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EXPGUI, part 5

A.5 Profile panel

The Profile panel is used to edit the profile values as well as their refinement flags and damping value. Note that there will be a set of profile parameters for each phase present in each histogram. New! The "Change Type" button is used to select a new profile type for one or more histogram/phase combinations.

Note that the order that histograms appear in this panel is determined by the "Sort histograms by" option in the Options Menu.

EXPGUI Screen snapshot
When more than one phase is present in the histogram, the profiles for all phases are shown.
EXPGUI Screen snapshot

EXPGUI disables the refinement flags for profile terms trns or shft when the histogram zero point correction is refined. Neophyte users of GSAS sometimes incorrectly attempt to refine these terms together, which almost always causes problems. (Note that histogram Zero is refined for parallel beam diffraction instruments, typically synchrotron or neutron diffractometers, while trns and shft are appropriate only for Bragg-Brentano geometry [typically lab x-ray] instruments. In the Bragg-Brentano case, shft is related to the displacement of the sample from the scattering plane, which is usually subject to error and thus should be refined and trns is a correction for sample transparency, which is typically refined only with a low density sample.)

If "Multiple Histogram Selection" mode is set to "All", this panel is disabled. For other settings of this mode, profile values and settings can be collectively modified for groups of histograms and the panel appears slightly differently, as is seen below:

EXPGUI Screen snapshot

A.5.1 Edit Profile Type

Pressing the "Change Type" button causes a window like the one below to be displayed.

EXPGUI Screen snapshot

Note that the default profile values are taken from the instrument parameter file (in the example above, a profile was selected where no such default values were defined and the current values (where appropriate) are taken from the current profile function. Through use of the appropriate buttons, selected values can be retained from the current profile when the function is changed or can be reset to default values. This latter capability can be useful even when not changing the profile type, if the profile terms have refined into a false minimum.

A.5.2 Profile panel

EXPGUI Screen snapshot

When the button labeled "Global Edit" is pressed ( "Multiple Histogram Selection" mode must be set to a single histogram type) the dialog above will be displayed. The entry boxes will appear blank and only those terms that are filled in will be changed when the "Set" button is pressed.


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