Measuring scattering distributions in scanning helium microscopy.

A scanning helium microscope typically utilises a thermal energy helium atom beam, with an energy and wavelength (¡100meV, ∼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.

Standardizing resolution definition in scanning helium microscopy.

Resolution is a key parameter for microscopy, but methods for standardizing its definition are often poorly defined. For a developing technique such as scanning helium microscopy, it is critical that a consensus-based protocol for determining instrument resolution is prepared as a written standard to allow both comparable quantitative measurements of surface topography and direct comparisons between different instruments. In this paper we assess a range of quantitative methods for determining instrument resolution and determine their relative merits when applied to the specific case of the scanning helium microscope (SHeM). Consequently, we present a preliminary protocol for measuring the resolution in scanning helium microscopy based upon utilizing appropriate test samples with sets of slits of well-defined dimensions to establish the quantitative resolution of any similar instrument.