[Ifeffit] Very large exafs amplitude in collected data - cause unknown (Jason Alvino)
segre at iit.edu
Mon Jun 10 23:18:23 CDT 2013
On Tue, 11 Jun 2013, Jason F. Alvino wrote:
> Hi Matt,
> As I pointed out before, in the attached zipfile, there is a file called
> "AuNP_anatase_Au.D" which has the data in two columns of energy vs mu,
> comma separated underneath the "EV RAW" header.
> It also already has all the bad channels removed from the averaged data.
Just doing a quick fit of your data with k 2-15 and R 1-6 and a bulk gold
model (all paths up to 8 A), gives an excellent fit with 5 parameters (R ~
2%). It basically looks like bulk Gold at low temperatures with an
amplitude reduction factor of 0.77 which is not too small. You are
correct that the sigma squared values are samll but that is to be expected
at 12K. I used an isotropic expansion/contraction parameter which fits to
-0.010, again consistent with thermal expansion at low temperatures.
It looks like you indeed have agglomeration because this data does not
seem to be from nanoparticles of gold.
Carlo U. Segre -- Duchossois Leadership Professor of Physics
Director, Center for Synchrotron Radiation Research and Instrumentation
Illinois Institute of Technology
Voice: 312.567.3498 Fax: 312.567.3494
segre at iit.edu http://phys.iit.edu/~segre segre at debian.org
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