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

["L. Cranswick" <L.M.D.Cranswick...@dl.ac.uk>]

For indexing purposes - how would the "transmission" mode system compare
to a Bragg-Brentano reflection system?

Lachlan.

> 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.
> 
> 
> 
> 
> 


-- 
Lachlan M. D. Cranswick

Collaborative Computational Project No 14 (CCP14)
    for Single Crystal and Powder Diffraction
Daresbury Laboratory, Warrington, WA4 4AD U.K
Tel: +44-1925-603703  Fax: +44-1925-603124
E-mail: l.cranswick...@dl.ac.uk  Ext: 3703  Room C14
                           http://www.ccp14.ac.uk


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