Diploma Thesis - Erich Schmid Institute

X-ray Diffraction – Measurements and Alignment
so that the centre of the top face is in the middle of the laser spot. Afterwards the
shade holder together with the laser is removed and the detector is turned back to
0° position. Afterwards a dial gauge is mounted in fro nt of the diffractometer plate to
adjust the height to 5,75 mm.
The top surface of the metallic block intersects with the ω−axis. If no radiation is
detected by opened shutter the height of the monochromator is too low and all
radiation will be adsorbed by the metallic block (figure 9.6a). Otherwise if it is too high
the detector will measure the full intensity (figure 9.6b). To find the correct height the
monochromator is moved in such a way that half of the maximum intensity is
measured, so it is guaranteed that the X-ray beam intersects with the ω−axis
(figure 9.6c).
a.) Monochromator is too low b.) Monochromator is too high c.) X-ray beam intersects with
rotation axe
The fine adjustment is done by rotating the metal block around ω−axis. A scan shows
that the intensity has a maximum at a certain ω−angle (figure 9.7). It is supposed that
at the maximum intensity the top surface of the metallic block is parallel to the
incident beam, so the deviation from the zero ω−angle can be electronically
corrected. The last step is to measure gold standard like it is done in the point focus
alignment.
Figure 9.6: Height adjustment of the monochromator
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