Pei, The following page will help: http://cars9.uchicago.edu/~ravel/software/doc/Athena/html/bkg/rbkg.html I think what you are seeing is just effects of removing data that contributes to the mu(E) spectrum. As for why the feature (low-R junk) increases as Rbkg is adjusted from 1.0 to 1.21 but disappears at 1.22, I'm not sure but my guess is that this is an artifact of removing some of the data that contributes to the feature, and by 1.22 you have removed enough that the feature disappears (hopefully someone will correct me if I'm wrong). I would be weary of using an Rbkg of 1.22 though (as I think you see why in the plots - Question 3). Cheers, Richard
To Dear authors: We have a Rbkg question about Rutile, and in order to demonstrate these questions more clearly, we make it up on attach .ppt file, and thanks for your great helping before.
Pei
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