We are currently testing if the fitting of several experimental spectra is
possible using XFit and/or BGMN. After that, we could also test the
asymmetry correction that is coded in Rietica and/or Fullprof. We would
then be able to compare the results of both approaches to the modelling of
the peak profile.
I hope I can get back to you shortly with a full report.
Regards,
Sven
> -----Original Message-----
> From: L. Cranswick [mailto:[EMAIL PROTECTED]]
> Sent: Friday 1 December 2000 12:56
> To: [EMAIL PROTECTED]
> Subject: Re: X-Pert Pro from Philips
>
>
>
> 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
>
