Re: [Ifeffit] No shift in XANES absorption peak

Hi Disha, For such a huge shit of bond distance, the corresponding lattice constant change should be readily seen by XRD. It will also shift the XANES edge slightly. Regards, On Mon, Jun 11, 2018 at 10:58 AM, Disha Gupta wrote:

Dear Claudia, Qingying Jia, Matt

Thank you so much for your responses :)

The shift in bond length I see is almost around 0.1-0.12 Angstrom, which is not small enough to ignore. I think the coordination might be changing, if not the oxidation state. I will redo the Artemis calculations with N as a variable again to see if that helps. Because keeping my N constant actually gave me pretty low Debye-Waller values and R factor was also below 5% so I was assuming the fits were reliable.

I was also thinking maybe Mn is undergoing partial oxidation, however, in bulk we do not see that change in the main XANES absorption peak. I am not sure if that can be a possibility.

Thanks a lot again! Kind Regards Disha

Disha Gupta Graduate Student School of Materials Science and Engineering Nanyang Technological University (NTU), Singapore +65 84087404 DISHA001@e.ntu.edu.sg

On Mon, Jun 11, 2018 at 10:14 PM, wrote:

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Today's Topics:

1. Re: Demeter on Windows 10 does not work (sikolen) 2. Re: No shift in XANES absorption peak (Claudia Schnohr) 3. Re: No shift in XANES absorption peak (Qingying Jia) 4. Re: Demeter on Windows 10 does not work (Matt Newville) 5. Re: No shift in XANES absorption peak (Matt Newville)

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Message: 1 Date: Mon, 11 Jun 2018 13:39:03 +0200 From: sikolen To: XAFS Analysis using Ifeffit Subject: Re: [Ifeffit] Demeter on Windows 10 does not work Message-ID: Content-Type: text/plain; charset=UTF-8; format=flowed

Thanks Kathy,

It seems the problem is really with the wrong path... Now I see how to fix it.

Vadim

On 2018-06-08 17:07, Kathy Dardenne wrote:

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Dear Vadim,

I am running myself Demeter 0.9.26, 64bit under win10 and do not have such trouble. But your description is similar to the problem occurring with the previous release of Demeter 0.9.26 pre2 (old path for gnuplot executable in ini file leading the same effect), did you download the actual version for Demeter 0.9.26? this later trouble is fixed and Demeter runs smoothly with win7 and win10.

Kathy

-----Message d'origine----- De?: Ifeffit De la part de sikolen Envoy??: vendredi 25 mai 2018 10:01 ??: ifeffit@millenia.cars.aps.anl.gov Objet?: [Ifeffit] Demeter on Windows 10 does not work

Dear all,

I've just changed my loving Windows-7 to the new Windows-10. I've installed Demeter (v.0.9.26, 64-bit), but it does not work: cmd-Windows appears for the a couple of seconds and disappears forever. Is it already known problem of the OS? Sorry, may be this question already appeared here, I just missed it.

Vadim -- *********************************** Dr. Vadim Sikolenko Senior Scientist Frank Laboratory of Neutron Physics Vadim.Sikolenko@jinr.ru Skype: svadimm ********************************** _______________________________________________ Ifeffit mailing list Ifeffit@millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit Unsubscribe: http://millenia.cars.aps.anl.gov/mailman/options/ifeffit

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-- *********************************** Dr. Vadim Sikolenko Senior Scientist Frank Laboratory of Neutron Physics Vadim.Sikolenko@jinr.ru Skype: svadimm **********************************

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Message: 2 Date: Mon, 11 Jun 2018 14:56:22 +0200 From: Claudia Schnohr To: ifeffit@millenia.cars.aps.anl.gov Subject: Re: [Ifeffit] No shift in XANES absorption peak Message-ID: <20180611145622.Horde.4UvsqRy3fmqp-P5XNJL1uln@webmail.uni-jena.de

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Content-Type: text/plain; charset=utf-8; format=flowed; DelSp=Yes

Dear Disha,

In principle, yes, there can be a change of bond length without a notable change of the XANES. But it also depends on how large the bond length changes are that you observe.

I have studied a lot of semiconductor alloys, for example (In,Ga)P or Cu(In,Ga)Se2 where the Ga and In atoms share the same lattice site. They are always coordinated to four P or Se atoms, respectively, but the bond lengths change by 0.02 to 0.03 A because the size of the unit cell changes with In/Ga ratio. At the same time, the Ga and In XANES is completely unaffected by a change of the In/Ga ratio. If you are interested in this, you may have a look at Phys. Rev. B 85, 245204 (2012), J. Appl. Phys. 116, 093703 (2014), or Appl. Phys. Rev. 2, 031304 (2015).

This is just to say that, yes, in some special cases you can have a change of bond length without a change of XANES. There can be lot's of other things going on, too :)

Cheers, Claudia

----- Nachricht von Disha Gupta --------- Datum: Mon, 11 Jun 2018 18:29:49 +0800 Von: Disha Gupta Antwort an: XAFS Analysis using Ifeffit Betreff: Re: [Ifeffit] No shift in XANES absorption peak An: ifeffit@millenia.cars.aps.anl.gov

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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 Date: Mon, Jun 11, 2018, 12:34 Subject: Re: [Ifeffit] No shift in XANES absorption peak To: XAFS Analysis using Ifeffit

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:

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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 _______________________________________________ Ifeffit mailing list Ifeffit@millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit Unsubscribe: http://millenia.cars.aps.anl.gov/mailman/options/ifeffit

Disha Gupta Graduate Student School of Materials Science and Engineering Nanyang Technological University (NTU), Singapore +65 84087404 DISHA001@e.ntu.edu.sg

On Mon, Jun 11, 2018 at 11:34 AM, 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

----- Ende der Nachricht von Disha Gupta -----

-- PD Dr. Claudia S. Schnohr Institut f?r Festk?rperphysik Friedrich-Schiller-Universit?t Jena Max-Wien-Platz 1 D-07743 Jena Germany

Tel: +49 3641 947333 Fax: +49 3641 947302

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Message: 3 Date: Mon, 11 Jun 2018 09:59:23 -0400 From: Qingying Jia To: XAFS Analysis using Ifeffit Subject: Re: [Ifeffit] No shift in XANES absorption peak Message-ID: Content-Type: text/plain; charset="utf-8"

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 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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