Moneeb,
I'm in the middle of beam run, so I am forwarding this along to the
Ifeffit mailing list for commentary.
B
---------- Forwarded Message from Moneeb Shatnawi > ----------
Subject: average first shell position and width
Date: Wednesday 27 June 2007
From: Moneeb Shatnawi
To: Bruce Ravel
Dear Dr. Ravel,
Hello,
I am Moneeb Shatnawi from physics department at Michigan State University,
I have a PDF and XAFS data on GeSe system, and I would like to check if
the PDF and XAFS results are consistent with each other in terms of the
first PDF peak position and width.
The first PDF peak in this system is a mixed shell of Se-Se bonds as
well as Ge-Se bonds.
The PDF data gave a width of the first PDF peak of about 0.06 A, and the
XAFS data gave sigma^2 for Ge-Se bond is 0.006 A^2, and for Se-Se bond
is 0.003 A^2.
How is sigma in XAFS results (I was using Artemis program) related to
the width of the first PDF peak?
Also, when obtaining the XAFS fits to the data, I was using: Theory
---> first shell fit.
In this, I was giving r_eff for Se-Se bond to be 2.32 A and that for
Ge-Se to be 2.368 A. Through the XAFS refinement, I obtained r, dr as
well as r_eff.
which of these should be considered as the actual bond length (r or r_eff)?
and how are these related to the average position that I get from
fitting the first PDF peak in this system?
I appreciate your help,
Thanks,
Moneeb
-------------------------------------------------------
--
Bruce Ravel ---------------------------------------------- bravel@anl.gov
Molecular Environmental Science Group, Building 203, Room E-165
MRCAT, Sector 10, Advanced Photon Source, Building 433, Room B007
Argonne National Laboratory phone and voice mail: (1) 630 252 5033
Argonne IL 60439, USA fax: (1) 630 252 9793
My homepage: http://cars9.uchicago.edu/~ravel
EXAFS software: http://cars9.uchicago.edu/~ravel/software/
