Dear Mike,
Normally, changing sollers must not influence the signal/background
ratio. Wider sollers, however, make the primary beam wider and if the
sample diameter is small then a parasitic scattering from the sample
holder edges may appear.
I am really surprised that moving from 0.04 Soller slits to 0.02 you
got 25 times intensity reduction. When I change the primary soller from
0.04 to 0.02 the intensity drops ~2 times, so if you changed both the
primary and the secondary sollers the intensity should decrease ~4
times, but not 25 times.
Leonid Solovyov
> How do you define signal to noise in powder diffraction? I have seen
> this term used several times, but I have not found a definition so
far
> with regard to powder diffraction per se.
> I have just done two runs on a Panalytical one with 0.04 soller slits
> and one with 0.02 (both with a CuKa1 premonochromator) both for
about 9
> hours. The strongest peak for the 0.02 case is 2700 counts, half
width
> 0.08 degrees and a background of 25 counts. The same peak with the
0.04
> slits has 70000 counts, half width 0.11 degrees and a background of
> 700 counts.
>
>
> Mike Glazer
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