Polarization anisotropy of X-ray atomic factors and `forbidden' resonant reflections

In the resonant region near an absorption edge, a polarization anisotropy of the local X-ray susceptibility results in additional reflections otherwise forbidden by screw-axis and/or glide-plane extinction rules.

The algebraic approach to the phase problem

The algebraic approach to the phase problem for the case of X-ray scattering from an ideal crystal is extended to the case of neutron scattering, overcoming the difficulty related to the non-positivity of the scattering density.

Graph-theoretical characterization of periodicity in crystallographic nets and other infinite graphs

A method is proposed for determining the isomorphism class of nets from their quotient graph, independently of any embedding.

Extended X-ray interbranch resonance concept for crystals with a one-dimensional deformation

The X-ray interbranch resonance concept is extended to crystals with a one-dimensional deformation. The new interbranch effect is predicted for a strongly distorted crystal with thickness of the order of the interbranch extinction length.

Electron crystallography of zeolites – the MWW family as a test of direct 3D structure determination

The 3D crystal structure of zeolites in the MWW framework family is determined from electron diffraction intensities by direct phasing using maximum entropy and likelihood. Although the `missing cone' left from incomplete goniometric data sampling leads to a somewhat distorted model, the true zeolite framework geometry may be recovered by imposing conservative bonding restraints.

Polarization factors in the general case of three-wave diffraction

Analytical expressions are derived for the polarization factors of three-wave reflections which are functions of the geometrical relations between the relevant crystallographic planes and the spectral and polarization characteristics of the incident radiation.

Crystallography of modular materials