Detection of the adsorption of water monolayers through the ion oscillation frequency in the magnesium oxide lattice by means of Low Energy Electron Diffraction

TL;DR

This study introduces a novel method using Low Energy Electron Diffraction to detect water monolayer adsorption on magnesium oxide by observing changes in ion oscillation frequencies and surface Debye temperature.

Contribution

The paper presents a new technique to measure adsorbate vibrations on surfaces by analyzing ion oscillation frequency shifts in MgO due to water monolayers.

Findings

Ion oscillation frequencies vary with water monolayer adsorption.

Surface Debye temperature changes correlate with water adsorption/desorption.

Method enables detection of surface chemical shifts caused by adsorbates.

Abstract

We investigate the variation of the oscillation frequency of the Mg$^{2+}$ and O$^{2-}$ ions in the magnesium oxide lattice due to the interactions of the surface with water monolayers by means of Low Energy Electron Diffraction. Our key result is a new technique to determine the adsorbate vibrations produced by the water monolayers on the surface lattice as a consequence of their change in the surface Debye temperature and its chemical shift. The latter was systematically investigated for different annealing times and for a constant external thermal perturbation in the range of 110-300 K in order to accomplish adsorption or desorption of water monolayers in the surface lattice.