[Ifeffit] problem with E0 (enot) parameters

[Frenkel, Anatoly]

Just a comment, to add some sanity in this discussion:
 
FEFF6 is overestimating delta E0 for Pt and a few other metals. I forgot the reason but it could be the cause of a problem.
I think FEFF8 is doing a better job. Fortunately - and it was checked - no other problems occur, just E0 values change, when one usees FEFF8 instead of FEFF6 in most cases.
 
Anatoly
 

________________________________

From: ifeffit-bounces at millenia.cars.aps.anl.gov on behalf of Kropf, Arthur Jeremy
Sent: Fri 6/19/2009 3:41 PM
To: XAFS Analysis using Ifeffit
Subject: Re: [Ifeffit] problem with E0 (enot) parameters



With the very strong white lines at the L3 edges of oxidized Pt, W, Ir,
etc., there is no reason to assume that Eo is on the lower energy side
of the peak.

Jeremy Kropf

> -----Original Message-----
> From: ifeffit-bounces at millenia.cars.aps.anl.gov
> [mailto:ifeffit-bounces at millenia.cars.aps.anl.gov] On Behalf
> Of Zajac, Dariusz A.
> Sent: Friday, June 19, 2009 9:45 AM
> To: XAFS Analysis using Ifeffit
> Subject: Re: [Ifeffit] problem with E0 (enot) parameters
>
> Hi Scott,
> I am afraid that E0 jumps over the edge - see bmp's in the
> attachment (files with enot_12 means E0=12...). Hovewer 12 eV
> is still less than
> k=3 (the starting k value). Can it influence? I did also once
> more fit with R from 1.7 to 4A. Fits of first 2 peaks are
> identical - you can see in the attachment too...
> I hope you and anyone from the mailing list don't mind that I
> am attaching so many files...
>
> cheers
> darek
>
> >-----Original Message-----
> >From: ifeffit-bounces at millenia.cars.aps.anl.gov
> >[mailto:ifeffit-bounces at millenia.cars.aps.anl.gov] On Behalf
> Of Scott
> >Calvin
> >Sent: Friday, June 19, 2009 2:49 PM
> >To: XAFS Analysis using Ifeffit
> >Subject: Re: [Ifeffit] problem with E0 (enot) parameters
> >
> >
> >Hi Darek,
> >
> >OK, so if the K, H, and O don't affect the fit much for the C and N,
> >and the K, H, and O are returning nonsensical values, then a logical
> >possibility is that the E0's for C and N are correct. If you
> add 12 eV
> >to the E0 you chose in Athena, where in the spectrum does it
> fall? Is
> >it still before the white line? If so, it seems to me you
> don't have a
> >problem. If not, then we have to ponder further.
> >
> >--Scott Calvin
> >Sarah Lawrence College
> >
> >On Jun 19, 2009, at 8:28 AM, Zajac, Dariusz A. wrote:
> >
> >> Hi Scott,
> >> look also at H and O,
> >> but for me and for this fit important are only W-C and W-C-N
> >bondings.
> >> This sample is an reference sample for other cyano-brigded
> networks.
> >> So
> >> you suggest to focuse on K ions? how can it help with first
> >2 peaks? K
> >> is at ~5A.
> >> I have analysed in larger R space only to see how the
> >spectrum behave.
> >> contribution from K, O etc. at k highers than 5A is for me
> too low to
> >> analyse it resonable for such compound.
> >> I have attached in the previus post the last version of results. 
> >> Anyway,
> >> enots for C and N do not change if I am enlarging R region
> (when I am
> >> including next paths, also for K).
> >> about material I am quite sure ;) and crystal structure is from
> >> literature
> >>
> >> in the attachment you will find bmp file of the fit: data,
> fit, bkg
> >> and K path.
> >> fitting ranges k(3-15) R(1.7-6) dk 2 dr 0.5, phase
> correction - first
> >> C
> >>
> >> cheers
> >> darek
> >>
> >
> >_______________________________________________
> >Ifeffit mailing list
> >Ifeffit at millenia.cars.aps.anl.gov
> >http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit
> >
>

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