Re: [sdpd] how to purchase a high resolution diffractometer

[cockcroft...@gordon.cryst.bbk.ac.uk]

With regard to the geometry, I would suggest that you go for a transmission
setup and not the standard Bragg-Brentano reflection one if you want
a setup dedicated to structure determination/Rietveld refinement.
We have both setups in our lab here, and it is fair to say that >95%
of the data collected for refinement purposes with reflection geometry
seems to end up with preferred orientation effects. I can be sure of this
by simply running the same sample in transmission mode.
Both of our machines have primary beam monochromators - yes, there is a loss
of intensity, but I prefer the extra "resolution" I get the higher angles
due to the pure alpha1 wavelength.
      Jeremy Karl Cockcroft
(School of Crystallography, Birkbeck College).
P.S. Incidentally, some of these points are taught on our powder diffraction
web course. The above point was really brought home to many people in
an informal round-robin exercise carried out by the Industrial Group
of the British Crystallographic Association with the results presented
at the annual meeting last April.

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