On the polarization factor for crystal-monochromated X-radiation. II. A method for determining the polarization ratio for crystal monochromators

Abstract

An experimental method for determining the polarization ratio K for crystal monochromators is described. Apart from a diffractometer, no additional equipment is required to perform the experiment other than a single crystal. The choice of a suitable crystal is discussed in terms of the theory of the method and from a practical point of view. It is shown that, in the absence of extinction and under certain easily attainable conditions, the crystal can be irregular in shape, of unknown dimensions and highly absorbing. The method has been tested on modelled data and applied in the determination of K for three wavelengths of radiation. The method may be adapted to powder diffractometry. A seemingly simpler method of determining K by least-squares refinement techniques gave unsatisfactory results.