Good going Dave. I think that you are correct. Shelly

-----Original Message----- From: ifeffit-bounces@millenia.cars.aps.anl.gov [mailto:ifeffit- bounces@millenia.cars.aps.anl.gov] On Behalf Of Barton, David (DG) Sent: Thursday, January 11, 2007 10:49 AM To: 'XAFS Analysis using Ifeffit' Subject: RE: [Ifeffit] Projekt with the "flatten-problem"

Jens,

It appears to me that the E-shift is causing the problems with the step in the pre-edge data. Shelly's data only appears to remove the step because the pre-edge and the extrapolated post-edge plots are nearly parallel. If you adjust the Normalization range in Shelly's data you will see the step appear again.

However, if you set the E-shift to zero and reset Eo, pre-edge range, and normalization range (to your liking) you will see that the step is goes away. So the work around would be to subtract the E-shift from your Raw data, then import into Athena and do not use any E-shift.

Bruce or Matt may have to comment, but it appears to me that the normalization/flatten routine may not be dealing with the E-shift appropriately.

Dave

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-----Original Message----- From: ifeffit-bounces@millenia.cars.aps.anl.gov [mailto:ifeffit-bounces@millenia.cars.aps.anl.gov] On Behalf Of Kelly, Shelly D. Sent: Thursday, January 11, 2007 11:11 AM To: XAFS Analysis using Ifeffit Subject: RE: [Ifeffit] Projekt with the "flatten-problem"

Hi Jens,

I believe the problem is related to the structure in the data before E0. If you choose e0 to be at the beginning of the structure then the normalization is handled better by Athena. Take a look at the attached project file. The first data set with e0 on the edge as you would choose for EXAFS analysis (e1) shows the error that Jens reported. The second data set with a lower value for e0 at the beginning of the structure (e2) gets the job done.

Cheers, Shelly

--------------------------- Shelly Kelly Argonne National Laboratory Bldg 203, RM E113 9700 S. Cass Ave Argonne, IL 60439

Molecular Environmental Science Group www.mesg.anl.gov skelly@anl.gov phone: 630-252-7376

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-----Original Message----- From: ifeffit-bounces@millenia.cars.aps.anl.gov [mailto:ifeffit- bounces@millenia.cars.aps.anl.gov] On Behalf Of Jens Kruse Sent: Thursday, January 11, 2007 2:38 AM To: Athena mailing List Subject: [Ifeffit] Projekt with the "flatten-problem"

Hi,

find attached an example with the "flatten-problem". thanks a lot,

jens

"Hi,

I have a normalization problem with Athena. If I turn on the "flatten" option in the background removal section, Athena creates in some of the normalized spectra a step in the pre-edge range. How can I get rid of it?

Thanks,

jens"

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