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Dear James, Am 27.01.10 10:08, schrieb James Holton: <snip> > I'm still not really sure what the difference is between a Bragg spot > and a feature "under" it. Why not define a "Bragg intensity" > operationally? Subtracting local background with a least-squares > plane is pretty much universally done, and as long as the disorder is > uncorrelated, the intensities obtained this way really are those of > the partial-occupancy models we currently build. It is when this > assumption breaks down that we need a "correction factor". </snip> Since diffuse scattering leads to long tails around the Bragg spots, there was an interesting approach by Bob Blessing some time ago to fit a kind of triangular background under the (2D-)spots from an empirical least-squares analysis of the diffuse scattering in these long tails and subtract this background from the total intensities. To my knowledge, his approach hasn't gone into any data processing program (maybe in Bob Blessing's DREAR - but I don't use it). Here is the reference: "Data reduction and error analysis for accurate singel crystal diffraction intensities", Robert H. Blessing, Cryst. Rev., Vol. 1, pp 3-58 Best regards, Dirk. ******************************************************* Dirk Kostrewa Gene Center, A 5.07 Ludwig-Maximilians-University Feodor-Lynen-Str. 25 81377 Munich Germany Phone: +49-89-2180-76845 Fax: +49-89-2180-76999 E-mail: [log in to unmask] WWW: www.genzentrum.lmu.de *******************************************************