Secondary extinction in an anisotropic crystal

The formalism for secondary extinction developed by Kato is extended to apply to a crystal with anisotropic strain. If an anisotropic correlation for the lattice phase factors is assumed, the formalism can be developed in the same way as for an isotropic crystal. If the geometric average of the correlation lengths of the phase factors is sufficiently smaller than the extinction distance, the ensemble averages of the intensity fields satisfy a set of energy-transfer equations of the same form as in an isotropic crystal. The distribution function of the deviation angle from the exact Bragg condition for the misorientation model of a crystal is given using the notation introduced by Coppens and Hamilton. (orig.)