Re: [Ifeffit] EXAFS data

Hi Abhijeet: The Farrel Lytle data is in the form of staps with calibration points. You need to make a conversion to energy. Grant Bunker sent me this description a while ago. I have written a Python program to do the conversion but have had no time to finish it off and make it really useful. Hope this helps carlo --------------------------------------------------------------

From bunker@iit.edu Wed Aug 6 12:27:28 2008 Date: Wed, 6 Aug 2008 12:27:13 -0500 From: grant bunker To: segre@agni.phys.iit.edu Subject: Re: Lytle database

I wrote a little conversion program in mathematica for somebody who asked a year or so ago. It should be easy to pythonize it. The main thing to remember is the first column is in motor steps (!), and the angle is a linear function of motor steps, and the rest is just Bragg's law. Things are referenced physically to the copper edge. Key parameters used in the data acquisition program are in the header: dspace is obvious, stepdeg is steps per degree in the mono, cuedge is the position of the Cu edge as measured in motor step units. So, the business end of the conversion is something like this: (*constants*) hc=12398.5; Cuenrg=8980.3; (* these things should be extracted from file header *) dspace=3.13562; cuedge=50880.; stpdeg=4000.; (* code*) const=hc/(2*dspace); thetaCu=ArcSin[const/Cuenrg]; theta[n_]:=(n-cuedge)/stpdeg*pi/180.+thetaCu e[n_]:=const/Sin[theta[n]] I'm not positive, but I think the channel offsets are already subtracted from the other columns; the offsets are just listed for documentation. ---------------------------------------------------------- On Wed, 28 Jan 2009, abhijeet gaur wrote:

Hi We have Farell Lytle type data. When we put that into ATHENA we get the Energy curve. But we are not able to extract that Energy converted data from ATHENA . We tried to import the data in ORIGIN but we could not do so though the graph was imported.So if there is any way to extract the data please let us know.

Thanks

Abhijeet

-- Carlo U. Segre -- Professor of Physics Associate Dean for Special Projects, Graduate College Illinois Institute of Technology Voice: 312.567.3498 Fax: 312.567.3494 segre@iit.edu http://www.iit.edu/~segre segre@debian.org