The tiny peak at 2.3 A can either come from a low Z back scatterer like C or it can be the spectral leak from the first shell O atom. It is hard for me to comment with certainty from the information you have provided. I can better comment by looking at the real part of the FT data, or an ATHENA project file might actually help. Alternatively, you can describe your system and that may lead to an educated guess.

From what you have sent, I can see clear differences in sample 1 and sample 2. The amplitude of the FT data of sample 2 is lower than sample 1, which means it might have 1) mixed first shell environment, or 2) destructive interference with the second shell atom. These are of course very broad suggestions to get you thinking. If you are working on environmental systems, you may consider looking into these two papers for additional clues:

On Thu, Jan 6, 2011 at 1:23 AM, Alan Du <alan.jianhong.du@gmail.com> wrote:

Hi all,

I processed my XAS data and compare them with standards from Farrel Lytle Database. (http://img717.imageshack.us/i/xasw.jpg/).

In the RSF, both sample 1 and 2 has a major peak at R = ca. 1.8 A. sample 1 has an additional peak at R = ca. 2.3 A. I wonder if this tiny peak is significant.

It seems both samples has peak positions similar to those of CdO standard, which sound logical because the cadmium will bind to the surface oxygen of the material.

I looking at fitting sample 1 and 2 using whatever crystallographic info of CdO I can get my hands on.

Wonder if the plan make sense.

Happy new year,
Alan

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