diffractions, loosing spatial resolution by the beam intersection with the sample getting too large at low ω, and risking a collision between the sample and the collimator. At higher angles, the problem is the sample interferes with its own low angle diffractions, which is a particular problem for phase identification with the PDF database which has data greatly skewed to low angle measurements.
With the Short Collimators, the maximum range is about 15<φ<60.
With the Long Collimators, the maximum range is about 35<φ<60.
If you need large angular variation, be sure to test the motions to make sure no collisions can occur.
For speed, and exposures longer than 5 minutes, 1 degree/minute is fine.
Phi-axis: You must choose between “Fixed” and “Oscillation” and “Spin.” Assuming the sample is mounted such that its surface flat or convex and is essentially normal to Phi, then “Oscillation” or “Spin” will work. There is the potential for a collision of the sample with the Beam Stop only with thin sections, so you will have to experiment to see what will work.
Again, Spin or Oscillation with ‑180<φ<0 is good.
For speed, and exposures longer than 5 minutes, 3 degree/minute is fine.
Set Omega to an angle where there is no risk of the collimator hitting the sample. 90 degrees is always a good option, or the maximum ω value for the Run Settings
Install Collimator: A short collimator works best with solid samples greater than 1 cm diameter, but a long collimator can be used with care (see below). Mount a collimator on the instrument, choosing a collimator diameter appropriate to the grain or object size on the sample – generally the short 0.1 mm Monocap collimator for optimum spatial resolution and adequate diffraction intensity (the Monocap collimator costs over $10,000 – be very careful with it and always return it too the wooden case when finished or removing it). The Long Collimators provide a greater range of spot sizes but at limited OMEGA oscillation and intensity.
BEAM STOP is not required except for thin sections: Use the long beam stop for thin sections and test for collision conditions.
Do a Test Run if this is the first time you have used these settings.
Press the Measure / Execute button at bottom of the Rint Rapid Screen. The finish time of the measurement will appear in the XXX window.
If the X-ray tube conditions have not been set, the system will raise the kV and mA to operating conditions. Next you will hear a motor inside the main cabinet driving the Image Plate down to the erase position. Several seconds will pass before the Image Plate is clean. More motor noises will occur, as the Image Plate is raised to the Expose position. This will be followed by the RED shutter light on the X-ray tube and the ORANGE X-RAYS ON lamp atop the Rigaku cabinet showing X-ray shutter is open. A screen pops up on the computer indicating that this system is in operation and the time at which the measurement will be finished.
After the Rigaku completes the X-ray run, the sound of the image building on the secondary IMAGE Screen of the RINT Rapid Software takes place. This too, presents a grinding noise as the UV light passes over the image plate, resulting in the fluorescence of the stored energy. It is this released energy