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hi,<br>
please don't think wrong about my question, but from my experience
sometimes problems are on the other side of analysis... Simply, I
want to be clearly sure what you did.<br>
as I understand: you aligned and calibrated spectra in Athena (by
reference sample) and than you imported the apj file to Artemis?
Then you fitted your experimental data to the model of the unit
cell? If you say "fitted E0 in Artemis" you mean usually named
"delE0" in path or "Enot" fitting parameter from "Guess, Def, Set"
window?<br>
I asked about changes of the set-up of beamline, simply because I
had met with such problems...<br>
kicaj<br>
<br>
<br>
<br>
W dniu 11-06-06 10:17, Brandon Reese pisze:
<blockquote
cite="mid:BANLkTin92MPAu=s4_wEBC7xMPTijumXjsQ@mail.gmail.com"
type="cite">Ahh, it sounds I wasn't entirely clear on what I
doing. The measurements were at the In edge, so I aligned all the
scans such that the peak in the first derivative of the reference
foil was at 27940 eV. The peak of the first derivative in the
samples was ~27944 eV. The 1st derivative peaks of samples grown
without additional oxygen ("conducting") compared to the samples
grown with additional oxygen ("intrinsic") were ~0.5 eV different
or less. <br>
<br>
Using the peak of the first derivative in Athena for the
background subtraction, the refined E0 in Artemis was ~7 eV for
conducting samples and ~5.5 eV for intrinsic samples. I also tried
setting the E0 in Athena to the peak of the whiteline, which was
about 27950 eV. Again the spread between the white line peak
values was ~0.5 eV between samples. With this value for the
background subtraction in Athena, Artemis refined the E0's to be
~1.5 eV for the conducting samples and ~0 eV for the intrinsic
samples.<br>
<br>
Another piece of information is that the refined CN's for the
samples had an inverse correlation to shift in E0. So the
conducting samples with a higher E0 (by 1.5 eV) had a lower CN of
about 0.1. The calculated correlation in Artemis for the two
variables was ~35%.<br>
<br>
I didn't intentionally change anything on the beamline setup. I
measured all of the conducting samples and then all of the
intrinsic samples. So if there was a sudden change in *something*
in between the sample groups, it would be consistent. The sample
changes took ~10 minutes at most, so the change would have to
happen on that time scale. The only other consistency I noticed is
the conducting samples had to be shifted ~0.7 eV to get the metal
foil to line up, and the intrinsic samples only had to be shifted
about 0.1 eV.<br>
<br>
Brandon<br>
<br>
<div class="gmail_quote">2011/6/6 "Dr. Dariusz A. Zając" <span
dir="ltr"><<a moz-do-not-send="true"
href="mailto:kicaj@ifj.edu.pl">kicaj@ifj.edu.pl</a>></span><br>
<blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt
0.8ex; border-left: 1px solid rgb(204, 204, 204);
padding-left: 1ex;">
<div bgcolor="#ffffff" text="#000000"> Hi Brandon,<br>
before someone gives you correct answer, could you shortly
inform us, what is the E0 for reference foil, for each
experimental data. As I understand you have a shift of 7eV
between samples, but measured on samples, thus would be nice
to see what is the shift for reference.<br>
The second question comes for me automatically - have you
done something with the beamline set-up between experiments
?<br>
kicaj<br>
<br>
W dniu 11-06-06 08:56, Brandon Reese pisze:
<blockquote type="cite">
<div>
<div class="h5">Hi all,<br>
<br>
I am looking at EXAFS of thin film metal oxides. I am
varying both metal content and the oxygen content of
the films. I aligned the scans with a metal reference
foil collected simultaneously. In Artemis, I have
noticed that when changing between films with no extra
oxygen versus those with extra oxygen there is a shift
in the fitted E0 of ~1.5 eV (after aligning to the
foil). I tried setting the E0 in Athena to the peak of
the 1st derivative and the peak of the white line with
the same result (~7 eV difference). I was a little
surprised by the offset because in Athena the E0
values varied by <0.5 eV. I am not sure if the
argument could be made that this shift is a result in
a changing oxidation state because it doesn't show up
in the XANES (at least qualitatively). Are there
other experimental effects that could cause a shift
like this, or is this likely something real in my
material? If anyone want to see a representative group
of data, let me know.<br>
<br>
I also have an unrelated quick (I think) question on
the EXAFS equation. In some references I see a term
1/(k R)^2 and in others it is 1/(k R^2). I couldn't
really see any reason for the difference, unless it is
to correct for subtle differences in how the other
terms are defined.<br>
<br>
Thanks<br>
Brandon<br>
</div>
</div>
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