Commission on Electron Crystallography


Annual report of International Union of Crystallography Commission on Electron Diffraction


Written April 2004 by John Spence

As the boom in nanoscience continues, the past year has been a remarkable year for electron diffraction. Especially notable, following the award of the Nobel prize to A. Zewail, has been the growth of time-resolved electron diffraction in the gas phase, with pulse durations now down to 400fs. While coulomb interactions limit speed compared to pulsed X-ray work, count-rates are much higher. Fast electron microscope imaging, still at the nanosecond timescale, is now also growing with a large new program at Livermore Labs, Ca., USA. An equally remarkable highlight from the past year is the publication of the first atomic-resolution image of a carbon nanotube (Science, 300,1419). This aberration-free "lensless image" was obtained almost entirely from the electron diffraction pattern of a single tube, using new iterative phasing methods which can now solve the phase problem for non-periodic objects. Throughout the world, scientists are placing orders for the new generation of aberration-corrected electron microscopes, which, together with the new electron monochromators for energy-loss spectroscopy, promise to revolutionize the field. (In the USA, the Dept of Energy "TEAM" project plans to install these in several national labs over the next few years, for example). In biology, the appearance of TEMs dedicated to liquid-helium cooled cryo-microscopy for single-particle, three-dimensional imaging of proteins which cannot be crystallized is producing major advances, and the automation of electron tomography proceeds apace in both materials science and biology. The publication of the first subnanometer-resolution, three-dimensional views inside a mesoporous silicate catalyst must also rank as one of the year's highlights. The year has seen many conferences devoted to electron diffraction and imaging, including MC2003 in Dresden (Sept 7, 2003), the Frontiers of Electron Microscopy conference in Berkeley Ca (Oct 5, 2003), a workshop in Cairns, Australia (June 30, 2003) on the non-crystallographic phase problem , a conference honoring John Cowley, FRS in Arizona (Jan 3, 2003), the Moscow electron crystallography school, a diffraction school in Delft (Jan 22, 2003), the Microscopy Society of America meeting (Aug 3, 2003), the UK EMAG meeting in Oxford (3 Sept 03), a school on advanced HREM in China at the end of 2002 (see below, not reviewed last year) and several conferences in Japan, amongst many others.

Advanced High-Resolution Electron Microscopy (Dec. 23, China 2002)

There were totally one hundred Chinese participants attending the Workshop/ School. Among them three were from other countries, five from Taiwan and one from Hong Kong. Ten experts were invited to given main lectures. They are Dr. Jiang-hua Chen (Delft Univ.), Dr. Jin Zou (Sydney Univ.), Dr. Di Wang (Fritz-Haber Institute, Berlin), Prof. Fu-rong Chen (Tsinghua Univ. Taiwan), Prof. Rong Wang (Peking Univ. of Science & Technology), Prof. Xiao-jing Wu (Fudan Univ.), Prof. Man-ling Sui (Institite of Metals, Chinese Academy of Sciences (CAS)), Prof. Hai-fu Fan, Prof. Fang-hua Li and Mr. Huai-bin Wang (Institute of Physics, CAS)

The workshop/School aims at offering a forum to communicate the new theory and new methods in investigating the crystal structures and microstructures with a resolution higher than the resolution of electron microscope. The topics of this Workshop/School mainly concentrate on solving the inverse problem in high-resolution electron microscopy (HREM) by image processing. Two image processing techniques which were studied most extensively in mainland China and Europe, respectively, and the technique recently developed in Taiwan were introduced including the theories, methods and applications. This indicates a new prospect in the application of HREM. In addition, the advantage and problems of spherical aberration corrected HREM was discussed.

This Workshop/School offered a good opportunity to all participants to learn the fundamental theory and/or recent advances in the field of HREM, and also to report their achievements.