Experimental determination of the extinction factor by the use of polarized X-rays

The problem of estimating the extinction factor by use of polarized X-rays has been re-examined in the light of the theory of X-ray diffraction in real crystals developed recently by Zachariasen. Expressions are given for deriving the extinction-free structure factors in terms of the observed integrated intensities for perpendicular and parallel polarizations. A simple attachment to a diffractometer for analysing the polarization of the diffracted beam is described. Measurements on quartz are presented; the extinction-free structure factors so obtained are in excellent agreement with Zachariasen's calculated values based on new f curves.