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<DIV><FONT face="Courier New" size=2>That depends on the way you did your
calibration. If it really matches, including the</FONT></DIV>
<DIV><FONT face="Courier New" size=2>pre-edge features, with a 1eV shift, then
that's what you probably have. Did you take</FONT></DIV>
<DIV><FONT face="Courier New" size=2>into account my calibration, which puts the
Fe K-edge at 7110.75eV? Some people use other</FONT></DIV>
<DIV><FONT face="Courier New" size=2>values like 7112eV.</FONT></DIV>
<DIV><FONT face="Courier New" size=2> mam</FONT></DIV>
<BLOCKQUOTE
style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><B>From:</B>
<A title=teck.kwang.choo@monash.edu
href="mailto:teck.kwang.choo@monash.edu">Teck Kwang Choo</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A
title=ifeffit@millenia.cars.aps.anl.gov
href="mailto:ifeffit@millenia.cars.aps.anl.gov">XAFS Analysis using
Ifeffit</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Tuesday, August 13, 2013 9:20
PM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re: [Ifeffit] Linear Combination
Fitting using ATHENA</DIV>
<DIV><BR></DIV>
<DIV dir=ltr>
<DIV>
<DIV>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<BR>I
have found that there is a +1eV shift of my spectrum relative to the maghemite
one, probably due to slight differences in beamline. Do you think it is
alright to make a +1 eV shift to the maghemite spectrum (or -1eV shift to my
sample spectrum)?<BR><BR></DIV>Thanks.<BR><BR></DIV>Kind regards.<BR><BR>Teck
Kwang<BR></DIV>
<DIV class=gmail_extra><BR><BR>
<DIV class=gmail_quote>On 14 August 2013 10:07, Teck Kwang Choo <SPAN
dir=ltr><<A href="mailto:teck.kwang.choo@monash.edu"
target=_blank>teck.kwang.choo@monash.edu</A>></SPAN> wrote:<BR>
<BLOCKQUOTE class=gmail_quote
style="PADDING-LEFT: 1ex; MARGIN: 0px 0px 0px 0.8ex; BORDER-LEFT: #ccc 1px solid">
<DIV dir=ltr>
<DIV>Thanks Matthew for the spectra.<BR><BR></DIV>
<DIV>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)?<SPAN
class=HOEnZb><FONT color=#888888><BR><BR></FONT></SPAN></DIV><SPAN
class=HOEnZb><FONT color=#888888>
<DIV>Teck Kwang<BR></DIV></FONT></SPAN></DIV>
<DIV class=HOEnZb>
<DIV class=h5>
<DIV class=gmail_extra><BR><BR>
<DIV class=gmail_quote>On 14 August 2013 01:37, Matthew Marcus <SPAN
dir=ltr><<A href="mailto:mamarcus@lbl.gov"
target=_blank>mamarcus@lbl.gov</A>></SPAN> wrote:<BR>
<BLOCKQUOTE class=gmail_quote
style="PADDING-LEFT: 1ex; MARGIN: 0px 0px 0px 0.8ex; BORDER-LEFT: #ccc 1px solid">Here
are reference spectra. The calibration is defined with the Fe metal
edge at 7110.75eV. The maghemite spectrum has been corrected for
mild<BR>overabsorption by reference to magnetite, which is very similar.
The magnetite is synthetic Fe3O4 from Aldrich, and done in TEY, so
no overabsorption.<BR>The maghemite is from oxidation of Fe oxide
nanoparticles and has been verified by XRD and comparison with the ETH
group's maghemite spectrum.<BR> mam
<DIV><BR><BR>On 8/13/2013 1:33 AM, Teck Kwang Choo wrote:<BR></DIV>
<BLOCKQUOTE class=gmail_quote
style="PADDING-LEFT: 1ex; MARGIN: 0px 0px 0px 0.8ex; BORDER-LEFT: #ccc 1px solid">
<DIV>Hi all,<BR><BR>@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 that is the case? Thanks very
much!<BR><BR>Previously I have only thought of using hematite
(alpha-Fe2O3) and FeO as end-members, both representing Fe(III) and
Fe(II) respectively without giving much thought to the structure Fe
takes. I also had my doubts using magnetite (Fe3O4) as a standard as it
is a mixture of both Fe (II) and Fe (III). But thanks to the insights
Drew has given, I now think I should take the Fe-coordination
environment into account with the use of magnetite and maghemite as
standards.<BR><BR>@Alexandre and Matthew: I have obtained Mossbauer
spectra of some of my samples but like Drew said, it is not
straightforward at this point in time. Will see what I can do with the
data I have!<BR><BR>Thanks for all your responses! It is greatly
appreciated! This forum has been more helpful than I
thought!<BR><BR>Teck Kwang<BR><BR><BR></DIV>
<DIV>On 13 August 2013 01:34, Matthew Marcus <<A
href="mailto:mamarcus@lbl.gov" target=_blank>mamarcus@lbl.gov</A>
<mailto:<A href="mailto:mamarcus@lbl.gov"
target=_blank>mamarcus@lbl.gov</A>>> wrote:<BR><BR>
While it's true that Mossbauer is the gold standard for Fe valence
determination, access to the technique isn't all that common, and I
don't know<BR> of any facility that can do it on a micro
scale. Is there one?<BR>
mam<BR><BR><BR> On 8/12/2013 7:01 AM, Alexandre dos
Santos Anastacio wrote:<BR><BR>
Hello,<BR><BR> 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:<BR><BR></DIV>
10.1109/TMAG.2009.2018880 <<A
href="http://dx.doi.org/10.1109/__TMAG.2009.2018880"
target=_blank>http://dx.doi.org/10.1109/__<U></U>TMAG.2009.2018880</A>
<<A href="http://dx.doi.org/10.1109/TMAG.2009.2018880"
target=_blank>http://dx.doi.org/10.1109/<U></U>TMAG.2009.2018880</A>>><BR><BR>
Alexandre.
<DIV><BR><BR><BR><BR><BR>
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<DIV><BR><BR><BR><BR><BR>--<BR>Teck Kwang Choo<BR>PhD
Student<BR>Department of Chemical Engineering<BR>Room 225, Building
36<BR>Monash University<BR>Mobile No.: 04-11489904<BR><BR><BR></DIV>
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clear=all><BR>-- <BR><SPAN
style="FONT-FAMILY: arial,helvetica,sans-serif">Teck Kwang
Choo</SPAN><BR>PhD Student<BR>Department of Chemical Engineering<BR>Room
225, Building 36<BR>Monash University<BR>Mobile No.:
04-11489904<BR></DIV></DIV></DIV></BLOCKQUOTE></DIV><BR><BR clear=all><BR>--
<BR><SPAN style="FONT-FAMILY: arial,helvetica,sans-serif">Teck Kwang
Choo</SPAN><BR>PhD Student<BR>Department of Chemical Engineering<BR>Room 225,
Building 36<BR>Monash University<BR>Mobile No.: 04-11489904<BR></DIV>
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