On Monday 22 June 2009 09:24:32 am Eugenio Otal wrote:

I am looking for some small differences in XANES spectra and want to know how to set the edge step to a "right" value. The differences are around 2 eV shift and a change in the edge step is critical.

Eugenio, I am afraid that the question, as posed, is somewhat unanswerable. Careful alignment (preferably to a reference) is essential and you should take care to use the same parameters for every data set. I don't know how to advise you about "rightness", but consistency is certainly a must-do. If you are looking at subtle changes in the XANES features, you might consider turning off the "flattening" display trick that Athena uses for displaying XANES data. HTH, 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/