Temperature dependence in fast-atom diffraction at surfaces

TL;DR

This study investigates how surface temperature affects fast-atom diffraction patterns at LiF surfaces, revealing that coherence loss is mainly due to surface stiffness and defects rather than attraction forces, with implications for surface analysis.

Contribution

First extensive evaluation of temperature effects on fast-atom diffraction at LiF surfaces, highlighting the roles of surface stiffness and defects in coherence loss.

Findings

Elastic intensity decreases exponentially with temperature.

Surface defects significantly impact diffraction coherence.

Attraction forces have minimal effect on maximum coherence.

Abstract

Grazing incidence fast atom diffraction at crystal surfaces (GIFAD or FAD) has demonstrated coherent diffraction both at effective energies close to one eV ($\lambda_\perp\approx$ 14 pm for He) and at elevated surface temperatures offering high topological resolution and real time monitoring of growth processes. This is explained by a favorable Debye-Waller factor specific to the multiple collision regime of grazing incidence. This paper presents the first extensive evaluation of the temperature behavior between 177 and 1017 K on a LiF surface. Similarly to diffraction at thermal energies, an exponential attenuation of the elastic intensity is observed but the maximum coherence is hardly limited by the attraction forces. It is more influenced by the surface stiffness and appears very sensitive to surface defects.