X-ray microfocussing and micro-imaging techniques truly benefit from all the characteristics of the X-ray beams produced by both insertion devices and bending magnets. Lens-free methods, such as X-ray topography or absorption/phase radiographies (ID19, BM5), can now yield unprecedented quantitative information thanks to the high collimation of monochromatic beams. Optics-based microfocussing techniques, such as microdiffraction and microspectroscopies, exploit the small size and high brilliance of the source. Additionally, following the successful development of focussing optics initiated a few years ago (see previous issues of the Highlights), X-ray imaging with resolutions ranging from a few micrometres to a few hundreds of nanometres is now possible thanks to the wide variety of X-ray lenses currently available at the ESRF. Selected contributions illustrate the use of wave-guides for microdiffraction (ID13), refractive lenses for microfluorescence (ID22) and Fresnel zone-plates for full field X-ray microscopy (ID21). Furthermore, all of these techniques are now used for in situ observation where the evolution of the image contrast of a sample ­ in an appropriate environment ­ is studied as a function of a varying external parameter (temperature, stress, current,...).  

This chapter gives an overview of the most representative results obtained last year with the above-mentioned techniques. The contributions demonstrate the wide range of disciplines to which microfocussing techniques are regularly applied at the ESRF, including engineering and semiconductor materials, crystal growth phenomena, strain determination and trace-element detection in biological materials:

Two contributions illustrate some of the new possibilities offered by high-resolution X-ray diffraction topography. The first article presents X-ray topography with a coherent beam to obtain structural information at domain boundaries in spatially-modulated crystals, the second deals with the in situ observation of the nucleation and propagation of the very first misfit dislocations in fully-strained epitaxial layers. Similarly, a novel technique based on rocking curve measurements using a CCD detector permits the rapid recording of rocking curves with high-spatial resolution. This new diagnostic tool is applied here to allow a better understanding of the relationship between the growth parameters, the distribution and impurity content and the crystalline perfection of synthetic-crystal diamonds. Another use of CCD detection is described in the article reporting the in situ 2-D and 3-D X-ray radiography of metal foams. The foaming behaviour of a liquid metal was observed in real-time.

The remaining articles demonstrate the effective application of a variety of microfocussing and imaging techniques; Micro-SAXS was used to study the structural reorganisation in single struts of elastomeric polyurethane foams as a function of strain under variable conditions. Another use of microdiffraction is reported in the study of the local-strain induced by submicrometre stripes of insulating oxide in a silicon substrate. X-ray imaging was applied to semiconductor technology showing that a full-field X-ray microscope can be used in transmission mode to image the electromigration process occurring into a passivated interconnect of a microelectronic device, with a resolution of 90 nm. Finally microfluorescence, a valuable technique used to map trace elements, was used to determine the intracellular distribution of iron and iodine within nuclei of pre-treated freeze-dried cells.