INTRODUCTION XRDA was designed to simplify and speed the analysis of energy-dispersive X-ray diffraction data. It can also deal, to a lesser extent, with different data sets e.g. angle dispersive X-ray diffraction and light spectroscopic data. It runs under Microsoft Windows 3.1 or Windows 95. Preferrably, it may be transferred by anonymous ftp from "joule.physics.uottawa.ca" in /pub/lpsd/xrda. If you use a copy electronically transferred, make sure to e-send your e-mail address to "serge@physics.uottawa.ca", if you want to be notified of updates and patches. INSTALLATION Now a few words about the installation of XRDA on your hard disk. The enclosed 3-1/2"diskette (or ftp directory) contains all the necessary files to build and run XRDA. 1) Copy (or download) all files from the diskette (the ftp site) to an appropriate directory on your hard disk. IGNORE -> 2) Run "x**.exe". This will decompress the main program under the final name "xrda.exe". 3) In the Windows environment, in the Program Manager (Windows Explorer), create a new item ("New " in the "File" menu) with the appropriate command line i,e, /[path]/xrda.exe and the default data directory. By "clicking on "Ok", an XRDA icon should appear in the selected window. 4) You may also start XRDA from the Windows "File Manager" (or Windows Explorer) by clicking on "x**.exe". 5) The following is an example of how to use basic XRDA commands to analyze an energy dispersive X- Ray spectrum. EXAMPLE Beforehand, a gold calibration diffraction spectrum was processed to retrieve Ed (Ed=64.82±0.029 keV.Ĺ), and we shall now analyze a spectrum consisting of stainless steel (hcp) and gold (fcc). Gold is used here as the pressure gauge. This data was collected on the CHESS B1 line, which uses the hard bending magnet. The data file used is SSAU.DAT and the associated analysis file is SSAU.XRD. • Once XRDA is started, you can load the data file by selecting File/Open (or Ctrl-O). Select the type of file in the Open dialog box: Data Files (*.DAT). Then select the directory and file to be loaded. • When ready, XRDA displays the spectrum in the "X-Ray Diffraction Plot" window. You are ready to fit peak profiles. • To analyze this spectrum, I choose to use Lorentzian line profiles with a linear background. To fit a single peak or a series of peaks (maximum 9 at a time), select the Analyze/General Fit menu command. From the dialog box, select the type of peak profile and background you want to use. When selected, press the OK button. In the Plot window, enter the left range limit with the LEFT mouse button (LMB), then select the approximate positions of the peaks with the RIGHT mouse button (RMB). When finished, enter the right range limit with the LEFT mouse button. The program now computes the desired peak profiles. You may decide to cancel the fit by pressing ESC. Otherwise, when the fit is complete, the new peaks will be displayed in the Peak Fitting window (under Phase I), and their profiles will be drawn in the Plot window. Do this for all the peaks you want to fit. To analyze a peak (or group of peaks) with a Lorentzian line profile with a linear background, you may also click on the left hand side ButtonBar labelled "L". • Peaks from a certain structure can be groupped in a specific phase by dragging the peaks to where you want. Double-clicking with the LMB will display all the peak information as well as its Miller indices (if entered). (Phase I is for Mo and Phase II for stainless steel in our example) • Before fitting a structure, you must enter Ed, using the Ed button on the ButtonBar or selecting the Lattice/Set Ed menu. • Press the button corresponding to a known phase to enter and display information on that phase, such as the lattice structure, the atomic positions .If With a sufficient number of peaks with assigned hkl's, you may initiate a lattice parameter fitting by pressing the Fit Structure button. In the Peak Fitting window, the refined lattice parameters are displayed, and the calculated energies and intensites for each peak is displayed in the Calculated Energies and Intensities window. • Repeat this for all the existing phases. You then have solved the spectrum. An intensity histogram for each phase can be displayed in the Plot window. Select the Plot Options/draw , hkl/phase # to draw a calculated intensity histogran of the desired phase. At least one atom (at (0,0,0)) should be entered before calculating diffraction intensities. • Using the parameters for the Murnaghan or Birch-Murnaghan EOS for Au as entered in the Phase Info dialog for Phase I, you can determine the pressure at which the spectrum was taken. Experiment with other XRDA features: like using the ButtonBar for easy access to many functions, options for intensity calculations or plot display, etc. To support future releases, a financial contribution would be welcome. Think of how much a commercial package like this one could cost! ------> The author disclaims all responsibilities regarding the use of XRDA. <------- YOU CAN HELP... If you think that XRDA is useful for your applications, please send your monetary contribution ( 1/4 of what you think the cost of similar commercial package is ; we suggest $110 US or $150 CAN) to help developping and distributing future versions. Send a cheque to: Prof. Serge Desgreniers Dept. of Physics, U of Ottawa 150 Louis Pateur Ottawa, Ontario, Canada K1N 6N5 COMMENTS ? Thanks for using XRDA. Please send your comments to Dr. Serge Desgreniers Département de physique Université d'Ottawa 150 Louis Pasteur Otttawa, Ontario Canada K1N 6N5 (613) 562-5800 x6757 (613) 562-5190 (FAX) e-mail (preferred): serge@physics.uottawa.ca