bravel at bnl.gov
Mon Aug 8 10:35:04 CDT 2016
On 08/08/2016 11:19 AM, Carlos Triana Estupinan wrote:
> I want to know if it is possible to obtain a 3D structure (.cif file) of
> an amorphous material from the EXAFS fitting carried out from artemis. I
> mean, there is a way to extract a .cif file with the structural data
> obtained from the refined spectra.
EXAFS is basically a one-dimensional measurement. You measure R.
Multiple scattering gives you limited information about the 3D
arrangement of atoms, but mostly EXAFS is just R.
Unless I am misunderstanding the question, I don't think you can do what
you are asking even for a well-ordered crystal, much less an amorphous
> Also, in amorphous materials there
> must be a distribution of interatomic bond distances and coordination,
> and so, how can I address such a structural distribitions.
There is a while literature on the use X-ray or neutron scattering along
with EXAFS and molecular dynamics and monte carlo methods to study
amorphous materials. It seems that the most successful approaches
involve forward modeling -- i.e. testing structures against the EXAFS data.
There simply isn't enough information in EXAFS to invert the EXAFS and
extract a 3d configuration. Artemis does not even try to do that.
Bruce Ravel ------------------------------------ bravel at bnl.gov
National Institute of Standards and Technology
Synchrotron Science Group at NSLS-II
Building 743, Room 114
Upton NY, 11973
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