Probing Surfaces with Thermal He Atoms: Scattering and Microscopy with a Soft Touch

Holst, Bodil; Bracco, G.

doi:10.1007/978-3-642-34243-1_12

Cited by 17 publications

(17 citation statements)

References 236 publications

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“…Several other contrast mechanisms have been found in the images, as predicted by results from the HAS research community [1]. Given the lack of helium beam absorption, contrast must result from changes in the distribution of scattered particles.…”

Section: Nam Imagesmentioning

confidence: 76%

“…Nonetheless, due to the high particle mass, the deBroglie wavelength is under 1Å and therefore near Scanning Electron Microscope (SEM) resolution is theoretically possible. NAM is also termed Scanning Helium [Atom] Microscopy (SHeM or SHeAM) when helium is the beam gas [1]. Molecular beam experiments such as Helium Atom Scattering (HAS) have produced a wealth of information about surface physics and structures, and show that an atom or molecule beam in the energy range from a few meV to the room temperature source energy of 65 meV, or more, should produce contrast mechanisms with a great deal of potential for imaging [1].…”

Section: Introductionmentioning

confidence: 99%

“…NAM is also termed Scanning Helium [Atom] Microscopy (SHeM or SHeAM) when helium is the beam gas [1]. Molecular beam experiments such as Helium Atom Scattering (HAS) have produced a wealth of information about surface physics and structures, and show that an atom or molecule beam in the energy range from a few meV to the room temperature source energy of 65 meV, or more, should produce contrast mechanisms with a great deal of potential for imaging [1]. The lack of charge and low energy make the technique of interest to the semiconductor industry, which must use some materials which are rapidly modified by SEM beams [2].…”

Section: Introductionmentioning

confidence: 99%

“…Two beam forming techniques have succeeded, namely focusing by a Fresnel zone plate in transmission mode [3], and the "pinhole" configuration in reflection mode [4,5]. Summaries of previous work on beam focusing and potential imaging contrast mechanisms are found in [1,4]. This paper discusses recent results from the pinhole NAM, which has produced the only images published to date by the "reflection" of neutral atoms from a sample and currently holds the resolution record (315 nm).…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Exploring neutral atom microscopy

Witham

Sánchez

2014

Crystal Research and Technology

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A new imaging method known as Neutral Atom Microscopy (NAM) or Scanning Helium Microscopy promises to open a unique window to the nature of surfaces at the first atomic layer. The thermal energy, non-charged beam of atoms used allows exploring samples without the destructive effects of energetic particles or electric charges, in addition to having no topographic limitations due to the aspect ratio or shape of a solid probe tip, and with resolution potentially far better than conventional far-field optical microscopes. Contrast mechanisms which produce surface composition information have long been known from atomic scattering experiments, such as by atomic diffraction from crystal surfaces or contrast due to surface roughness. These are now being explored in images for the first time.

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Section: Nam Imagesmentioning

confidence: 76%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Exploring neutral atom microscopy

Witham

Sánchez

2014

Crystal Research and Technology

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“…In general, contrast in helium images arises as a result of changes in the angular distribution of scattered helium atoms with location on the surface. Helium atom scattering (HAS) has long been used to study the properties of surfaces under high and ultra-high vacuum conditions, so the basic helium-surface interaction mechanisms are well understood [9][10][11][12] . For surfaces that are well defined at an atomic level, incoming helium atoms can reflect specularly when the surface appears flat, diffract from atomic corrugation, or interact inelastically with surface phonons in the material.…”

Section: Bergin * S M Lambrick H Sleath D J Ward J Ellimentioning

confidence: 99%

Observation of diffraction contrast in scanning helium microscopy

Bergin

Lambrick

Sleath

et al. 2020

Sci Rep

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Scanning helium microscopy is an emerging form of microscopy using thermal energy neutral helium atoms as the probe particle. The very low energy combined with lack of charge gives the technique great potential for studying delicate systems, and the possibility of several new forms of contrast. To date, neutral helium images have been dominated by topographic contrast, relating to the height and angle of the surface. Here we present data showing contrast resulting from specular reflection and diffraction of helium atoms from an atomic lattice of lithium fluoride. The signature for diffraction is evident by varying the scattering angle and observing sharp features in the scattered distribution. The data indicates the viability of the approach for imaging with diffraction contrast and suggests application to a wide variety of other locally crystalline materials.

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