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When
high-resolution measurements are required it is strongly recommended
to allow the complete system to reach a stable temperature before
starting to collect data. This should include allowing the sample
temperature to be the same as the mounting plate.
Note:
Time can be saved by storing future samples within the instrument
enclosure ready for use.
Aligning Using X-rays
If it is possible, use the sample that is large and flat. The alignment procedure is as follows:
Mount a Motorized Z Translation Stage.
Center the sample in the center of the goniometer.
Set all axes: 2Q, W, F and Y to "0" and make sure that the direct x-ray beam is not obstructed by the sample or Eulerian cradle.
Place Cu attenuation foil onto the diffracted beam optics in order to protect detector.
Perform 2q scan through the 2q = 0o position using small receiving slit to find the peak position of the direct beam. Make note of the 2q peak position.
Use Data Collector to recalibrate the 2q = 0o position to coinside with the peak position of the direct beam. Make a note of the peak intensity Ip.
Set 2q = 0o and move the sample with small increments of Z until the direct beam intensity is equal to Ip/2.
Make a small w scan and note the maximum intensity Im.
The next action depends on whether Im > Ip/2, or Im < Ip/2.
If Im > Ip/2, move the sample forward with small increments of Z until the maximum intensity measured in w scan, Im, equals Ip/2.
If Im < Ip/2, move the sample backwards with small increments of Z until the maximum intensity measured in w scan, Im, equals Ip/2.
Move the goniometer to the peak position of the w-scan where Im equals Ip/2 and make a note of Full Width at Half Maximum (FWHM) of the peak.
Measure the FWHM of the peaks in a series of w-scans with the y angle changing in steps of 0.5o around the starting position.
Set the y angle at the value that produces the minimum FWHM. (Alternatively, you can also automatically optimize the y setting in a series of w scans using the optimize program in the data collector software).
Move w to the peak position and recalibrate the w = 0o position using the data collector. The sample is now aligned at optimal 2q, w, y and z settings.