[Ifeffit] No shift in XANES absorption peak

[Disha Gupta]

 Dear Dr Carlo

The edges are almost identical. The pre-edge intensity change isn't that
significant I feel. I did the Artemis fittings with the coordination
numbers fixed. Maybe I can try varying the coordination numbers and see if
it gives a different result.
I have attached the images of the pre-edge and main peak.





Thanks and Regards
Disha




From: Carlo Segre <segre at iit.edu>
Date: Mon, Jun 11, 2018, 12:34
Subject: Re: [Ifeffit] No shift in XANES absorption peak
To: XAFS Analysis using Ifeffit <ifeffit at millenia.cars.aps.anl.gov>



Hi Disha:

it would be good to see the XANES you are referring to.  Are the edges
identical or do they change but not shift significantly?  Is the
coordination number also constant?  Generally, the bond distance will
change with oxidation state if the coordination number is constant but if
the coordination number changes, then there could be a change in bond
length too.

Cheers,

Carlo


On Mon, 11 Jun 2018, Disha Gupta wrote:

> Dear All
>
> Firstly, I would like to say sorry if I have missed out on this discussion
> before but it would be great if you could help me out.
> I have been analyzing some Mn K-edge XAS data for some battery materials.
> While the XANES data shows no shift in the main absorption peak which
means
> that there is no oxidation change happening, however, when I am fitting
the
> data in Artemis, I can see a shift in the bond lengths suggesting an
> oxidation change. Is it possible that bond lengths change even though
XANES
> spectra show no change?
>
>
> Thank you and Kind Regards
> Disha
>

-- 
Carlo U. Segre -- Duchossois Leadership Professor of Physics
Interim Chair, Department of Chemistry
Director, Center for Synchrotron Radiation Research and Instrumentation
Illinois Institute of Technology
Voice: 312.567.3498            Fax: 312.567.3494
segre at iit.edu   http://phys.iit.edu/~segre   segre at debian.org
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Disha Gupta
Graduate Student
School of Materials Science and Engineering
Nanyang Technological University (NTU), Singapore
+65 84087404
DISHA001 at e.ntu.edu.sg


On Mon, Jun 11, 2018 at 11:34 AM, Disha Gupta <dsha.91 at gmail.com> wrote:

> Dear All
>
> Firstly, I would like to say sorry if I have missed out on this discussion
> before but it would be great if you could help me out.
> I have been analyzing some Mn K-edge XAS data for some battery materials.
> While the XANES data shows no shift in the main absorption peak which means
> that there is no oxidation change happening, however, when I am fitting the
> data in Artemis, I can see a shift in the bond lengths suggesting an
> oxidation change. Is it possible that bond lengths change even though XANES
> spectra show no change?
>
>
> Thank you and Kind Regards
> Disha
>
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