Secondary extinction and neutron crystallography

摘要: A detailed study of the effects secondary extinction is made, with particular stress on behaviour virtually non-absorbing crystals introduced by advent neutron diffraction. The penetration a beam into mosaic crystal this kind will always be complete, and relative importance absorption reverse that familiar in X-ray techniques. It found increasing thickness integrated reflexion falls away from proportionality to F2 and, for normal thicknesses, has values order spread expressed radians. There useful range where proportional F, as perfect crystal. discussion leads an illuminating comparison between primary extinction. Criteria `thin', `thick', `non-absorbing' `absorbing' are given. these results crystallography discussed; if technique similar goniometry developed, then even smaller than those conventional required. For work best greatest spread.