Mario Nardelli (1922–2004)

The structure of short-lived excited states of molecular complexes by time-resolved X-ray diffraction

Recent progress in atomic resolution time-resolved synchrotron X-ray diffraction studies of molecular excited states is reviewed. Experimental and computational aspects of the field are discussed. Experimental results are compared with theoretical calculations on the excited state of the isolated species.

Clifford algebra approach to the coincidence problem for planar lattices

The problem of coincidences between two planar lattices is analyzed using Clifford algebra.

Generalized quasiperiodic patterns and super­structures in quasicrystals

Patterns with octagonal and icosahedral symmetries obtained from periodic two-dimensional (2D) 8-grids and three-dimensional (3D) 12-grids by the dual method are shown to be superstructures of the Beenker pattern and the 3D Penrose pattern with the same edge length.

Reconstruction of complex single-particle images using charge-flipping algorithm

An iterative method combining the charge-flipping algorithm and the dynamic Gerchberg–Saxton–Fienup algorithm is developed to reconstruct complex exit-wave functions of a non-periodic object.

On the algebra of binary codes representing close-packed stacking sequences

A systematic use of binary codes derived from the Hägg symbol are used to study close-packed polytypes. Seitz operators are introduced acting over the space of binary codes. Polytype counting problems are reduced to an eigenvector problem in the binary code space. Space groups of monoatomic close-packed polytypes can be seen as a result of the symmetry of the binary codes.

The Ewald dynamical diffraction theory – ninety years later

Diffraction on a crystalline slab is treated as a multiple scattering problem based on the Ewald equations. The two-beam solution for both coplanar and non-coplanar cases valid near and far from Bragg peaks is found and a detailed comparison with results of Laue's theory is performed.

A study of charge density in copper

A study of charge density in copper from a combination of quantitative convergent-beam electron diffraction and γ-ray diffractometry structure factors.

Solving non-centrosymmetric two-dimensional crystal structures by dynamic electron diffraction

Using dynamic scattering effects to solve the phase problem.

Diffraction and imaging from a beam of laser-aligned proteins: resolution limits

The effect of limited alignment of hydrated proteins is considered in a laser-aligned molecular beam on diffraction patterns taken from the beam. A relationship between laser power, temperature and resolution is obtained, and simulations used to demonstrate iterative phasing of the continuous diffraction patterns.

Intensity of N-beam X-ray diffraction: kinematical theory for a small crystal

A simple calculation method of X-ray diffraction intensity in the n-beam case is constructed on the basis of kinematical theory for a small and ideally imperfect crystal. This method is interpreted as an integrated form of the intensity transfer equations proposed by Moon & Shull (1964).

Qu­antitative structure retrieval at atomic resolution

A method is presented to determine the projected potential of a crystal from a single exit-surface wavefunction obtained at atomic resolution under dynamical scattering conditions.

Mathematical techniques in crystallog­raphy and materials science

Crystal structure determination

Light is a messenger – the life and science of William Lawrence Bragg

X-ray Compton scattering

Report of the Executive Committee for 2003

Ewald Prize awarded to Professor Philip Coppens