The breadth and shape of instrumental line profiles in high-resolution powder diffraction

J I Langford, R J Cernik, D Louer

    Research output: Contribution to journalArticlepeer-review

    Abstract

    The instrumental resoln. function for the Daresbury 9.1 high-resoln. powder diffractometer was measured as a function of wavelength, slit width and specimen geometry. The effects of size and strain from the sample of annealed BaF2 used as a ref. material were negligible, and it is a suitable std. for studying instrumental broadening. The results of considering the angular dependence of the Lorentzian and Gaussian components of the integral breadths of instrumental line profiles are in excellent agreement with those predicted by the receiving-slit width and the known wavelength spread in the incident beam. The measured instrumental resoln. function is dependent on the slit dimensions at low and intermediate angles, and is dominated by the effects of angular dispersion at higher angles. The line shapes are predominantly Gaussian at low angles and for a flat sample tend to a pure Lorentzian shape at 180°. The line profiles for a capillary sample are similar at low and intermediate angles and tend to an intermediate Gaussian/Lorentzian form at high angles. [on SciFinder(R)]
    Original languageEnglish
    Pages (from-to)912-18
    Number of pages893
    JournalJ. Appl. Crystallogr.
    Volume24
    Issue number5
    DOIs
    Publication statusPublished - 1991

    Keywords

    • Diffractometry (x-ray, powder, breadth and shape of instrumental line profiles in high-resoln.)
    • powder diffraction instrumental line profile shape

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