[Ifeffit] question about Eo and simultaneous fitting

[Anatoly Frenkel]

It is true that in many cases oxidation/reduction affects the low k-range
behavior in chi(k), but if the second shell (metal-metal) frequency is not
affected, the data can still be aligned by focusing at the high k-portion of
the data, so what Shelly suggested, may be, in principle, done.

Anatoly


-----Original Message-----
From: ifeffit-bounces at millenia.cars.aps.anl.gov
[mailto:ifeffit-bounces at millenia.cars.aps.anl.gov] On Behalf Of Scott Calvin
Sent: Wednesday, February 14, 2007 10:55 AM
To: XAFS Analysis using Ifeffit
Subject: Re: [Ifeffit] question about Eo and simultaneous fitting

Hi Shelly,

Interesting--I've never tried that method with samples that I expect 
to differ in oxidation state. If it's differing in oxidation state, 
the local environment is probably different too...particularly, 
nearest-neighbor distances should be changed significantly. So how do 
you align the chi(k) data with each other, when they oscillate at a 
different frequency?

--Scott Calvin
Sarah Lawrence College

At 10:38 AM 2/14/2007, you wrote:

>The approach that I like to take, is to vary the choice of E0 in the
>background subtraction step so that the chi(k) spectra are well aligned
>with each other and the theory.  Then only one Ezero parameter is
>needed.
>
>Cheers,
>Shelly

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