Anomalous scattering method in crystallography on the basis of parametric X-radiation

Spectra of parametric X-radiation (PXR) in the range of anomalous dispersion of atoms of a crystallographic unit cell are theoretically analyzed. Characteristics of PXR are calculated for both ultrarelativistic (E ≥ 50 MeV) and non-relativistic (E ≃ 100 keV) electrons interacting with complex organic crystals. The analysis of the PXR angular distribution is shown to permit the realization of the anomalous scattering method for the direct measurement of structure amplitude phases.