Re: Sample height vs Zero point (continued)

Armel Le Bail ( armel@fluo.univ-lemans.fr )
Thu, 02 Apr 1998 13:58:53 +0200

>What are we going to believe, what are the real SD's and how are we going
>to measure it? Friends what are your thoughts?

Just want to add confusion :-).

Last pattern I rietveldized with FULLPROF had considerable
asymmetric profile shape. With pseudo-Voigt and asymmetry
parameters, the zero point was 0.07, Rp=13.6 %. With split
pseudo-Voigt, the zero point was 0.01, Rp=10.2 %.....

I am tempted to write that a bad fit of considerable peak asymmetry
may lead to quite wrong zero point.

Now if you have transparency effect + large asymmetry (which
is likely to occur with some diffractometer geometry), I don't
know what could happen if the software has not adequate
asymmetry correction.

Armel Le Bail - Universite du Maine, Laboratoire des Fluorures,
CNRS ESA 6010, Av. O. Messiaen, 72085 Le Mans cedex 9, France
http://fluo.univ-lemans.fr:8001/
http://www.cybercable.tm.fr/~cristal/welcome.html