What does the error message „insufficient angular range“ mean?

Short answer

The measured scan exceeds the angular range, in which the peak profile was calculated from the instrument configuration file. Clip your measured data using the keywords „WMIN“ (minimum angle) and „WMAX“ (maximum angle) in the refinement control file (*.sav) to limit the angular range of your scan to the range specified in your instrument configuration.

Example

Suppose the peak profile was calculated from 4 to 150° 2θ, but your scan was measured from 3 to 80° 2θ. This will trigger the error message, because the peak profile was not computed for the range from 3 to 4° 2θ. Add the following line to your refinement control file (*.sav):

WMIN = 4

Then repeat the refinement. Now the measured range from 3 o 4° 2θ will be ignored and the error message should no longer occur.

Long answer

Open your instrument configuration file (*.sav) as follows:

Select „Edit → Edit current FPA configuration“.

The instrument configuration file will be opened in a special editor. Scroll down to the last section, until you find a block that looks like this:

%-----------------------------------------------------------------------------------------------
% Parameters for the simulation of the profile function
%-----------------------------------------------------------------------------------------------

% angular positions for the MonteCarlo simulation (°2theta)
zweiTheta[1]=4
zweiTheta[2]=8
zweiTheta[3]=13
zweiTheta[4]=20
zweiTheta[5]=30
zweiTheta[6]=42
zweiTheta[7]=56
zweiTheta[8]=76
zweiTheta[9]=90
zweiTheta[10]=105
zweiTheta[11]=120
zweiTheta[12]=135
zweiTheta[13]=150

% angular range (°2theta)
WMIN=4
WMAX=150

This shows the 2θ positions at which the profile is simulated (zweiTheta[n]), and the range in which the profile is interpolated (WMIN and WMAX). In this example, the peak profile was modelled in the range from 4 to 150° 2θ. Outside of this range, the profile is unknown. Hence, if a measured scan starting below 4° 2θ, or ending beyond 150° 2θ, is attempted to be refined, the error message „insufficient angular range“ will be shown. There are two different ways to avoid the error message:

• Clip your measured data in order to ignore the measured ranges not covered by the instrument configuration file using the keywords WMIN and WMAX in the refinement control file (example 2).
• Extend your instrument configuration file to cover at least the range you measured (example 3).

For a demonstration of the two solutions, we assume that the instrument was configured in the range from 4 to 150° 2θ, and we are attempting to refine a dataset measured from 3 to 80° 2θ.

Clipping the measured scan

We need to clip the measured data below 4° 2θ, because it is outside of the valid range. In your refinement control file (*.sav), add the following lines:

WMIN=4
WMAX=150

Then repeat the refinement.

Extending the instrument configuration

We need to extend the range in the instrument configuration file from 4 to 3° 2θ. Open your instrument configuration file using the function „Edit → Edit current FPA configuration…“ (or „Edit → Edit FPA Configuration…“ in Profex versions prior to 3.14) and extend the angular range as follows:

%-----------------------------------------------------------------------------------------------
% Parameters for the simulation of the profile function
%-----------------------------------------------------------------------------------------------

% angular positions for the MonteCarlo simulation (°2theta)
zweiTheta[1]=3
zweiTheta[2]=4
zweiTheta[3]=8
...
zweiTheta[13]=135
zweiTheta[14]=150

% angular range (°2theta)
WMIN=3
WMAX=150

Then click „Run calculations“ to start the profile computation. Once it is complete, repeat the refinement. If it runs without error messages, and you want to keep the extended instrument configuration, copy all files .* from your project directory to the devices repository.

Note: In Profex prior to version 3.14, the „Edit FPA Configuration…“ dialog will open in the devices repository. It is important to navigate to the current refinement project first, and open the instrument configuration file found there. Once this version of the instrument configuration file works as expected, copy all .* files from there to the devices repository to make it available to all future refinement projects.