Using either fundamental parameters (Koalariet/XFIT, BGMN and Topas)
and/or FCJ assymmetry correction code (Fullprof, GSAS, Rietica, etc) -
can the assymetry on the coarser Sollers slits be modelled effectively
on the new Philips systems?
Coarser slits have the advantage of much higher intensity, better
particle statistics which if assymetry can be effective modeled -
would be an advantage in some areas of Rietveld analysis.
It would also be interesting to see diffraction plots using
the different Sollers slits settings if/when these can be
made available.
Lachlan.
>
> One item is especially important for Rietveld work, namely the peak
> asymmetry due to axial divergence. Generally, Philips delivers 0.04 rad
> Soller slits with its optics, but these Sollers produce quite important
> asymmetry even at the higher angles. It proved extremely difficult to fit
> these peaks, even using a Pearson VII, without resorting to fundamental
> parameters approaches. We have recently performed quite a large amounts of
> tests and calculations to find out how we could reduce the asymmetry and
> what optics is best suited for Rietveld spectral acquisition. I will
> shortly send a few pages as a report of this to this list. In any case, it
> is imperative that 0.02 rad Soller slits are purchased from Philips to get
> decent spectra for Rietveld use.
>
> As far as software goes, the X'Pert Plus package is the Rietveld refinement
> software Philips delivers. Although it is not THE most powerful package in
> existance, it is definately the most easy to use and very versatile. It is
> based on the LHPM engine, but it has an easy-to-use GUI, without reducing
> the control of the user over the refinement process. The fact that it even
> allows refinement of neutron spectra and it can read .RAW Bruker data proves
> that the people from Philips have tried to produce a product with a lot of
> features and not just oriented towards their goniometer.
>
> I'll be happy to answer specific questions on the X'Pert Pro system.
>
> Sven Van den Berghe
>
> ****************************************************************
> Sven Van den Berghe
> Assistant Scientific Researcher
> Reactor Materials Research Department (RMO)
> Laboratory for High and Medium Activity (LHMA)
> Boeretang 200
> B-2400 Mol
> Belgium
> Tel. : +32 14 33 30 64
> Fax : +32 14 32 12 16
> E-mail : <mailto:[EMAIL PROTECTED]> [EMAIL PROTECTED]
> ****************************************************************
>
>
--
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: [EMAIL PROTECTED] Ext: 3703 Room C14
http://www.ccp14.ac.uk
