Measuring scattering distributions in scanning helium microscopy

TL;DR

This paper introduces an angular detector stage for scanning helium microscopes, enabling in-situ measurement of scattering distributions to analyze surface structures and topography effects.

Contribution

It presents a novel in-situ angular detector for helium microscopy, allowing detailed analysis of elastic, inelastic, and diffuse scattering from various surfaces.

Findings

Elastic and inelastic scattering from ordered surfaces demonstrated

Diffuse scattering deviations observed on disordered surfaces

Scattering distributions encode detailed surface information

Abstract

A scanning helium microscope typically utilises a thermal energy helium atom beam, with an energy and wavelength (<100 meV, ~0.05 nm) particularly sensitive to surface structure. An angular detector stage for a scanning helium microscope is presented that facilitates the in-situ measurement of scattering distributions from a sample. We begin by demonstrating typical elastic and inelastic scattering from ordered surfaces. We then go on to show the role of topography in diffuse scattering from disordered surfaces, observing deviations from simple cosine scattering. In total, these studies demonstrate the wealth of information that is encoded into the scattering distributions obtained with the technique.