[Ifeffit] huge S02 value ??

Tue Apr 7 13:36:42 CDT 2009

Yes.  That is what I meant.  Nonetheless, it was worth checking, just in
case.

Jeremy

Chemical Sciences and Engineering Division
Argonne National Laboratory
Argonne, IL 60439

Ph: 630.252.9398
Fx: 630.252.9917
Email: kropf at anl.gov

> -----Original Message-----
> From: ifeffit-bounces at millenia.cars.aps.anl.gov 
> [mailto:ifeffit-bounces at millenia.cars.aps.anl.gov] On Behalf 
> Of mzhu at udel.edu
> Sent: Tuesday, April 07, 2009 1:21 PM
> To: XAFS Analysis using Ifeffit
> Subject: Re: [Ifeffit] huge S02 value ??
> 
> Hello Jeremy,
>   Thanks for your reply. Did you mean that the logrithum of 
> I0/I was not taken? I checked my spectra again and I am sure I did. 
> 
> Best wishes,
> 
> Mengqiang   
> 
> 
> 
> 
> 
> 
> -----------------------
> Mengqiang Zhu
> Ph.D Candidate
> Environmental Soil Chemistry
> Department of Plant and Soil Sciences
> University of Delaware
> 152 Townsend Hall
> Newark, DE 19716
> http://ag.udel.edu/soilchem/zhu.html 
> 
> 
> ---- Original message ----
> >Date: Mon, 6 Apr 2009 10:55:02 -0500
> >From: ifeffit-bounces at millenia.cars.aps.anl.gov (on behalf 
> of "Kropf, 
> >Arthur Jeremy" <kropf at anl.gov>)
> >Subject: Re: [Ifeffit] huge S02 value ??  
> >To: "XAFS Analysis using Ifeffit" 
> <ifeffit at millenia.cars.aps.anl.gov>, 
> >"XAFS Analysis using Ifeffit" <ifeffit at millenia.cars.aps.anl.gov>
> >
> >
> >If the amplitudes in chi(k) are different, I would suggest 
> that in the set with the larger amplitude the logarithm of 
> the ratio was not taken when importing the data.
> >
> >Jeremy
> >
> >-----Original Message-----
> >From: ifeffit-bounces at millenia.cars.aps.anl.gov on behalf of 
> Frenkel, 
> >Anatoly
> >Sent: Sun 4/5/2009 8:54 PM
> >To: XAFS Analysis using Ifeffit
> >Subject: RE: [Ifeffit] huge S02 value ??
> > 
> >Hi,
> >Very strange. Your data are indeed more intense in k-space 
> than mine, after they are perfectly aligned. Since you have 
> some systematic noise in the end of the k-range, I wonder if 
> you should be better off remeasuring this system, instead of 
> trying to brain storm why it gives high S02.
> > 
> >Of course, it could mean that my data are wrong and your are 
> right. But this is not easy to troubleshoot. If you are in 
> doubt, better to look at other comparisons, between reference 
> materials that you collected during the same run and those 
> that you had measured earlier.
> > 
> >Anatoly
> > 
> >
> >
> >  _____
> >
> >From: ifeffit-bounces at millenia.cars.aps.anl.gov on behalf of 
> >mzhu at udel.edu
> >Sent: Sun 4/5/2009 1:47 PM
> >To: XAFS Analysis using Ifeffit
> >Subject: Re: [Ifeffit] huge S02 value ??
> >
> >
> >
> >Hello Anatoly,
> >  The E0 I used for EXAFS extraction is 8344 ev, which is 
> located in the half of the edge jump. I tried a higher E0 as 
> you suggested, such as 8347 ev, but I still got a huge S02 
> value. In the attchment is the mu(E) and average data of Ni 
> solution. I very appreciate your help.
> >
> >Best wishes,
> >
> >Mengqiang Zhu
> >
> >
> >
> >
> >
> >
> >
> >-----------------------
> >Mengqiang Zhu
> >Ph.D Candidate
> >Environmental Soil Chemistry
> >Department of Plant and Soil Sciences
> >University of Delaware
> >152 Townsend Hall
> >Newark, DE 19716
> >http://ag.udel.edu/soilchem/zhu.html
> >
> >
> >---- Original message ----
> >>Date: Sun, 5 Apr 2009 12:44:13 -0400
> >>From: ifeffit-bounces at millenia.cars.aps.anl.gov (on behalf of 
> >>"Frenkel, Anatoly" <frenkel at bnl.gov>)
> >>Subject: Re: [Ifeffit] huge S02 value ?? 
> >>To: "XAFS Analysis using Ifeffit" 
> <ifeffit at millenia.cars.aps.anl.gov>, 
> >><ifeffit at millenia.cars.aps.anl.gov>
> >>
> >>Hi Mengqiang,
> >>
> >>I have done fits of aqueous solution of NiSO4 before and 
> obtained S02 of 0.8 for the octahedrally coordinated Ni-O 
> shell. You did not send the mu(E) data, just chi(k), so I was 
> not able to compare my and your raw data fully, just in 
> k-space. Here is what I found: my data is in perfect 
> agreement in k-space with yours, only if I move E0 down to 
> the pre-edge region, and I suspect, therefore, it is where 
> you chose your E0.
> >>
> >>As a result, the entire, very intense, main absorption peak 
> became a 
> >>part of your EXAFS, increasing the intensity of the k-space signal 
> >>(since it became the first half-cycle of the EXAFS 
> oscillation), and 
> >>thus you got such a large S02. If you move your E0 to half-the edge 
> >>jump, your result will be the same as mine, 0.8
> >>
> >>Let me know if it helped,
> >>Anatoly
> >>
> >>________________________________
> >>
> >>From: ifeffit-bounces at millenia.cars.aps.anl.gov on behalf of 
> >>mzhu at udel.edu
> >>Sent: Sat 4/4/2009 10:04 PM
> >>To: ifeffit at millenia.cars.aps.anl.gov
> >>Subject: [Ifeffit] huge S02 value ??
> >>
> >>
> >>
> >>Hello everyone,
> >>  I have been fitting EXAFS of NiSO4 aqueous solution. The 
> feff files were created from Ni(OH)2 using Feff7.00. During 
> the fitting, coordination number was fixed as 6. The S02 
> derived from fitting is 1.22. I tried other materials for 
> creating feff files, such as NiCO3 and NiPO4, and I got the 
> similar S02 values. I also tried Feff6, it did not result in 
> a reasonable S02 value, either.
> >>   Anyone can tell me why it led to such high S02 value? 
> The data file and feff input file (Feff 7) are attached. 
> >>   Thanks in advance.
> >>
> >>Best wishes,
> >>
> >>Mengqiang Zhu
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>-----------------------
> >>Mengqiang Zhu
> >>Ph.D Candidate
> >>Environmental Soil Chemistry
> >>Department of Plant and Soil Sciences
> >>University of Delaware
> >>152 Townsend Hall
> >>Newark, DE 19716
> >>http://ag.udel.edu/soilchem/zhu.html
> >>
> >>
> >>
> >>_______________________________________________
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> >>Ifeffit at millenia.cars.aps.anl.gov
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> >
> >
> >
> >
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