[Ifeffit] Question on Glitch in FEFF for Ru EXAFS measurements

Dooshaye Moonshiram dmoonshi at gmail.com
Mon Nov 26 16:05:17 CST 2012


Dear Bruce,

I recently collected EXAFS data on the *Tris(bipyridine)ruthenium(II)
dichloride Ru 2 compound-photosensitizer in solution form. In order to
compare EXAFS data to XRD data, I uploaded the XRD coordinates of this
crystal structure from cambridge database in a FEFF calculation page in
ARTEMIS. I ran FEFF on the x,y and z coordinates of this standard compound
in Artemis and summed all paths to compare with my experimental
data(collected in solution form in fluorescence mode)*
*I have 2 problems*
*1) I found a glitch when running FEFF in ARTEMIS. In order to compare XRD
coordinates to EXAFS data, I upload the XRD coordinates in a FEFF
calculation page, run FEFF and sum all paths.  Now*
*a) **f I upload the XRD coordinates in a FEFF calculation page without
having the EXAFS artemis file present, I get different fits compared to*
*b)  if I first upload the EXAFS  experimental file and then run FEFF on
the XRD cartesian coordinates. It seems that **the sum of all paths from
the FEFF calculation page tend to mimic the experimental EXAFS file which
has first been uploaded and is not a true presentation of how the FT should
be.*
*
*
*-Please let me know if this is unclear and I can send you my EXAFS file as
well as the XRD coordinates which I obtained from Cambridge structural
databse*
*
*
*2) Another problem which I have with my EXAFS data is that I have a peak
at 2.5 Angstrom which does not match XRD coordinates and is not present if
I run FEFF on XRD coordinates only(true comparison as  I don't add the the
experimental file in Artemis). Could this peak be due to the Ru standard
somehow? All measurements were done in fluorescence mode (F/Io) at 20 K in
cryostat using a germanium detector. I  simultaneously collected EXAFS
measurements on Ru metal standard between Iref and IT ionization chambers.*
*
*
*Thank you for your help,*
*Sincerely*
*Best Regards*
*Dooshaye Moonshiram*
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