[Ifeffit] How to keep enot, delr, and ss within acceptable limits

K.A. Swat kaswat at gmail.com
Mon Jan 12 02:30:52 CST 2009


Dear all,

I have the same problem with Hashem.

My sample is nanocrystal Wurtzite InN (XRD and AFM results). I do the
absorption experiment at In L3-edge at room temperature. After an data
processing process, I get 2 broad peaks in FT. When i try to fitting a
Wurtzite InN model to the EXAFS spectra for the first and second shells, I
always get unacceptable parameters. First of all, I try to change my WZ InN
model (changing lattice constant a and c, u-parameter) but it is
inefficiently. How could I do?

This figure 1 shown a FT of In-L3 EXAFS spectra, the Blue line is my 2 broad
peaks and red line is calculate with my WZ InN model which set all parameter
to initial value (not guess any thing).

figure 1 >> http://nanotech.sytes.net/kaswat/01.emf

After I have read Bruce's mail ("If your sigma^2 parameter is negative,
perhaps you have too much structural disorder in your model and the fit is
compensating by inflating those paths with a negative sigma^2."). How do I
construct a WZ InN model which have too many structural disorder.

P.S. I have read some papers, they have use model of nanocrystalline alloy
which containing amorphous model. How to construct an amorphous model like
they.


-- 
Mr. Kittiphong Amnuyswat [kaswat]

Post Graduate student
College of KMITL Nanotechnology

Contact : kaswat at gmail.com, nakz_zz at hotmail.com [MSN Available]
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