[Ifeffit] Regarding XANES spectra of Manganese oxides

This is in response to Prof. Gang Ho Lee's question. There is indeed a spinel form of Mn2O3 which is isostructural with Mn3O4, except (as I recall from twenty years ago) that the +2 and +3 ion populations are reversed (2/3 of the ions are in octahedral sites, and 1/3 in tetrahedral). So even though the average charge state is changed, the structure isn't. The XANES and XRD are virtually the same because the structures are virtually the same. grant bunker On Thu, 17 Jun 2004 ifeffit-request@millenia.cars.aps.anl.gov wrote:

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Today's Topics:

1. Re: a few words... (scalvin@slc.edu) 2. A very quick question (Ahmed M Shahin) 3. Re: A very quick question (Bruce Ravel) 4. Reagrding Xanes spectra of manganese oxides (Gang Ho Lee)

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Message: 1 Date: Thu, 17 Jun 2004 14:01:28 -0400 (EDT) From: scalvin@slc.edu Subject: Re: [Ifeffit] a few words... To: ravel@phys.washington.edu, "XAFS Analysis using Ifeffit" Message-ID: <2823.138.110.111.207.1087495288.squirrel@mail.slc.edu> Content-Type: text/plain;charset=iso-8859-1

Bruce said:

...

I also wanted to comment on a couple of things that made me laugh out loud. One was was Paul's comment to Chris Derr asking him to inform the list of the answer once he gets EXAFS all figured out. (Is it 42?)

Bruce! I'm shocked at you! Everyone knows that legitimate EXAFS results must always be reported with the uncertainty; the answer is actually 42 +/- pi.

--Scott Calvin Sarah Lawrence College

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Message: 2 Date: Thu, 17 Jun 2004 14:17:38 -0500 From: "Ahmed M Shahin" Subject: [Ifeffit] A very quick question To: Message-ID: <001a01c4549f$c0ece3a0$fc689783@chem.umr.edu> Content-Type: text/plain; charset="iso-8859-1"

Hello, I would like to ask a very quick question and I would appreciate if someone can help me. While running XANES fitting for mixed valence state metals such as cerium (3/4), should I use two arctangent functions with selected group of Lorentzian functions or I have to use only one arctangent function with a group of Gaussian functions? I would appreciate if someone give some advice. Yours, Ahmed