Re: [Ifeffit] Linear Combination Fitting using ATHENA

at > out yourself because many of the spectra were done with a reference foil. > mam > - Original Message - > > *From:* Teck Kwang Choo > *To:* XAFS Analysis using Ifeffit > *Sent:* Wednesday, August 14, 2013 1:07 AM > *Subject:* Re: [Ifeffit] Linear Combination Fit

Re: [Ifeffit] Linear Combination Fitting using ATHENA

al Message - From: Teck Kwang Choo To: XAFS Analysis using Ifeffit Sent: Wednesday, August 14, 2013 1:07 AM Subject: Re: [Ifeffit] Linear Combination Fitting using ATHENA Yes Matthew, I used 7112 eV for my Fe K-edge calibration. I am guessing that is the reason a ~+1 eV shift in your

Re: [Ifeffit] Linear Combination Fitting using ATHENA

Some > people use other > values like 7112eV. > mam > > - Original Message - > *From:* Teck Kwang Choo > *To:* XAFS Analysis using Ifeffit > *Sent:* Tuesday, August 13, 2013 9:20 PM > *Subject:* Re: [Ifeffit] Linear Combination Fitting using ATHENA > >

Re: [Ifeffit] Linear Combination Fitting using ATHENA

mam - Original Message - From: Teck Kwang Choo To: XAFS Analysis using Ifeffit Sent: Tuesday, August 13, 2013 9:20 PM Subject: Re: [Ifeffit] Linear Combination Fitting using ATHENA Also Matthew, I have found that my sample spectrum is an almost exact replica of the magh

Re: [Ifeffit] Linear Combination Fitting using ATHENA

Sent: Tuesday, August 13, 2013 5:07 PM Subject: Re: [Ifeffit] Linear Combination Fitting using ATHENA Thanks Matthew for the spectra. Is it correct to use the spectra that was taken in transmission mode (the one you did) to fit those taken in fluorescence mode (my case)? Teck Kwang

Re: [Ifeffit] Linear Combination Fitting using ATHENA

Also Matthew, I have found that my sample spectrum is an almost exact replica of the maghemite spectrum, the only differences being the absorbance height of the edge-peak (highest peak), which is ok but more importantly I have found that there is a +1eV shift of my spectrum relative to the maghemit

Re: [Ifeffit] Linear Combination Fitting using ATHENA

Thanks Matthew for the spectra. Is it correct to use the spectra that was taken in transmission mode (the one you did) to fit those taken in fluorescence mode (my case)? Teck Kwang On 14 August 2013 01:37, Matthew Marcus wrote: > Here are reference spectra. The calibration is defined with th

Re: [Ifeffit] Linear Combination Fitting using ATHENA

Hi all! I am out of my place and I can not check it now, but I believe that in the database of XAFS (or something like that) there are some spectra of maghemites obtained by Lytle long time ago. Best regards Maria Elena Montero Cabrera El ago 13, 2013 3:38 a.m., "Teck Kwang Choo" escribió: > Hi

Re: [Ifeffit] Linear Combination Fitting using ATHENA

Here are reference spectra. The calibration is defined with the Fe metal edge at 7110.75eV. The maghemite spectrum has been corrected for mild overabsorption by reference to magnetite, which is very similar. The magnetite is synthetic Fe3O4 from Aldrich, and done in TEY, so no overabsorption.

Re: [Ifeffit] Linear Combination Fitting using ATHENA

Hi all, @Drew Latta: I was wondering why the end members should be magnetite and maghemite. Is it because they are both of inverse-spinel structure, the difference only being that the latter has all Fe completely oxidized into Fe(III)? Would you be able to provide the standard spectra to me if tha

Re: [Ifeffit] Linear Combination Fitting using ATHENA

t; http://www.mesg.anl.gov --- From: ifeffit-boun...@millenia.cars.aps.anl.gov [mailto:ifeffit-boun...@millenia.cars.aps.anl.gov] On Behalf Of Alexandre dos Santos Anastacio Sent: Monday, August 12, 2013 9:01 AM To: XAFS Analysis using Ifeffit Subject: Re: [Ifeffit] Linear Combination F

Re: [Ifeffit] Linear Combination Fitting using ATHENA

Hello, maybe that fingerprinting technique would be Mossbauer spectroscopy. The Fe(II)/Fe(III) ratio comes easily and also there are lots of papers about Mg-ferrite, an example: 10.1109/TMAG.2009.2018880 Alexandre. ___

Re: [Ifeffit] Linear Combination Fitting using ATHENA

That's magnetite unfortunately! On 12 August 2013 14:02, Scott Calvin wrote: > Yes it does, Teck Kwang: > http://millenia.cars.aps.anl.gov/cgi-bin/newville/Model-Search.cgi/ModelData/fe3o4_rt01_mar02.xmu > > --Scott Calvin > Sarah Lawrence College > > On Aug 11, 2013, at 11:12 PM, Teck Kwang Ch

Re: [Ifeffit] Linear Combination Fitting using ATHENA

The database: http://cars.uchicago.edu/~newville/ModelLib/search.html does not seem to have Ferrite. The matrix of my sample is largely Mg-ferrite where Fe is in the form of Fe (III). If you anyone has the spectra for Mg-ferrite, would it be possible to provide it to me? Otherwise, I do not think

Re: [Ifeffit] Linear Combination Fitting using ATHENA

Thanks for your reply Edmund. I agree with you that I might have not chosen the right standards for my sample. In fact, XRD analysis have confirmed that Ferrite is the main form of Fe in my sample but I did not have any ferrite standards during XANES analysis. Was wondering if you happen to have a

Re: [Ifeffit] Linear Combination Fitting using ATHENA

Dear Teck Kwang Choo, it is the ratio of the number of (in your case) iron atoms. This ratio has no unit. You will therefore get the same number if you calculate molar % ratio or weight % (Except you consider the weight of the missing electron in Fe3+... :-). Now, if you weigh your standards and w

[Ifeffit] Linear Combination Fitting using ATHENA

Hello, I have been using ATHENA to perform Linear Combination Fitting (LCF) on my XANES spectrum to quantify the amounts of Fe (II) and Fe (III) in my samples using only FeO and Fe2O3 as standards. The results showed a majority of Fe (II), which is contrary to what was expected. This made me wond