absortion correction

[Peter Zavalij]

There are several function in GSAS for absorption correction. For Bragg-Brentano geometry the best is Suorti (#3). This correction (coeff.1 & Coeff.2 in range of .2-.5) is designed primarily for porosity correction but is does good job with absorption correction and any other correction that has 2th dependence, e.g. when incident beam is broader than the sample at lower angles. Note that absorption correction in Bragg-Brentano geometry makes sense only when relatively low absorbing sample is relatively thin. The necessity to perform absorption (not any other) correction can be estimated using the sample thickness and liner absorption coefficient, and of course some reasonable packing density. Regards, Dr. Peter Y. Zavalij  Director, X-ray Crystallographic Laboratory Department of Chemistry & Biochemistry 0107 Chemistry Building University of Maryland College Park, MD 20742-4454 Phone: (301)405-1861 Fax:   (301)314-9121 E-mail: [EMAIL PROTECTED] From: Gerard, Garcia S [mailto:[EMAIL PROTECTED] Sent: Friday, April 08, 2005 5:03 AM To: rietveld_l@ill.fr; [EMAIL PROTECTED] Subject: absortion correction   Dear everybody, How can i correct my sample's absortion with GSAS?   Thanks for your gentle answers in advance