Hi Assuming your spectrum is calibrated and you know the "correct" E0 , you can use the following workaround to plot data on a (E-E0) axis: set the energy shift in Athena to "minus E0" and Athena's E0 to zero. Andreas ________________________________ Von: ifeffit-bounces@millenia.cars.aps.anl.gov im Auftrag von Barton, David (DG) Gesendet: Do 12.03.2009 17:31 An: XAFS Analysis using Ifeffit Betreff: Re: [Ifeffit] XANES Bruce, I believe what Aimee wants to see is E-Eo (eV) plotted on the x-axis instead of E (eV) in the Athena plot window. I don't think you have the option anywhere in Athena to plot the data like this. Aimee, Athena does let you easily export the data as an x-y dataset that can you put into your favorite plotting software and do the simple subtraction that you desire to plot. Dave -----Original Message----- From: ifeffit-bounces@millenia.cars.aps.anl.gov [mailto:ifeffit-bounces@millenia.cars.aps.anl.gov] On Behalf Of Bruce Ravel Sent: Thursday, March 12, 2009 9:11 AM To: XAFS Analysis using Ifeffit Subject: Re: [Ifeffit] XANES On Thursday 12 March 2009 08:24:44 am Aimee Morey wrote:

I have collected full XANES and EXAFS spectra. I have imported the full spectrum into Athena. I am now trying to analyze using XANES, but I am have trouble figuring out how to set an absolute energy, i.e. 7709 eV = 0 eV or such, and have the energy scaled negatively and positively. It is probably super simple, can anyone please help?

Hi Aimee, Data calibration is explained in the Athena User's Guide: http://cars9.uchicago.edu/~ravel/software/doc/Athena/html/process/cal.ht ml If that is too terse or does not address your question, you might consider making a small Athena project file which demonstrates what you are confused about and then post that to the mailing list. Posting data is usually the best way to get a concrete answer. 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/ _______________________________________________ Ifeffit mailing list Ifeffit@millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit _______________________________________________ Ifeffit mailing list Ifeffit@millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit

Aimee, It is possible, but probably not advisable to set the E-Eo before linear combination fitting. If you set Eo before fitting using the Eo that Athena reports (or any other method of estimating Eo) for each dataset you will probably be subtracting a different Eo from each XANES dataset. Then when you do the linear combination fitting each of the data sets are not on the same x-axis. Thanks to Bruce, he put in the ability to Fit Eo in the Linear combination fitting window which may correct for these differences that you imposed on your datasets, but why add complexity to your fitting. With that said if you picked a single Eo (say for the metal foil) and subtracted it from each dataset this would avoid the issue that I just described, however now you must be sure that each spectrum that you are using is calibrated because you have lost the ability to use the Calibration feature that Athena has built in by setting the "E Shift" to the same -Eo value for each dataset. This is why it would be advisable to set E-Eo after you have completed your linear combination fitting using the nice workaround that Andreas provided. Dave ________________________________ From: ifeffit-bounces@millenia.cars.aps.anl.gov [mailto:ifeffit-bounces@millenia.cars.aps.anl.gov] On Behalf Of Aimee Morey Sent: Thursday, March 12, 2009 3:07 PM To: XAFS Analysis using Ifeffit Subject: Re: [Ifeffit] XANES David, Scott and Andreas, Thanks you so much, that is exactly what I want to do. Another question before I get myself into trouble. Is it advisable to set E-Eo before or after I want to analyze with linear combinations? Or is either option viable? Aimee On Thu, Mar 12, 2009 at 12:55 PM, Voegelin, Andreas wrote: Hi Assuming your spectrum is calibrated and you know the "correct" E0 , you can use the following workaround to plot data on a (E-E0) axis: set the energy shift in Athena to "minus E0" and Athena's E0 to zero. Andreas ________________________________ Von: ifeffit-bounces@millenia.cars.aps.anl.gov im Auftrag von Barton, David (DG) Gesendet: Do 12.03.2009 17:31 An: XAFS Analysis using Ifeffit Betreff: Re: [Ifeffit] XANES Bruce, I believe what Aimee wants to see is E-Eo (eV) plotted on the x-axis instead of E (eV) in the Athena plot window. I don't think you have the option anywhere in Athena to plot the data like this. Aimee, Athena does let you easily export the data as an x-y dataset that can you put into your favorite plotting software and do the simple subtraction that you desire to plot. Dave -----Original Message----- From: ifeffit-bounces@millenia.cars.aps.anl.gov [mailto:ifeffit-bounces@millenia.cars.aps.anl.gov] On Behalf Of Bruce Ravel Sent: Thursday, March 12, 2009 9:11 AM To: XAFS Analysis using Ifeffit Subject: Re: [Ifeffit] XANES On Thursday 12 March 2009 08:24:44 am Aimee Morey wrote: > I have collected full XANES and EXAFS spectra. I have imported the full > spectrum into Athena. I am now trying to analyze using XANES, but I am > have trouble figuring out how to set an absolute energy, i.e. 7709 eV = 0 > eV or such, and have the energy scaled negatively and positively. It is > probably super simple, can anyone please help? Hi Aimee, Data calibration is explained in the Athena User's Guide: http://cars9.uchicago.edu/~ravel/software/doc/Athena/html/process/cal.ht ml <http://cars9.uchicago.edu/%7Eravel/software/doc/Athena/html/process/cal .ht%0Aml> If that is too terse or does not address your question, you might consider making a small Athena project file which demonstrates what you are confused about and then post that to the mailing list. Posting data is usually the best way to get a concrete answer. 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/ http://cars9.uchicago.edu/%7Eravel/software/exafs/ _______________________________________________ Ifeffit mailing list Ifeffit@millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit _______________________________________________ Ifeffit mailing list Ifeffit@millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit _______________________________________________ Ifeffit mailing list Ifeffit@millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit -- Aimee M. Morey Graduate Assistant Department of Chemistry, U-3060 University of Connecticut 55 North Eagleville Rd Storrs, CT 06269-3060 Phone # (860) 486 - 6567 Fax # (860) 486 - 2981