question about Eo and simultaneous fitting
Hi, first I would like to thank all experienced people answering in this forum!! I have learned really a lot from you. And now my question: Should I fit EXAFS spectra of a doped material and the same material, but oxidized and reduced (three spectra) simultaneously? In my opinion: yes, as I am looking for small differences. Is varying one Eo for the three samples the right approach? I am also wondering, should I vary one Eo for samples with different doping concentrations? Thank you for any hint! Tony ____________________________________________________________________________________ It's here! Your new message! Get new email alerts with the free Yahoo! Toolbar. http://tools.search.yahoo.com/toolbar/features/mail/
Hi Tony, A quick answer before I try to fight my way through an ice storm to get to work. :) Fitting the three spectra simultaneously makes sense, but if oxidation state is expected to be different, then you really need different E0's. As far as doping, it depends on the details. In some cases, it may require a different E0's, in others, not. Of course, you can try it both ways, and see what the fits think. --Scott Calvin Sarah Lawrence College At 05:04 AM 2/14/2007, you wrote:
Hi,
first I would like to thank all experienced people answering in this forum!! I have learned really a lot from you.
And now my question: Should I fit EXAFS spectra of a doped material and the same material, but oxidized and reduced (three spectra) simultaneously? In my opinion: yes, as I am looking for small differences. Is varying one Eo for the three samples the right approach? I am also wondering, should I vary one Eo for samples with different doping concentrations?
Tony --
Should I fit EXAFS spectra of a doped material and the same material, but oxidized and reduced (three spectra) simultaneously? In my opinion: yes, as I am looking for small differences. Is varying one Eo for the three samples the right approach? I am also wondering, should I vary one Eo for samples with different doping concentrations?
I think you need to be more specific about what your samples are and what you're trying to learn from them. For example, I could read your question as meaning you have samples of Mn K edge for Mn doped into silicon ("a doped material") Si K edge of pure silicon ("same material, reduced") Si K edge of quartz ("same material, oxidized") In which case, I don't see that see much to be gained by fitting the spectra together. In general, one fits multiple spectra together when it is expected that there is a relationship between the different coordination environments, most usually a simple relationship between the g(R)'s for the different samples. E0 is typically different for each sample. There are situations where they can be constrained to be the same, such as spectra are all on the same sample at different temperatures. For more specific answers, please ask more specific questions. --Matt
participants (3)
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Matt Newville
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Scott Calvin
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tony vitova