Absolute measurement of structure factors using a new dynamical interference effect

Abstract

A new method of determining X-ray scattering factors by dynamical interference is described. The theoretical background to the interference effect is discussed in detail and an expression for relating the fringe period to the structure factor is developed. The method relies on anomalous transmission and is therefore most suitable for measurements on nearly perfect crystals of high atomic weight. It also has the attractive property of being insensitive to slowly varying lattice strains. Applying the method to the 220 reflexion of silicon a value of 8.487 ± 0.017 for the atomic scattering factor has been obtained using Mo Kα 1 radiation. This value is in excellent agreement with the author's previous results using the Pendellösung method.