Nonsymmetrical X-ray diffraction in a perfect rectangular t x l crystal. Extinction and absorption.
A theoretical investigation of diffraction in a rectangular t x l crystal for nonsymmetrical coplanar scattering has been undertaken. The asymmetry in the scattering geometry, measured by an angle gamma, causes different weights for the mixed Laue-Bragg contributions to the integrated power. Primary extinction and ordinary absorption are only moderately affected when the value of the geometrical parameter zeta = (t/l)tanstraight theta(oh) < 1, straight 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.
Thorkildsen
G
Department of Mathematics and Natural Science, Stavanger College, Ullandhaug, 4004 Stavanger, Norway. gunnar.thorkildsen@tn.his.no
Larsen
HB