Donna (and anyone else who wonders about this), In gsas\examples there is an iparm file (inst_xry.prm) that can be used for most any Bragg-Brentano powder diffractometer. These instruments all perform more or less equally independent of manufacturer with respect to the things of interest for Rietveld refinement. If after doing a calibration with some sharp standard material you think you ought to change some of the default parameters the following records in the iparm file might be changed.
INS 1 IRAD 3 This record determines the choice of standard wavelength for selecting f' and f" for each atom type to be used in structure factor calculations. IRAD=3 is for CuKa radiation. INS 1 ICONS 1.540500 1.544300 0.0 0 0.7 0 0.5 This record contains the Ka1 and Ka2 wavelengths, zero point, polarization & Ka2/Ka1 ratio. If just using CuKa you may only need to change the polarization coefficient (0.7 in this example). It can be refined for a standard with reasonably known atom thermal motion parameters and a wide 2-theta scan. Align your diffractometer so ZERO=0; any peak offsets you may see are due to sample displacement not zero offset. INS 1PRCF1 2 6 0.01 INS 1PRCF11 2.000000E+00 -2.000000E+00 5.000000E+00 0.100000E+01 INS 1PRCF12 0.100000E+01 0.000000E+00 These records select the default profile function and values. The GU, GV and GW values are typical for most Bragg-Brentano diffractometers. Your sample will probably broaden the lines (LX, LY, etc.) so much that any attempt to vary the Gaussian coefficients will yield nonsense. Look in the GSAS Manual for details of the formats of these records and do the examples before you start on your own stuff. Bob Von Dreele -----Original Message----- From: Donna Arnold [mailto:[EMAIL PROTECTED] Sent: Thu 3/18/2004 4:32 AM To: [EMAIL PROTECTED] Hi! I am trying to refine some XRD data using GSAS and looking for an instrument parameter file for the Rigaku Dmax 2000 x-ray diffractometer. Can anyone help? Thanks Donna
