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<DIV dir=ltr align=left><FONT color=#0000ff size=2 face=Arial><SPAN
class=967133413-14072010>Abhijeet,</SPAN></FONT></DIV>
<DIV dir=ltr align=left><FONT color=#0000ff size=2 face=Arial><SPAN
class=967133413-14072010></SPAN></FONT> </DIV>
<DIV dir=ltr align=left><FONT color=#0000ff size=2 face=Arial><SPAN
class=967133413-14072010>Consider the energy resolution of the dispersive EXAFS
beamline. A poor energy resolution could suppress the low-k amplitude
causing the Debye-Waller factor to compensate by being articifically low.
However, you also have an amplitude larger than 1. Adding an Ei component
will address the problem of poor energy resolution, but I would suggest that it
should be based on the measured energy resolution rather than being a "guessed"
variable. You can also measure the appropriate Ei using a known sample,
such as a copper foil for which you have comparable spectra on a beamline with
better energy resolution.</SPAN></FONT></DIV>
<DIV dir=ltr align=left><FONT color=#0000ff size=2 face=Arial><SPAN
class=967133413-14072010></SPAN></FONT> </DIV>
<DIV dir=ltr align=left><FONT color=#0000ff size=2 face=Arial><SPAN
class=967133413-14072010>What scattering paths and at what bond lengths are
responsible for the peak below 1 angstrom? It seems unlikely to me that a
Cu-O or Cu-N path would produce such a peak. These peaks would more
typically be closer to 1.5 angstroms.</SPAN></FONT></DIV>
<DIV dir=ltr align=left><FONT color=#0000ff size=2 face=Arial><SPAN
class=967133413-14072010></SPAN></FONT> </DIV>
<DIV dir=ltr align=left><FONT color=#0000ff size=2 face=Arial><SPAN
class=967133413-14072010>Jeremy Kropf</SPAN></FONT></DIV>
<DIV dir=ltr align=left><FONT color=#0000ff size=2 face=Arial><SPAN
class=967133413-14072010></SPAN></FONT> </DIV>
<DIV dir=ltr align=left><FONT color=#0000ff size=2 face=Arial><SPAN
class=967133413-14072010>Chemical Sciences and Engineering
Division</SPAN></FONT></DIV>
<DIV dir=ltr align=left><FONT color=#0000ff size=2 face=Arial><SPAN
class=967133413-14072010>Argonne National Laboratory</SPAN></FONT></DIV>
<DIV dir=ltr align=left><FONT color=#0000ff size=2 face=Arial><SPAN
class=967133413-14072010>Argonne, IL </SPAN></FONT></DIV><BR>
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<FONT size=2 face=Tahoma><B>From:</B>
ifeffit-bounces@millenia.cars.aps.anl.gov
[mailto:ifeffit-bounces@millenia.cars.aps.anl.gov] <B>On Behalf Of
</B>Abhijeet Gaur<BR><B>Sent:</B> Wednesday, July 14, 2010 2:00
AM<BR><B>To:</B> ifeffit<BR><B>Subject:</B> [Ifeffit] Negative ss
problem<BR></FONT><BR></DIV>
<DIV></DIV>
<DIV>Hi all,</DIV>
<DIV> I read the
discussion on negative Debye waller factor. As per the discussion the negative
value of this factor shows that the model has shortcomings, so it should be
corrected.</DIV>
<DIV> I am also getting the
same problem while fitting one of my samples. It is a Cu complex whose EXAFS
data is taken at Dispersive EXAFS beamline at RRCAT, Indore, India. </DIV>
<DIV> In the complex the
nearest neighbours of Copper atom are Nitrogen and Oxygen.</DIV>
<DIV> I am getting a very good fit
upto 3rd shell but the problem is that all ss parameters are coming negative.
I checked the model it seem correct.</DIV>
<DIV> Also I am getting a peak
below 1 Angs which is also getting fitted but I am not able to get that
whether it is a real or due to some noise. </DIV>
<DIV> I am attaching herewith the
results of data analysis and fitting. </DIV>
<DIV> Thanks in advance</DIV>
<DIV> With regards</DIV>
<DIV> Abhijeet Gaur</DIV>
<DIV>Vikram University</DIV>
<DIV>Ujjain, INDIA</DIV></BLOCKQUOTE></BODY></HTML>