[Ifeffit] Ifeffit Digest, Vol 104, Issue 4
Soham Mukherjee
soham.chem at gmail.com
Thu Oct 6 02:33:16 CDT 2011
Dear Ifeffit Community,
The attachment didn't open ?! I am resending the same.
In any case, I will give all the details :-
The sample is a thin layer, it's pretty homogeneous and had no pinholes
during measurements. The fit details are :-
k_min = 2, k_max = 14
R_min = 1, R_max = 3
The potential is self consistent in these calculations
Fitting was performed in the R-space
Best regards,
Soham.
On Thu, Oct 6, 2011 at 12:50 PM,
<ifeffit-request at millenia.cars.aps.anl.gov>wrote:
> Send Ifeffit mailing list submissions to
> ifeffit at millenia.cars.aps.anl.gov
>
> To subscribe or unsubscribe via the World Wide Web, visit
> http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit
> or, via email, send a message with subject or body 'help' to
> ifeffit-request at millenia.cars.aps.anl.gov
>
> You can reach the person managing the list at
> ifeffit-owner at millenia.cars.aps.anl.gov
>
> When replying, please edit your Subject line so it is more specific
> than "Re: Contents of Ifeffit digest..."
>
>
> Today's Topics:
>
> 1. Re: Energy shift (Dr. Dariusz A. Zaj?c)
> 2. Zinc Sulfide fitting (Soham Mukherjee)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Thu, 06 Oct 2011 08:45:05 +0200
> From: "Dr. Dariusz A. Zaj?c" <kicaj at ifj.edu.pl>
> To: XAFS Analysis using Ifeffit <ifeffit at millenia.cars.aps.anl.gov>
> Subject: Re: [Ifeffit] Energy shift
> Message-ID: <4E8D4E71.2000309 at ifj.edu.pl>
> Content-Type: text/plain; charset="utf-8"; Format="flowed"
>
> Your attachment do not help in this case...
> Do you know something more about sample? I suppose it is a thin layer.
> Have you checked if you have no defects, vacancies, etc?
> I suppose that you can follow instructions given in this post
> http://millenia.cars.aps.anl.gov/pipermail/ifeffit/2009-January/008522.html
> but you can be also interested in this topic:
> http://millenia.cars.aps.anl.gov/pipermail/ifeffit/2009-June/004293.html
> and especially in last posts.
> you can also try this suggestion
> http://millenia.cars.aps.anl.gov/pipermail/ifeffit/2010-June/009471.html
>
> In general - could you precise, what is k_{min} for your fit, and did
> you use self consistent potential in calculations?
>
>
>
>
>
> W dniu 11-10-06 02:28, JeongEunSuk pisze:
> > Thank Dariuz and Bruce.
> > TiO is deposited on Si substrate and PtO is fabricated on TiO2.
> > I measered EXAFS with Pt L3 edge(11563eV) and The model is decided
> > from FEFF8.0.
> > PtO has only fist shell like attached files So I chose the simple
> > model with octahedral structure (probe atom Pt, others O)
> > When the EXAFS was fitted by feffit, the variables were three eo(Enot
> > in Artemis, energy shift), do1(distance factor), sigo1(debye-waller
> > factor).
> > the results of fit is as following
> > variable best fit value uncertainty initial guess
> > eo = 19.283398 1.726426 0.000000
> > do1 = -0.023227 0.009557 0.096000
> > sigo1 = 0.003790 0.000583 0.003047
> > r-factor: 11
> > reduced-chi square: 95
> >
> > Energy shift by fit shows an amount of difference from Pt L3 edge. It
> > is my problem.
> > To reduce the energy shift, I tried to remove background carefully
> > again and to change distance Pt-O.
> > However the result was failed.
> >
> >
> >
> > ------------------------------------------------------------------------
> > Date: Wed, 5 Oct 2011 08:24:16 +0200
> > From: kicaj at ifj.edu.pl
> > To: ifeffit at millenia.cars.aps.anl.gov
> > Subject: Re: [Ifeffit] Energy shift
> >
> > Hi,
> > could say more precise what kind of energy shift you are talking
> > about? the position of the white line or the Enot in Artemis. How big
> > it is? Which version of Feff do you use? What do you mean writing
> > "removing background carefully"? Background in the EXAFS fit? Any
> > pictures to illustrate problem are welcome
> >
> > W dniu 11-10-05 03:25, JeongEunSuk pisze:
> >
> > Hell all
> > I have the study for PtO nanoparticles with EXAFS.
> > When I fitted the data to model, I had a problem for energy shift.
> > I thought that the energy shift obtained from fitting must be
> > below White line. However it was over white line.
> > Although I removed background carefully and changed bond length in
> > model, the energy shift was still big.
> > I want to know other factors which affect energy shift.
> >
> >
> > _______________________________________________
> > Ifeffit mailing list
> > Ifeffit at millenia.cars.aps.anl.gov <mailto:
> Ifeffit at millenia.cars.aps.anl.gov>
> > http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit
> >
> >
> > _______________________________________________ Ifeffit mailing list
> > Ifeffit at millenia.cars.aps.anl.gov
> > http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit
> >
> >
> > _______________________________________________
> > Ifeffit mailing list
> > Ifeffit at millenia.cars.aps.anl.gov
> > http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit
> -------------- next part --------------
> An HTML attachment was scrubbed...
> URL: <
> http://millenia.cars.aps.anl.gov/pipermail/ifeffit/attachments/20111006/907c019b/attachment-0001.htm
> >
>
> ------------------------------
>
> Message: 2
> Date: Thu, 6 Oct 2011 12:50:24 +0530
> From: Soham Mukherjee <soham.chem at gmail.com>
> To: ifeffit at millenia.cars.aps.anl.gov
> Subject: [Ifeffit] Zinc Sulfide fitting
> Message-ID:
> <CAH3zd5wQrqtkkML+vk8DsEcTbYn63SDuzTh-gssinJpVP2tJfQ at mail.gmail.com
> >
> Content-Type: text/plain; charset="iso-8859-1"
>
> Zinc Sulfide exists largely in two phases, either the cubic zinc-blende
> (F-43m) phase, or the hexagonal wurtzite (P63cm) phase.
>
> The details of the NN distances are as follows :-
> 1. For cubic phase, the NN distances (Zinc to Sulfur bond lengths) are
> 2.3028 Angstroms each, 4 such bonds exist in a tetrahedral arrangement;
> 2. For hexagonal phase, there are 2 different NN distances (Zinc to Sulfur
> bond lengths) 3 bonds having the length 2.3421 Angstroms each, and 1
> axially
> elongated bond of length 2.3465 Angstroms. So they differ only by 0.0044
> Angstroms !
>
> I am performing a first shell fit to Zinc Sulfide which exists in the
> wurtzite phase (hexagonal_P63cm). However, I could fit it quite well taking
> the cubic phase (Zinc blende_F-43m) as my starting model. The only thing is
> that since bond distances are higher in a hexagonal phase than the cubic
> phase, I end up with a considerable delr as I underestimated my starting
> bond length value. Taking a wurtzite model involves defining two different
> bond lengths (which differ only by 0.0044 Angstroms !), paths 1 and 2 in
> the
> FEFF, whose sigma^2 values are quite similar. This gives unusually large
> delr values and high sigma^2 for the longer axial bond, which looks
> suspicious !
>
> Do I really need to define the two bond distances separately of so close
> values? Or taking a cubic phase will be sufficient? Please find the
> attached
> project file (artemis.apj) where I have tried out some simulations with
> both
> cubic and hexagonal models.
>
>
> With best regards,
> Soham.
> -------------- next part --------------
> An HTML attachment was scrubbed...
> URL: <
> http://millenia.cars.aps.anl.gov/pipermail/ifeffit/attachments/20111006/67aeec95/attachment.htm
> >
> -------------- next part --------------
> A non-text attachment was scrubbed...
> Name: artemis.apj
> Type: application/octet-stream
> Size: 199478 bytes
> Desc: not available
> URL: <
> http://millenia.cars.aps.anl.gov/pipermail/ifeffit/attachments/20111006/67aeec95/attachment.obj
> >
>
> ------------------------------
>
> _______________________________________________
> Ifeffit mailing list
> Ifeffit at millenia.cars.aps.anl.gov
> http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit
>
>
> End of Ifeffit Digest, Vol 104, Issue 4
> ***************************************
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://millenia.cars.aps.anl.gov/pipermail/ifeffit/attachments/20111006/e391fa01/attachment.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: artemis.apj
Type: application/octet-stream
Size: 199478 bytes
Desc: not available
URL: <http://millenia.cars.aps.anl.gov/pipermail/ifeffit/attachments/20111006/e391fa01/attachment.obj>
More information about the Ifeffit
mailing list