G. Thorkildsen et Hb. Larsen, Nonsymmetrical X-ray diffraction in a perfect rectangular txl crystal. Extinction and absorption, ACT CRYST A, 55, 1999, pp. 1-13
A theoretical investigation of diffraction in a rectangular t x I crystal f
or nonsymmetrical coplanar scattering has been undertaken. The asymmetry in
the scattering geometry, measured by an angle gamma, causes different weig
hts for the mixed Laue-Bragg contributions to the integrated power. Primary
extinction and ordinary absorption are only moderately affected when the v
alue of the geometrical parameter zeta = (t/l) tan theta(oh) < 1, theta(oh)
being the Bragg angle. For increasing values of zeta and gamma the surface
integration set-up for the Laue and Bragg regions is extensively changed,
leading to pronounced effects. Analytical results for the normal absorption
factor are presented.