On Fri, 12 Feb 1999, Armel Le Bail wrote:
> I would prefer to get one or two of these patterns, if possible, thanks.
>
I will see if I can dig one or two up.
> >Sure! And you can allways fit a peak with consists out of two components,
> >but at times you can be really struggeling to find out whether you see
> >peak splitting due to alp1/alp2 or due to a slight reduction in symmetry
> >or stcking faults. If you can rule out the machine straight away, than
> >life becomes a bit easier.
>
> You cannot always fit any peak which consists out of two
> components when the position, shape and intensities of both
> components are tied. You can fit if and only if your model is
> consistent with those constrained data.
I am NOT talking about a model at all, this is not Rietveld! The only
assumption I make is that alp1 and alp2 behave in the same way, and thus
have the the FWHM, a given intensity ratio, and a related position. If you
are looking at one reflection you can easily fit that to the proper peak
shape. If you have two reflections than it is more complex, and that was
exactly what I was trying to say above.
> Can you give your minimal FWHM, just to see how much your life
> is easy ? With FWHM as low as 0.045 2-theta degrees, you
> already observe well the alpha-1 - alpha-2 peaks separately near
> of 40 2-theta degrees.
In a Pseudo-Voigt fit I get a minimum FHWM of about 0.06 2-theta up to
about 60deg 2-theta, that is on 'real' samples. With these values you will
see a shoulder on intense peaks from 30deg 2-theta upwards.
Best
Jaap Vente
Cinvestav-IPN Unidad Merida
Departamento de Fisica Aplicada
Carretera Ant. a Progreso km 6
Apartado Postal #73 Cordemex
Merida, Yucatan, 97310
Mexico
Fax: (..) 52 - 99 - 812917
Tel: (..) 52 - 99 - 812960 ext 246/233
e-mail: [EMAIL PROTECTED]
