Link to NIST Center for Neutron Research home page Link to National Institute of Standards & Technology home page
Link to Tcl/Tk information

GSAS Nickel example using EXPGUI (part 6)

6. Plot data using POWPLOT or LIVEPLOT

At this point in the GSAS tutorial in the manual, program POWPLOT is used to plot the diffraction data. This is done by pressing POWPLOT button in the button bar, or by pressing the POWPLOT menu item in either the Powder menu or the Graphs menu. The input supplied to POWPLOT and the results are the same as what is shown in the manu, so this will not be shown.

EXPGUI does offer another way to display diffraction data, LIVEPLOT. Similar to the way POWPREF was run in the previous step, LIVEPLOT can be started by pressing LIVEPLOT button in the button bar, or by pressing the LIVEPLOT menu item in the Graphs menu.

Since no cycles of refinement have been run, after LIVEPLOT generates a blank screen, it must be triggered to read the POWPREF output by pressing the "Update Plot" item in the File menu. A plot similar to the one to the left.

Note that the region plotted can be changed by clicking with the left mouse button, two outline the region to be shown, as seen to the left. When the left mouse button is pressed a second time, the graph is "zoomed in," as is shown below. To "zoom out" to the previous region, press the right mouse button.

Reflection positions can be marked, using the File/Tickmarks menu.

Reflection indices can be displayed by pressing the "h" (or "H") key in the position of the reflection to be labeled. The size and time before the reflection labels are removed is determined by values in the Options/HKL labeling menu.

There are many other options available in LIVEPLOT in the Options menu. The Appearance and location of the tickmarks can be set. The symbol and symbol size used for observed data can be selected. The X and Y units can be changed to Q or d-space values. Background can be subtracted. The legend can be removed from the plot.

Previous step: Run POWPREF
Next step: Setup for Least-Squares Refinement

Brian Toby (Brian.Toby@NIST.GOV)
$Revision: 162 $ $Date: 2009-12-04 23:01:26 +0000 (Fri, 04 Dec 2009) $