-----Original Message----- From: ifeffit-bounces@millenia.cars.aps.anl.gov [mailto:ifeffit- bounces@millenia.cars.aps.anl.gov] On Behalf Of Bruce Ravel Sent: Wednesday, January 26, 2005 1:30 PM To: asg2@lehigh.edu; XAFS Analysis using Ifeffit Subject: Re: [Ifeffit] Two edge problem (in the same scan)

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Hello everybody, I have a question/problem. Last year during the EXAFS course at NSLS, I had requested Bruce if it is possible to analyze the data with two edges. For example, I have the data for As and Se K-edges, which I collect in the same scan. In WinXAS program, I can section the edges and analyze them separately. At that time, the program was not able to perform these edges or the sectioning. Have we reached this

possibility.

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I tried again using the latest updated Athena, but it seems not to be working. Can you please tell me whether the sectioning or dealing with two edges in the same spectra can be done

I don't unfderstand why "sectioning" is necessary. What precludes you from reading the data set a second time and setting e0 to be appropriate for the second edge? Then your pre- and post-edge lines will be made using the second e0 and everything else should just follow normally.

I understand that Athena does not have a way to specify the second edge in the column selection dialog, but that seems to me like an inconvenience more than a real limitation. It is an inconvenience because you then have to specify the second e0 by hand rather than have Athena's magic find it for you, but is that really so hard?

B

[Kelly, Shelly D.] Another feature that I have found useful for data with multiple edges is the truncate function. Once you read the data set into Arthena. Make a copy of the data set. Choose your e-zero for each data set. And then truncate the data sets to the "normal" range. This will help with some of the automatic presets, which use the full data range by default, and can give you a very scary initial background function. SK