[Ifeffit] Regarding XANES spectra of Manganese oxides

Thu Jun 17 20:46:56 CDT 2004

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 at millenia.cars.aps.anl.gov wrote:

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> Today's Topics:
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>    1. Re: a few words... (scalvin at 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)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Thu, 17 Jun 2004 14:01:28 -0400 (EDT)
> From: scalvin at slc.edu
> Subject: Re: [Ifeffit] a few words...
> To: ravel at phys.washington.edu,	"XAFS Analysis using Ifeffit"
> 	<ifeffit at millenia.cars.aps.anl.gov>
> Message-ID: <2823.138.110.111.207.1087495288.squirrel at 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
>
>
> ------------------------------
>
> Message: 2
> Date: Thu, 17 Jun 2004 14:17:38 -0500
> From: "Ahmed M Shahin" <shahin at umr.edu>
> Subject: [Ifeffit] A very quick question
> To: <Ifeffit at millenia.cars.aps.anl.gov>
> Message-ID: <001a01c4549f$c0ece3a0$fc689783 at 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
>
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> Message: 3
> Date: Thu, 17 Jun 2004 15:47:05 -0400
> From: Bruce Ravel <ravel at phys.washington.edu>
> Subject: Re: [Ifeffit] A very quick question
> To: XAFS Analysis using Ifeffit <ifeffit at millenia.cars.aps.anl.gov>
> Message-ID: <200406171547.05092.ravel at phys.washington.edu>
> Content-Type: text/plain;  charset="iso-8859-1"
>
> On Thursday 17 June 2004 03:17 pm, Ahmed M Shahin wrote:
> AM> Hello, I would like to ask a very quick question and I would
> AM> appreciate if someone can help me.  While running XANES fitting
> AM> for mixed valence state metals such as cerium (3/4), should I use
> AM> two arctangent functions with selected group of Lorentzian
> AM> functions or I have to use only one arctangent function with a
> AM> group of Gaussian functions?  I would appreciate if someone give
> AM> some advice.  Yours, Ahmed
>
> The most recent version of Athena allows you to use most any
> combination of arctangents and peak functions.  There are those that
> say using two arctangents is a good idea for a sample such as yours.
>
> I would recommend trying various different ways of simulating/fitting
> the data with lineshapes and find the combination that best describes
> all your data.  Since these lineshape fits are, at best, somewhat
> heuristic, I think the most important thing is that you treat all of
> your data in a *consistent* manner so that the trends in the data are
> consistent and intepretable in a consistent manner.
>
> A caveat -- I have not tested the peak fitting routine in Athena
> extensively in any case and certainly not in fits involving two
> arctangent functions.  I put in the ability to do two or more
> arctangents at Dave Barton's request.  I was kind of hoping that he
> would try it out and, as he has so often in the past, let me know if
> anything is wrong. Perhaps Dave has a comment? ;-)
>
> B
>
> --
>  Bruce Ravel  ----------------------------------- ravel at phys.washington.edu
>  Code 6134, Building 3, Room 405
>  Naval Research Laboratory                          phone: (1) 202 767 2268
>  Washington DC 20375, USA                             fax: (1) 202 767 4642
>
>  NRL Synchrotron Radiation Consortium (NRL-SRC)
>  Beamlines X11a, X11b, X23b
>  National Synchrotron Light Source
>  Brookhaven National Laboratory, Upton, NY 11973
>
>  My homepage:    http://feff.phys.washington.edu/~ravel
>  EXAFS software: http://feff.phys.washington.edu/~ravel/software/exafs/
>
>
>
> ------------------------------
>
> Message: 4
> Date: Fri, 18 Jun 2004 08:49:47 +0900
> From: "Gang Ho Lee" <ghlee at bh.knu.ac.kr>
> Subject: [Ifeffit] Reagrding Xanes spectra of manganese oxides
> To: <ifeffit at millenia.cars.aps.anl.gov>
> Message-ID: <PBENKJPJHOHCEKOMFOFAOEGBCBAA.ghlee at bh.knu.ac.kr>
> Content-Type: text/plain; charset="ks_c_5601-1987"
>
> Dear Sirs
>
> I am writing to you because we are not familiar with xanes.   We took xanes spectra of both sample (synthesized by us and we think it as gamma-Mn2O3 ) and Mn3O4 (reference) to make sure that we synthesized gamma-Mn2O3 nanoparticles.  The particle diameters ranged from 10 to 15 nm.  By using XRD pattern, the structure of sample was determined to be tetragonal with lattice constants of a=5.79 A and c=9.4 A, similar to Mn3O4.  From the XRD patterns, we can not distinguish between gamma-Mn2O3 and Mn3O4 because both show nearly identical XRD patterns (JACS 72, 856 (1950)).
>
> We attached a data file.  Could you please tell us whether the sample is gamma-Mn2O3 nanoparticles or not.
>
> Sincerely,
>
> Prof. Gang Ho Lee
> Department of Chemistry
> College of Natural Sciences
> Kyungpook National University
> Taegu 702-701, South Korea
> tel: 001-82-53-950-5340
> fax: 001-82-53-950-6330
> e-mail: ghlee at bh.knu.ac.kr
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