> ... not at all for magnetism, ...
Ahem, magnetism - resolution is very useful, in certain (rare) cases. I
guess that magnetic structures are not Armel's primary interest
but in at least one case resolution was essential. (FeAsO4 from IRIS (TOF
neutron) dataset, J.Phys:Condens.Matter 11 (1999) 1473, apologies for the
gratuitous self reference!). The resolution was needed for indexing a
helimagnetic structure with peaks around d=7A.
Bets wishes,
Jon
PS: I'm not sure how relevant this is but my impression is that the TOF
instruments get better at longer d-spacings. This can be seen on plots of
FWHM vs "effective" 2 theta (or sin(theta)/lambda). As such, I guess there
would be a better example than the MgO, which is only going to about
d=2.1A(?). I have an HRPD dataset with a peak (in backscattering, ie. high
res.) at 3.3A, but the sample broadening is awful. So there is probably an
even better dataset out there somewhere (collected with the choppers at
5Hz, or re-phased).
On Sat, 25 Sep 1999, Armel Le Bail wrote:
> Any new value and place welcome. Remember where this (stupid?)
> comparison takes place, before to explode : SDPD (Structure
> Determination by Powder Diffractometry),
... not at all for magnetism, ...
> tunability of wavelength and so on, only SDPD for which resolution
> counts, first for indexing, then for extracting structure factors used
> for solving, and finally for refining by the Rietveld method : this
> whole process being called "(ab initio) structure determination".
>
> Best,
>
> Armel
>
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