PCA works only if there are series of spectra with change in the makeup of S species, not for a single spectrum.
Anatoly
----- Original Message -----
From: ifeffit-bounces@millenia.cars.aps.anl.gov
To: ifeffit@millenia.cars.aps.anl.gov
Sent: Sun Oct 26 13:05:32 2008
Subject: Re: [Ifeffit] Fit XANES spectra using Athena
Jenny,
I'm relatively new to the community XAFS, and have not done any sulfur work thus far... but have you considered doing a principal component analysis on the XANES of your samples?
This method should help you identify how many phases are present (assuming that all of your samples aren't exactly identical; however the maximum number of independent phases it will return is the number of samples you tested), and with your standards you might be able to eliminate some of the phases (from the standards) as well as identify some of the phases that are in your sample.
(There is software that will do this in the IFFEFIT package under Sixpack --> 'pc analysis')
Andrew Campos
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