Spatially resolved lattice characterization using a scanning helium microscope

Abstract

The scanning helium microscope (SHeM) uses low energy helium atoms ($E$ $<$100 meV, $\lambda \sim$0.05 nm) to collect surface sensitive images of samples. Recent work has focused on in-situ measurements of the scattering distribution from a spatially resolved region to determine material properties such as local lattice features through atomic diffraction. To date, these measurements have been restricted to in-plane scans. Here we present instrumentation for the in-situ collection of two dimensional helium scattering distributions in a SHeM. The detection stage was manufactured using UHV compatible 3D printing and then manipulated using in-vacuum stages to measure the distributions. To demonstrate the capabilities of the instrument, several diffraction patterns from a LiF crystal were collected. These diffraction patterns have then been used to both determine the thermal attenuation of the specular peak, as well as a benchmark for comparison to current helium-surface interaction potentials.