A Fourier optics approach to the dynamical theory of X-ray diffraction – continuously deformed crystals

X-ray diffraction in continuously deformed crystals is reconsidered on the basis of the analogy between X-rays in crystals and two-level systems in quantum mechanics. The different forms of Takagi's equations are shown to be different ways to represent the same propagation equation. An exact solution of Takagi's equations in the case of a constant strain gradient is given and approximation methods are also considered.

SPEDEN: reconstructing single particles from their diffraction patterns

SPEDEN is a computer program that reconstructs the electron density of single particles from their X-ray diffraction patterns using an adaptation of the holographic method in crystallography. It is designed to deal successfully with sparse, irregular, incomplete and noisy data.

Solving the Sayre equations for centrosymmetric structures with a genetic algorithm

A new method employing Sayre's equations and a genetic algorithm to solve the phase problem is developed for centrosymmetric structures. Compared to simulated annealing, a genetic algorithm is more efficient.

Polyhedral truncations as eutactic transformations

Vector radiations, as particular examples of eutactic transformations, are defined and studied.

Determination of standard uncertainties in fits to pair distribution functions

A methodology for estimation of statistical uncertainties for parameters fit to pair distribution functions is developed.

U₄O₉: atoms in general sites giving the hkl extinctions of special sites

In U₄O₉, the hkl reflections obey the extinction rules for atoms occupying special 12-fold [12(b) of space group I3d] sites. An explanation is given for this effect, which can be generalized to any space group.

Refinement of the structure of β-U₄O₉

The structure of β-U₄O₉ has been refined from single-crystal neutron data in the space group I3d taking into account the findings described in the previous paper.

Application of a modified Oszlányi and Süto ab initio charge-flipping algorithm to experimental data

The structures of two crystals have been solved using a new iterative phasing method developed from the `charge-flipping' method.

Phasing diffuse scattering. Application of the SIR2002 algorithm to the non-crystallographic phase problem

A new algorithm for determining the phases of diffuse elastic X-ray scattering from a non-periodic object is described.

X-ray standing waves in a heterostructure: application to a Zn_1−xCo_xO epilayer on ZnO(00.)–O substrate

X-ray standing waves (XSW) were analysed within the dynamical theory for a thin epilayer and the substrate under the epilayer with application to a Zn_1−xCo_xO epilayer on ZnO(00.)–O substrate.

A graphical representation of image quality for three-dimensional structure analysis of two-dimensional crystals

Data distribution plot for three-dimensional structure analysis of two-dimensional crystals.

High energy electron diffraction and microscopy

Crystal growth for beginners