Kurt (& others),
The real problem with small samples in Bragg- Brentano geometry is assuring
that the sample covers uniformly the entire "foot print" of the incident
x-ray beam at all scattering angles used in the scan, i.e. there are no
"bare spots". If this is not achieved then the observed diffraction
intensities will bear little relation to what should be observed
(particularly at low angles). The sample thickness for typical samples
(metal oxides, say) is infinite at 20 or so microns so the problem isn't
the thickness but is ensuring the coverage.
Bob Von Dreele
At 05:44 PM 11/7/99 -0700, you wrote:
>Rietvelders,
>
>For a lot of small powder samples (say 10 milligrams) in Bragg-Brentano
>geometry, the sample has to be spread very thin over the diffracting
>surface of a slide in the diffractometer. I notice that a lot of the
>textbook formulas are for "infinitely thick" samples. Is there a special
>way to deal with the thin samples? It seems like the absorption part of
>the formula for peak intensities (for example, for phase fractions in
>multiphase mixtures) will be changed.
>
> - Kurt Leinenweber
>
>*************************************
>Kurt Leinenweber
>Dept. of Chemistry
>Arizona State University
>Tempe, AZ 85287-1604
>
>Phone (480)-965-8853
>Fax (480)-965-0474
>
>************************************
