Plot85 Tutorial

Last updated March 20, 2009

This document is a tutorial for Plot85. For more details, please refer to the Plot85 Instructions, which is a description of all the menus organized by function.

Plot85 is a Windows-based Fortran program for plotting X-ray diffraction data. It was originally written for data created by the SAM85 control program (hence its name), but has been extensively enhanced:

  1. It will work with both energy dispersive and angle dispersive data
  2. Input files are ASCII text files
  3. Input files may be in the original SAM85 format, the APS MCA format, the APS MED (Multi-Element Detector) format,GSAS format, or X-Y (2q-I) data. The first three formats are for energy-dispersive data, and must have associated calibration information. The other two (GSAS or X-Y) are for angle-dispersive data and must have the wavelength used entered in another step.
  4. Input files in the APS MCA format can be for a single detector or up to 10 detectors

Comparisons can be made with various reference patterns in several formats:

  1. A text file (e.g. STANDARD.HKL) which lists the h,k,l,d, and I for each of up to 20 diffraction lines for each of up to 25 materials. Typically used for calibration standards and common cell materials.
  2. A text file for each material which includes the same information, but in the .JCPDS format (up to 60 lines for one material).
  3. A text file containing crystal structure data in XPOW format
  4. X-ray fluorescence for all the K lines. This data is built into the program
  5. Another diffraction pattern which has the same calibration information as the pattern under investigation

The steps in normal use of the program are:

  1. Open a data file in any of the above formats. If the calibration information for energy dispersive data is in a file called DEFAULT.EDF (and the program can find it), that calibration information will be used. If there is no external calibration file called DEFAULT.EDF, the calibration data which may be built into the data file will be used.
  2. Plot it. The plot will be in terms of channel number for energy-dispersive data. If you want to determine the energy or the d-space corresponding to any particular peak, you can select it or fit it.
  3. Selection a reference and plot its lines.
  4. Select the region to expand by entering 3 keystrokes: 2 dots (periods) define the region. The third keystroke, if it is another dot, will simply expand the scale to the region selected. If it is a "/", then GPLS will be invoked using that region as the ROI (Region of Interest).
  5. Select the peaks of interest by either pointing to them (one at a time) and pressing the appropriate key, or fitting them with GPLS. The resultant list of peaks will be saved into a peaks file which includes the channel number, d-space, energy, and hkl, if known. If the peak was determined using GPLS, the goodness of fit, peak width and a few other parameters will also be included.

Other enhancements in the program include:

  1. Ability to use up to 10 detectors arranged at different positions (version 4.1 or later) and compare the resultant d-spaces (for measuring strain, for example) (version 5.5 or later). Ten detector data requires version 7.4 or later
  2. Peak search using the routine POW by Wayne Dollase (version 5.0 or later)
  3. Can use PDF2 output from the Powder Diffraction Database (version 5.1 or later)
  4. Can "tweak" the energy calibration to compensate for small changes during a run (Version 5.7 or later)
  5. Do a complete energy and 2q calibration (version 5.8 or later)
  6. Do a complete energy and 2q calibration for up to 10 detectors automatically (version 7.5 or later)