[Ifeffit] S02

[Dr. Paul Fons]

I was curious to tap the collective wisdom of those on the list 
regarding the "true meaning" of S02, the passive electron reduction 
factor, at least with regards to fitting experimental data to feff 
calculated paths.
I understand that S02 is an aggregate "energy losses related to core 
hole creation parameter", but am curious about experimental data 
fitting. In particular, I have have started probing both high and low 
energy ranges for exafs and find that my usual experience from the 
10-15 keV range don't seem to apply.  In particular, I have been 
measuring energies around the O edge (540 eV) as well as some rather 
high energies edges Te (31 keV), Cd (26.7 keV) etc..  I have heard 
(indirectly via my coworker) from Andrei Rogalev that he considers S02 
to be just another parameter. As the correlation between S02 and N is 
unity, this leads to a fair amount of ambiguity in the determination of 
coordination to say the least.  While we are on the subject, are there 
any general observations about the transferablility of S02 from 
standards.  How about the expected temperature dependence of S02? I do 
recall reading from John Rehr's article in RMP that S02 (which feff 
does calculate by the way) is an path dependent, complex sum that must 
be phasor summed.  What are some realistic approximations/trends 
regarding to S02 and temperature, energy, and/or structure dependence?







Dr. Paul Fons
Senior Researcher
National Institute for Advanced Industrial Science & Technology
METI
Optoelectronics Division
Umezono 1-1-4
Tsukuba, Ibaraki JAPAN 305-8568