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SUMMARY:Unlocking new materials for the hydrogen economy - Paul Dastoor\, 
 Department of Physics\, University of Newcastle\, New South Wales\, Austra
 lia
DTSTART:20251106T150000Z
DTEND:20251106T160000Z
UID:TALK236671@talks.cam.ac.uk
CONTACT:Stephen Walley
DESCRIPTION:Hydrogen embrittlement in metals and alloys\, which occurs fol
 lowing hydrogen adsorption\, is a well-documented failure mechanism where 
 hydrogen diffusion leads to material degradation through various processes
 \, such as hydride formation. Conventional microscopy struggles to detect 
 hydrogen due to its low electron density and minimal electron/X-ray cross-
 section\, making direct imaging challenging. In contrast\, neutral atom mi
 croscopy offers a novel approach to surface imaging. Specifically\, hydrog
 en has a high scattering cross-section for the extremely low-energy helium
  atom beams used in the scanning helium atom microscope (SHeM). This large
  cross-section enables highly sensitive\, non-destructive imaging of hydro
 gen-passivated surfaces for the first time. This paper presents the initia
 l SHeM imaging of hydrogen-passivated silicon (H/Si(111)) surfaces\, revea
 ling distinct contrast between passivated and non-passivated regions acros
 s millimetre-scale lateral dimensions. The resulting images highlight surf
 ace defects and wetting-induced structures within the hydrogen passivation
  layers. Helium atom scattering experiments confirm that passivated areas 
 exhibit ordered surface diffraction aligned with the Si(111) lattice struc
 ture\, whereas non-passivated regions show no significant diffraction sign
 al. Additionally\, thermal desorption spectroscopy (TDS) studies identify 
 desorption peaks corresponding to mono-\, di-\, and tri-hydride formation\
 , aligning with observed variations in scattered helium intensity. These f
 indings underscore the potential of SHeM as a powerful tool for probing th
 e initiation and evolution of hydrogen adsorption and desorption on surfac
 es.
LOCATION:Seminar Room West\, Room A0.015\, Ray Dolby Centre\, Cavendish La
 boratory
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