No shift in XANES absorption peak
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
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@iit.edu http://phys.iit.edu/~segre segre@debian.org
Hi Disha,
The shift in bond distance in this case, is not necessarily associated
with the change of oxidation state. It can be simply caused by the
insertion/removal of Li/Na or whatever depending on your battery type
during the charge/discharge, which sometimes changes the oxidation state of
Mn slightly, sometimes doesn't.
Regards,
On Sun, Jun 10, 2018 at 11:34 PM, Disha Gupta
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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participants (3)
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Carlo Segre
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Disha Gupta
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Qingying Jia