, and scattering properties of hydrogen layers.

## Contribution

It provides new insights into the adsorption behavior, phase formation, and desorption characteristics of hydrogen on Sb(111) surfaces through helium atom scattering measurements.

## Key findings

- Hydrogen does not adsorb above 110 K as molecules, but atomic hydrogen forms different phases depending on temperature.
- Ordered hydrogen layers form at room temperature, while low-temperature layers become ordered upon heating.
- Hydrogen desorbs at 430 K with an energy of 1.33 eV, and the initial sticking coefficient decreases with temperature.

## Abstract

We have carried out a series of helium atom scattering measurements in order to characterise the adsorption properties of hydrogen on antimony(111). Molecular hydrogen does not adsorb at temperatures above 110 K in contrast to pre-dissociated atomic hydrogen. Depending on the substrate temperature, two different adlayer phases of atomic hydrogen on Sb(111) occur. At low substrate temperatures ($110~$K), the deposited hydrogen layer does not show any ordering while we observe a perfectly ordered $(1\times 1)$ H/Sb(111) structure for deposition at room temperature. Furthermore, the amorphous hydrogen layer deposited at low temperature forms an ordered overlayer upon heating the crystal to room temperature. Hydrogen starts to desorb at $T_m = 430~$K which corresponds to a desorption energy of $E_{des}=(1.33\pm0.06)~$eV. Using measurements of the helium reflectivity during hydrogen exposure at different surface temperatures, we conclude that the initial sticking coefficient of atomic hydrogen on Sb(111) decreases with increasing surface temperature. Furthermore, the scattering cross section for the diffuse scattering of helium from hydrogen on Sb(111) is determined as $\Sigma = (12 \pm 1)~\mbox{\AA}^{2}$.