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@millenia.cars.aps.anl.gov [mailto:ifeffit-bounces@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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