On Monday 25 August 2008 12:38:46 Kropf, Arthur Jeremy wrote:

I believe I've seen this one before.  Athena cuts all of the groups to the group with the shortest range.

The reason for that is that when you export using the "Save marked groups to a file" option, you are asking Athena to write several groups to a common x-axis. That is, the file will contain the energy (in the case of mu(E) or norm(E)) in the first column, followed by columns containing the data. In order to do that, Athena interpolates all data onto the energy grid of the first group. To avoid interpolation problems, Athena first computes the largest common range in energy of the marked groups. As a result, some groups might be truncated. As Jeremy suggests -- this is a feature, not a bug ;-) B -- Bruce Ravel ------------------------------------ bravel@bnl.gov National Institute of Standards and Technology Synchrotron Methods Group at NSLS --- Beamlines U7A, X24A, X23A2 Building 535A Upton NY, 11973 My homepage: http://xafs.org/BruceRavel EXAFS software: http://cars9.uchicago.edu/~ravel/software/exafs/

On Thursday 18 September 2008 15:45:35 Jenny Cai wrote:

Hi guys,

Could anyone tell me which software in Ifeffit package can do peak fitting like the one shown in the attached file?

Jenny, Those look like photo-emission spectroscopy data. Nothing in the Ifeffit package is written explicitly for XPS. That said, Ifeffit is quite capable of "peak fitting" -- i.e. fitting an arbitrary combination of line shapes to arbitrary data. That is exactly what Athena's peak fitting dialog does: http://cars9.uchicago.edu/~ravel/software/doc/Athena/html/analysis/peak.html You might even be able to coerce Athena to do that with XPS data, but I won't make any promises. You could certainly write little Ifeffit scripts to do that sort of peak fitting. B -- Bruce Ravel ------------------------------------ bravel@bnl.gov National Institute of Standards and Technology Synchrotron Methods Group at NSLS --- Beamlines U7A, X24A, X23A2 Building 535A Upton NY, 11973 My homepage: http://xafs.org/BruceRavel EXAFS software: http://cars9.uchicago.edu/~ravel/software/exafs/

Hi Jenny, As Bruce pointed out, Ifeffit can fit such peaks, as can many other programs. The issues I'd be most concerned with would be the same using Ifeffit or something else, and are a) how to model the background of the spectra you showed: it doesn't look especially simple. You could include a constant and a very broad arctangent function for the background, or perhaps a polynomial. I think that Athena's "Fit Peak" screen does not have an option for all this, but it can be done with an Ifeffit script. b) how to set (and constrain?) the various centroids and widths of the peak basis functions. This is notoriously tricky, especially with the overlapping sub-peaks in the spectra you showed. My experience is that fixing the centroid energies of peak functions and letting the amplitudes vary is the most robust approach. Hope that helps, --Matt On Thu, Sep 18, 2008 at 2:45 PM, Jenny Cai wrote:

Hi guys,

Could anyone tell me which software in Ifeffit package can do peak fitting like the one shown in the attached file?

Thank you in advance!

Jenny Cai

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Thank you, guys!  - Jenny --- On Thu, 9/18/08, Matt Newville wrote: From: Matt Newville Subject: Re: [Ifeffit] XANES peak fitting To: "XAFS Analysis using Ifeffit" Received: Thursday, September 18, 2008, 5:50 PM Just a short follow up on this and the "bug of the month": In the current version of Athena, the "Plot Components" and "Plot Difference" checkboxes on the Peak Fitting Page triggers a similar "fatal" error to the Ifeffit-Athena connection that effectively hangs the session. For now, a possible work-around is to open the "Display Ifeffit buffer" window and repeatedly type ")" until the window becomes responsive. I'll work on setting up PerlApp to rebuild athena for windows, but it may take me a while to get a working version. --Matt _______________________________________________ Ifeffit mailing list Ifeffit@millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit __________________________________________________________________ Connect with friends from any web browser - no download required. Try the new Yahoo! Canada Messenger for the Web BETA at http://ca.messenger.yahoo.com/webmessengerpromo.php