Hi Hashem, It is not the Rbkg you have to worry about in this case; it is the normalization. There are a couple of possibilities. One is that E0 is chosen very poorly for some reason. Check to make sure that E0 is in the rising portion of the edge. The other likely possibility is that either the pre-edge or post-edge lines are being poorly chosen. Click on those options under the plotting to see what those lines look like. If necessary change the pre-edge or normalization ranges to get them straightened out. --Scott Calvin Sarah Lawrence College On Aug 25, 2008, at 11:23 AM, Hashem Stietiya wrote:

Dear Dr. Ravel,

I am trying to optimize background removal of my spectra by setting the Rbkg to half the distance of the first shell peak. However, when I import my spectra in ATHENA, I notice that the edge step is a very large number and when converting to R space there are no well defined peaks. If I click on ‘fix step’, the R space becomes comprehendible and peaks appear. Do I continue using the ‘fix step’ and then setting Rbkg to half the distance of the first shell peak?

I appreciate your help.