[Ifeffit] Ifeffit Digest, Vol 114, Issue 5 - Mn XANES
Andrew Korinda
a-korinda at northwestern.edu
Thu Aug 9 10:37:39 CDT 2012
Manceau also describes his arc-tangent function in his earlier work
(Mn is also my focus):
Manceau, A.; Gorshkov, A. I.; Drits, V. A., Am. Mineral. 1992, 77
(11), 1133-1143.
I've found Farges to be a little vague on how he extracts the pre-edge
features for fitting.
Andy K.
On Thu, Aug 9, 2012 at 10:05 AM, Matthew Marcus <mamarcus at lbl.gov> wrote:
> You might also consider the method given in:
> Manceau, A., Marcus, M. A., Grangeon, S. (2012) "Determination of Mn valence
> states in mixed-valent magnanates by XANES spectroscopy", American
> Mineralogist 97,816-827
>
> (not that I'm plugging my own work or anything :-) )
> Marcus, M. A.
>
> On 8/9/2012 7:53 AM, Enyuan Hu wrote:
>>
>> Hi Dominik,
>>
>> Thank you so much for your quick response. Indeed, it's really nice
>> fitting according to your result. But my situation seems a little bit
>> different as I'm dealing with the Mn XANES data and there're doublets and
>> sometimes triplets in the pre-edge. Actually, I might as well explain my
>> interest of doing such fitting. I read in the paper _(F Farges, PHYSICAL
>> REVIEW B 71, 155109 (2005))_ that the centroid of pre-edge peak is a more
>> accurate measurement of the oxidation state of the element of interest,
>> compared to the more conventional inflection point or half-way method. So I
>> was trying to follow the paper and see if it also works for my samples.
>> Anyway, thanks again for your help!
>>
>> Enyuan
>>
>> On Thu, Aug 9, 2012 at 9:11 AM, <ifeffit-request at millenia.cars.aps.anl.gov
>> <mailto:ifeffit-request at millenia.cars.aps.anl.gov>> wrote:
>>
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>> Today's Topics:
>>
>> 1. Re: question for ifeffit mailing list - ATHENA NORMALIZATION
>> (Marie Zwetsloot)
>> 2. Re: question for ifeffit mailing list - ATHENA NORMALIZATION
>> (Scott Calvin)
>> 3. pre-edge centroid (Enyuan Hu)
>> 4. Re: pre-edge centroid (Dominik Samuelis)
>>
>>
>> ----------------------------------------------------------------------
>>
>> Message: 1
>> Date: Wed, 8 Aug 2012 13:17:59 -0400
>> From: Marie Zwetsloot <mjz56 at cornell.edu <mailto:mjz56 at cornell.edu>>
>> To: ifeffit at millenia.cars.aps.anl.gov
>> <mailto:ifeffit at millenia.cars.aps.anl.gov>
>> Subject: Re: [Ifeffit] question for ifeffit mailing list - ATHENA
>> NORMALIZATION
>> Message-ID:
>>
>> <CALtZdD54=1-w4U3vk7DdNU_CUkGpK-1vJ3ioOR_CSvkj4UeCXw at mail.gmail.com
>> <mailto:1-w4U3vk7DdNU_CUkGpK-1vJ3ioOR_CSvkj4UeCXw at mail.gmail.com>>
>> Content-Type: text/plain; charset="iso-8859-1"
>>
>> Hi Scott Calvin,
>>
>> Thanks for your help. Yes, this is as far as my pre- and post-edge
>> range
>> go. I realized I should have made them longer; it was my first time
>> doing
>> this and wasnt aware that i should lengthen my pre and post-edge for
>> later
>> on analysis. This will be good lesson for the future.
>>
>> So you would not recommend doing linear combination fitting? I was
>> planning
>> on trying it out.. But I wouldnt want to do it if with my pre- and
>> post-edge range, I am bound to derive wrong conclusions from the data.
>>
>> Best,
>> Marie
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>> ------------------------------
>>
>> Message: 2
>> Date: Wed, 8 Aug 2012 15:10:16 -0400
>> From: Scott Calvin <scalvin at sarahlawrence.edu
>> <mailto:scalvin at sarahlawrence.edu>>
>> To: XAFS Analysis using Ifeffit <ifeffit at millenia.cars.aps.anl.gov
>> <mailto:ifeffit at millenia.cars.aps.anl.gov>>
>> Subject: Re: [Ifeffit] question for ifeffit mailing list - ATHENA
>> NORMALIZATION
>> Message-ID: <B36E3403-35BC-48BE-8E4D-AE2CB8556769 at slc.edu
>> <mailto:B36E3403-35BC-48BE-8E4D-AE2CB8556769 at slc.edu>>
>> Content-Type: text/plain; charset="iso-8859-1"
>>
>> Hi Marie,
>>
>> I think you can try linear combination fitting, but you'll have to
>> build in the uncertainty in normalization in to your own estimates of
>> uncertainty.
>>
>> If you don't check the box that says "force weights to sum to 1," then
>> you can allow for normalization errors in your sample.
>>
>> If your standards also have only short energy ranges, then there's
>> nothing you can do about that, though. As I said, you'll just have to build
>> them in to your uncertainty. If you are unsure of the edge jump of a
>> standard to 20%, then the contribution of that standard to the linear
>> combination fit is uncertain by 20%.
>>
>> Uncertainty in normalization is one of the leading contributions to
>> the uncertainty that should be associated with linear combination fitting,
>> even when the energy ranges are sufficient. In a case like yours, they're
>> bigger than they could have been, but it doesn't mean you can't use linear
>> combination analysis at all.
>>
>> --Scott Calvin
>> Sarah Lawrence College
>>
>> On Aug 8, 2012, at 1:17 PM, Marie Zwetsloot wrote:
>>
>> > Hi Scott Calvin,
>> >
>> > Thanks for your help. Yes, this is as far as my pre- and post-edge
>> range go. I realized I should have made them longer; it was my first time
>> doing this and wasnt aware that i should lengthen my pre and post-edge for
>> later on analysis. This will be good lesson for the future.
>> >
>> > So you would not recommend doing linear combination fitting? I was
>> planning on trying it out.. But I wouldnt want to do it if with my pre- and
>> post-edge range, I am bound to derive wrong conclusions from the data.
>> >
>> > Best,
>> > Marie
>> > _______________________________________________
>> > Ifeffit mailing list
>> > Ifeffit at millenia.cars.aps.anl.gov
>> <mailto:Ifeffit at millenia.cars.aps.anl.gov>
>> > http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit
>>
>>
>>
>>
>> ------------------------------
>>
>> Message: 3
>> Date: Thu, 9 Aug 2012 00:21:14 -0400
>> From: Enyuan Hu <bearcharge at gmail.com <mailto:bearcharge at gmail.com>>
>> To: ifeffit <ifeffit at millenia.cars.aps.anl.gov
>> <mailto:ifeffit at millenia.cars.aps.anl.gov>>
>> Subject: [Ifeffit] pre-edge centroid
>> Message-ID:
>>
>> <CAJud35NRYb67J7xLATPHPJGjEyvOK_gUKZur+dL9T30x8k=UHA at mail.gmail.com
>> <mailto:UHA at mail.gmail.com>>
>> Content-Type: text/plain; charset="iso-8859-1"
>>
>> Dear all,
>>
>> I was wondering if anyone could comment on how to get the centroid of
>> pre-edge by fitting the pre-edge peak by pseudo-Voigt functions. I
>> tried to
>> do that in Athena, but it seemed that peaking fitting part is the
>> relatively less developed function in the software. Any comment would
>> be
>> appreciated.
>>
>> Enyuan
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>> ------------------------------
>>
>> Message: 4
>> Date: Thu, 09 Aug 2012 15:11:31 +0200
>> From: Dominik Samuelis <d.samuelis at fkf.mpg.de
>> <mailto:d.samuelis at fkf.mpg.de>>
>> To: XAFS Analysis using Ifeffit <ifeffit at millenia.cars.aps.anl.gov
>> <mailto:ifeffit at millenia.cars.aps.anl.gov>>
>> Subject: Re: [Ifeffit] pre-edge centroid
>> Message-ID: <5023B703.6020609 at fkf.mpg.de
>> <mailto:5023B703.6020609 at fkf.mpg.de>>
>> Content-Type: text/plain; charset="iso-8859-1"; Format="flowed"
>>
>> Dear Enyuan,
>>
>> in my experience, peak fitting works very well with Athena. Try not to
>> fit only the prepeak, but maybe include an arctan describing the edge
>> (see attached pdf, the fit was made using athena). This makes
>> isolating
>> the prepeak much more reliable.
>>
>> Best regards,
>> Dominik
>>
>> On 09.08.2012 06:21, Enyuan Hu wrote:
>> > Dear all,
>> >
>> > I was wondering if anyone could comment on how to get the centroid
>> of
>> > pre-edge by fitting the pre-edge peak by pseudo-Voigt functions. I
>> tried
>> > to do that in Athena, but it seemed that peaking fitting part is
>> the
>> > relatively less developed function in the software. Any comment
>> would be
>> > appreciated.
>> >
>> > Enyuan
>> >
>> >
>> > _______________________________________________
>> > Ifeffit mailing list
>> > Ifeffit at millenia.cars.aps.anl.gov
>> <mailto:Ifeffit at millenia.cars.aps.anl.gov>
>> > http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit
>> >
>>
>>
>> --
>> Dr. Dominik Samuelis
>> d.samuelis at fkf.mpg.de <mailto:d.samuelis at fkf.mpg.de>
>> Max-Planck-Institut f?r Festk?rperforschung
>> Max Planck Institute for Solid State Research
>> Heisenbergstr. 1
>> 70569 Stuttgart
>> Germany
>> Phone +49-711-689-1769 <tel:%2B49-711-689-1769>
>> Fax +49-711-689-1722 <tel:%2B49-711-689-1722>
>> Web http://www.fkf.mpg.de/maier/
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>> ------------------------------
>>
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>> End of Ifeffit Digest, Vol 114, Issue 5
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