Dynamical Diffraction

Abstract

The theoretical basis for coherent x-ray diffraction is the dynamical diffraction theory. It is introduced here on the basis of microscopic electromagnetism, using the vector potential, charge densities and currents, instead of the electric field and susceptibilities, as is usually done. Based upon this approach, the theory is extended in two ways. The first is an explicit inclusion of time dependence by a combination of Kato’s eikonal theory with the Takagi theory. Order-of-magnitude estimates can be obtained directly from that theory without running a computer simulation. The results will be needed in ch. 4. The other extension of the dynamical theory is the inclusion of nonlinear optical effects. These results will be needed in ch. 5.