After having purchased the set of 0.02 soller slits in Dec. 03 I have
done some comparison tests on the (111) silicon peak under identical
conditions except for the change of the primary and secondary sollers:
background Bpeak height PH
0.0295 8580
0.04
Alan Hewat wrote:
Even if you have a low profile R-factor (due to a high background and a
low resolution pattern) the calculated standard deviations in parameters
can still be large, which gives me confidence in Rietveld refinement :-)
I hoped the values of esds come out similar to the ones put
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 sli
Jon Wright said:
> a high background is a fine addition to any instrument; it
> gives a much lower profile R-factor. This tells us something about the
> value of the profile R factor, I think ;-)
A low resolution pattern is also easier to fit :-) The profile R-factor is
certainly not an absolute
Alan Hewat wrote:
Many theoretical arguments about signal/noise forget that the
experimentalist has a finite time to collect his data :-)
The finite time to analyse and publish can also be rate limiting! In
this respect a high background is a fine addition to any instrument; it
gives a much l
As Mike implies, for a given counting time, you have much better
statistics using the high intensity configuration. This can be true even
when the signal to noise ratio is actually lower with the high intensity
configuration. So signal/noise is not everything.
That said, there is no point in reduc
IMHO,
plenty of "counter" problems have their roots in the past. When
the first GM counters were used in powder diffractometry the apparatus
(both
electronics & math) was taken directly from the field of \alpha-particles
physics.
Because \alpha-particles are rather rare (events), people used
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 premon
Leonid Solovyov wrote the following on 18/02/2008 16:27:
Yes it is mainly down to the Soller slits,
there was a very large thread on
soller slits somewhere in the Rietveld archives
about this discussion. I think the down side of
changing the soller slits is a move away from the
optimum FWHM that
> Yes it is mainly down to the Soller slits,
> there was a very large thread on
> soller slits somewhere in the Rietveld archives
> about this discussion. I think the down side of
> changing the soller slits is a move away from the
> optimum FWHM that can be obtained?
Changing sollers from 0.04 r
Yes it is mainly down to the Soller slits, there was a very large thread on
soller slits somewhere in the Rietveld archives about this discussion. I think
the down side of changing the soller slits is a move away from the
optimum FWHM
that can be obtained?
Quoting Leonid Solovyov <[EMAIL PROTEC
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