Hi Chris,
Multiple scattering can be quite important, particularly in systems with
higher local symmetry
(i.e. focused multiple scattering - many equivalent paths). It occurs
along with back-scattering,
so you should include the Fe-N1 path. Conveniently, you can constrain
the MS path based on
the back-scattering - i.e. the MS distance is dependent on the
back-scatter distances and
scattering angle...you can also constrain the msrd (e.g. add in
quadrature).
Prof. Dr. Thorsten Ressler's program "WinXAS" has the constraints as
options built in...very convenient.
cheers,
-R.
On 2024-04-02 4:18 p.m., Chris Pollock wrote:
Hi everyone, I've been using Artremis for quite a while, but have only
recently come across a case where the inclusion of multiple scattering
seems to be important for fitting some data and wanted to ask what is
probably a super basic question
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Hi everyone,
I've been using Artremis for quite a while, but have only recently
come across a case where the inclusion of multiple scattering seems to
be important for fitting some data and wanted to ask what is probably
a super basic question to make sure I don't mess anything up.
I've recently collected some data on a metalloenzyme with a quite
histidine-rich active site and, since it's been shown previously that
multiple scattering is important for fitting the longer range
scattering for these types of systems, I wanted to make sure I capture
this in my Artemis fits. The data appear to show scattering
contributions from N3, C2, and N1 in the imidazole ring, and FEFF
seems to agree that those paths are the most important, though it
calculates the MS intensity to be significantly greater than the
single scattering for the farther N (N1). So, my super naive question
is: To include multiple scattering paths in the fits--say, the
Fe-N3-N1 triangle--is it correct to include the Fe-N3-N1 multiple
scattering path in addition to the Fe-N3 and Fe-N1 single scattering
paths, or would that effectively be double counting the farther
nitrogen (N1)?
Thanks in advance!
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