Example GSAS Energy Dispersive X-ray Diffraction files
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Hints and advice on using Energy Dispersive Diffraction Data with GSAS by Yusheng ZhaoDate: Mon, 30 Apr 2001 14:40:32 -0600 To: Lachlan Cranswick [lachlan@ldeo.columbia.edu] From: yzhao@lanl.gov (Yusheng Zhao) Subject: Le Bail refinement for EDX Dear Lachlan, The following are something I prepared for GSAS users who want to analyze their energy dispersive data. Hope it can help. ***************************************************** The general approach to refine energy dispersive x-ray diffraction data The GSAS package has a program called "x17bcnv.exe" which is used for converting the energy dispersive data "***.mca" collected at X17b, NSLS, to the GSAS format "***.dat". The GSAS formated data file will be recognized by current GSAS program. Presently, we use LeBail (not Rietveld) technique to refine the energy dispersive x-ray diffraction data, which ignores intesity information. Therefore, the GSAS can only refine peak positions and lattice constants, and no refinement on atomic positions. Multiple phase mixture can also be refined. We are working on the technique to refine structure using energy dispersive data. It is not ready yet. Attached are an original X17b data "jddi1004.mca" and the converted GSAS data "jddi1004.dat". Also attached is a instrument file for the energy dispersive data "inst_x17.prm". You should be able to figure out how to convert your data from there. The energy dispersive data of NSLS X17B (Stony Brook) format (jddi1004.mca) can be converted to GSAS format (jddi1004.dat) using the X17BCNV.EXE in GSAS/exe package. One may try to convert his/her file to NSLS X17B format first and then run X17BCNV.exe to make GSAS format. After the convertion, he/she needs to use "inst_x17.prm" as the parameter file for the input. ************************************** The header of "jddi1004.dat". jadeite ambient 1995: 2: 9: 7:46:58 5.85335 BANK 1 2047 205 EDS 1.44982E-01 6.16793E-02 -2.91062E-07 1.23442E-10 STD The 5.85335 is 2-theta for EDS data, only spaces after it in the first line. Second line has polunomial fit of channel(start from ch.0 up to ch.2047) to energy(KeV). Energy cal. parameter 1 0.14498218156313670E+00 Energy cal. parameter 2 0.61679316154140906E-01 Energy cal. parameter 3 -0.29106203137951869E-06 Energy cal. parameter 4 0.12344200227292932E-09 They are truncated to 5 digits after the decimal point in ".dat" ************************************** The instrument parameter file: "inst_x17.prm" 123456789012345678901234567890123456789012345678901234567890 INS BANK 1 INS 1 IRAD 0 INS HTYPE PXER (indicate Powder X-ray Energy Dispersive) INS 1 ICONS 5.8472 (indicate Two-Theta angle) INS 1I HEAD DUMMY INCIDENT SPECTRUM FOR EDS DIFFRACTOMETER INS 1I ITYP 0 0.0000 150.0000 1 INS 1PRCF1 1 4 0.01 INS 1PRCF11 0.173000E-03 -0.161000E-01 0.401000E+00 0.000000E+00 (indicate initial profile function) Inside GSAS, you need to turn on the LeBail switch following the steps: L - Least square refinement set up L - Edit least square controls E - Change poweder data Fobs extraxtion flags C - Change Fo extraction method flages & entering 1 for LeBail method. Best Regards. Yusheng Zhao. |
Using Energy Dispersive Diffraction Data with GSASVia Rietveld Mailing List
Date: Tue, 20 Jun 2000 16:38:37 -0400 To: [rietveld_l@ill.fr] Subject: Conversion from Synchrotron to GSAS Content-Disposition: inline Hi everybody, I have question regarding the synchrotron data. I'd like to convert the Energy Dispersive Data from Synchrotron to GSAS file. It composes of energy (keV) and intensity count. What program should I use? Can anybody help me? Regards, Walairat |
Subject: Re: Conversion from Synchrotron to GSAS To: rietveld_l@ill.fr Date: Wed, 21 Jun 2000 11:01:12 +0100 (BST) Precedence: list Reply-To: RIETVELD_L Distribution List [rietveld_l@ill.fr] > I have question regarding the synchrotron data. I'd like to >convert the Energy Dispersive Data from Synchrotron to GSAS >file. It composes of energy (keV) and intensity count. >What program should I use? Can anybody help me? > > Regards, > Walairat I would be interested in the procedure for GSAS to handle Energy Dispersive data in a native fashion. PowderX by Cheng Dong and Powder v 2.00 by Nita Dragoe can view, analyse and manipulate Energy Dispersive data in a native fashion. PowderX: http://www.ccp14.ac.uk/tutorial/powderx/ Powder v 2.00 Tutorial: http://www.ccp14.ac.uk/tutorial/powder/index.html Download: http://www.ccp14.ac.uk/ccp/web-mirrors/ndragoe/html/software.html ===== To trick other software into being able to use energy dispersive data - you could convert it into an angular dispersive equivalent - which in theory any common diffraction software could then use to a limited extent. DLConvert for Windows can do this on Daresbury SRS and Argonne format Energy Dispersive data. http://www.ccp14.ac.uk/projects/dl-conv/ The latest version has some minor bugs that a new student programmer will be fixing next month and the best version to get for the moment is 1.26: http://www.ccp14.ac.uk/projects/dl-conv/Dlconv1-26.exe It will also do interpolation of the data into constant steps when going from Channels/KeV to 2-theta format. Lachlan. -- Lachlan M. D. Cranswick Collaborative Computational Project No 14 (CCP14) for Single Crystal and Powder Diffraction Daresbury Laboratory, Warrington, WA4 4AD U.K Tel: +44-1925-603703 Fax: +44-1925-603124 E-mail: l.cranswick@dl.ac.uk Ext: 3703 Room C14 http://www.ccp14.ac.uk |
Date: Wed, 21 Jun 2000 09:11:01 -0600 To: RIETVELD_L Distribution List [rietveld_l@ill.fr] Subject: Re: Conversion from Synchrotron to GSAS Precedence: list Lachlan (and others), GSAS will handle "native" energy dispersive data just fine. The raw data is in the "standard" GSAS format (10 fields of 8 characters) with intensities measured in constant energy steps. The "BANK" record looks like the following: BANK 1 2047 205 EDS 1.67141E-01 6.13157E-02 4.89310E-08 -3.53527E-12 STD The four values after "EDS" are the coefficients for the equation E = c(1)+c(2)*s+c(3)*s^2+c(4)*s^3 that converts step number (s) to energy in keV. These coefficients must be determined for each instrument setup by calibration with a standard material. Changing 2theta for the detector will change these values. If the measured intensities are "precorrected" then the alternative "ESD" data format can be used instead. The instrument parameter file for EDS data looks like: 123456789012345678901234567890123456789012345678901234567890 NS BANK 1 INS 1 IRAD 0 INS HTYPE PXER NS 1 ICONS 7.81476 INS 1I HEAD DUMMY INCIDENT SPECTRUM FOR EDS DIFFRACTOMETER INS 1I ITYP 0 0.0000 150.0000 1 INS 1PRCF1 1 4 0.01 NS 1PRCF11 0.173000E-03 -0.161000E-01 0.401000E+00 0.000000E+00 A copy of this file is in the gsas distribution material as \gsas\example\inst_x17.prm. One should change the value on the "ICONS" record to what ever 2theta value the detector was positioned at for your experiment. Bob Von Dreele |