Dear All, Additional comment concerning the usefulness of variable slits for structure refinement: The angular distribution of the radiation from an X-ray tube is not necessarily uniform, so using variable slits for collection of Rietveld-refined (Bragg-Brentano geometry) data may imply the need for an additional intensity correction for this effect. Moreover, the opening of the variable slits requires an extremely high precision mechanics so there may be a doubt concerning the smoothness of the flux variation with varying two theta, at the given instrument.
Regards W. Paszkowicz
