Commission on Electron Crystallography


Triennial Report 1993-1996

At the Beijing Congress, the members of the Commission spent some time discussing the appropriateness of the continued inclusion of the gas electron diffraction community in its membership. Subsequent discussions have persuaded the Commission that this community's best interests would be served by transfer to the Commission on Small Molecules and steps have now been taken with a view to making this change.

The period under review has seen the rapid expansion of interest in a wide range of applications of quantitative electron diffraction. This has been stimulated by the arrival of various models of commercially available transmission electron microscopes with facilities for energy-filtering electron diffraction patterns. The elastic-only diffraction patterns are capable of being analysed to give accurate data about bonding charge distributions, atom locations and strains. In recognition of these developments, the Commission organized, with IUCr financial support, two workshops on Electron Crystallography - Theory and Practice. One of these was held in the East, at Beijing, in association with the Beijing Congress, the second in the West, at Bristol and Bath, UK, in association with the 13th International Congress on Electron Microscopy in Paris, France. Both workshops were judged as considerable successes, each with an attendance of about 50 people from 20 different countries.

This period has also been one of the flowering of surface electron diffraction techniques and theory. It was therefore decided to organize a round robin of those who had written computer programs for calculating surface electron diffraction data and to run a workshop on the subject. This workshop, held in Arizona, USA, in January 1996, was also sponsored by the IUCr and attracted 75 attendees with 16 invited lecturers from five different countries.

At the Beijing Congress the Commission was responsible for a microsymposium on Direct Phasing from Electron Diffraction Data. Building on the success of that meeting, the Commission has been responsible for the organization of five microsymposia at the Seattle Congress.

23 January 1996 J. W. Steeds, Chairman