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SUMMARY:Quantitative Characterisation of Catalyst Nanoparticles using STEM
  - Kate MacArthur\, Ernst Ruska Centre\, Forschungszentrum Juelich
DTSTART:20160225T140000Z
DTEND:20160225T150000Z
UID:TALK63338@talks.cam.ac.uk
CONTACT:Duncan Johnstone
DESCRIPTION:Platinum-based catalysts for hydrogen fuel-cell applications h
 ave progressed greatly with the addition of a second element in either a m
 ixed-alloy or core-shell structure. Not only does this result in a reducti
 on in mass of expensive platinum metal used\, but such particles seem to d
 emonstrate significantly higher catalytic activity. Further improvement of
  these systems can only be made by careful investigations on their atomic-
 scale structure and composition.\n\nIn the same way that the scattering cr
 oss section\, σ\, can be calculated from annular dark-field (ADF) scannin
 g transmission electron microscopy (STEM) image intensity and for ionizati
 on edges in electron energy loss spectroscopy (EELS)\, it is possible to c
 alculate an energy dispersive x-ray (EDX) partial ionization cross section
 .  The approach which is very similar to the ζ-factor method proposed by 
 Watanabe is beneficial especially because of the simplicity of its impleme
 ntation. I will discuss the advantages of such an approach and its applica
 tion to the study of bimetallic catalyst nanoparticles.\nOnce we have a me
 thod for quantification of EDX using cross sections we can then begin to e
 xploit the ability to combine such cross sections with those determined us
 ing STEM or EELS. The additional image provided on a column by column basi
 s may yield the solutions to extracting 3-dimensional information about bi
 metallic nanoparticles which has otherwise been difficult.
LOCATION:LT Goldsmith 1 Materials Science and Metallurgy\, Department of
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