Observation of diffuse scattering in scanning helium microscopy

In understanding the nature of contrast in the emerging field of neutral helium microscopy, it is important to identify if there is an atom-surface scattering distribution that can be expected to apply broadly across a range of sample surfaces. Here we present results acquired in a scanning helium m...

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Bibliographic Details
Published in:Physical chemistry chemical physics : PCCP 2022-11, Vol.24 (43), p.26539-26546
Main Authors: Lambrick, S. M, Bergin, M, Ward, D. J, Barr, M, Fahy, A, Myles, T, Radi, A, Dastoor, P. C, Ellis, J, Jardine, A. P
Format: Article
Language:English
Subjects:
Helium atoms
Image contrast
Microscopy
Scattering
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Summary:In understanding the nature of contrast in the emerging field of neutral helium microscopy, it is important to identify if there is an atom-surface scattering distribution that can be expected to apply broadly across a range of sample surfaces. Here we present results acquired in a scanning helium microscope (SHeM) under typical operating conditions, from a range of surfaces in their native state, i.e. without any specialist sample preparation. We observe diffuse scattering, with an approximately cosine distribution centred about the surface normal. The 'cosine-like' distribution is markedly different from those distributions observed from the well-prepared, atomically pristine, surfaces typically studied in helium atom scattering experiments. Knowledge of the typical scattering distribution in SHeM experiments provides a starting basis for interpretation of topographic contrast in images, as well as a reference against which more exotic contrast mechanisms can be compared. By studying well defined geometries (microspheres) in scanning helium microscopy (SHeM) the default scattering distribution for technological surfaces in SHeM is found to be diffuse and approximately cosine.
ISSN:1463-9076
1463-9084
DOI:10.1039/d2cp01951e