Hi Joseph: On Mon, 7 Jul 2008, Joseph Washington wrote:
Greetings all, I am an APS user and a graduate of XAFS Summer School - class of 2007 :) We have been doing EXAFS analysis on Ge[2]Sb[2]Te[x] thin films. I noticed that at the Ge edge in particular, the k-weight value used in the background removal cannot equal 3, or else the background function no longer follows the data and oscillates wildly and/or it shoots up at the edge energy dominating the plot window. Values of 1 and 2 work fine. Even more puzzling is that this problem is inherent for the Ge edge of data taken over numerous runs, and for various samples (GST-224, GST-225, 226, 227).
COuld you tell us why you would like to use a k-weight of 3 in the background removal process? I find that 1 (or 2 sometimes) is sufficient to get a good result. I just checked on a recent data set and I agree that k-weight 1 nd 2 give nearly identical results but that k-weight 3 for the same parameters is slightly different. It would help a lot if you oculd send a project file for us to look at. Carlo -- 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