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SUMMARY:2D Helium Atom Diffraction from a Microscopic Spot - Nick von Jein
 sen\, Surface and 2D Nanoscience\, Cavendish Laboratory
DTSTART:20240201T150000Z
DTEND:20240201T160000Z
UID:TALK209719@talks.cam.ac.uk
CONTACT:Stephen Walley
DESCRIPTION:A method for measuring helium atom diffraction with micron-sca
 le spatial resolution is demonstrated in a scanning helium microscope (SHe
 M) and applied to study a micron-scale spot on the (100) plane of a lithiu
 m fluoride (LiF) crystal. The positions of the observed diffraction peaks 
 provide an accurate measurement of the local lattice spacing\, while a com
 bination of close-coupled scattering calculations and Monte Carlo ray-trac
 ing simulations reproduce the main variations in diffracted intensity. Sub
 sequently\, the diffraction results are used to enhance image contrast by 
 measuring at different points in reciprocal space. The results open up the
  possibility for using helium microdiffraction to characterize the morphol
 ogy of delicate or electron-sensitive materials on small scales. These inc
 lude many fundamentally and technologically important samples which cannot
  be studied in conventional atom scattering instruments\, such as small gr
 ain size exfoliated 2D materials\, polycrystalline samples\, and other sur
 faces that do not exhibit long-range order.
LOCATION:Mott Seminar Room\, Cavendish Laboratory
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