X-ray imaging techniques at third-generation synchrotron radiation facilities are continuously providing original scientific results for a wide variety of scientific topics. This is reflected by the content of the present chapter, which includes contributions from areas ranging from biology and biomedical applications to environment, materials and cultural heritage.

New science often relies on new technical developments: most of the ESRF scientists devote a substantial part of their research to new developments. This has resulted in an extended, state–of-the-art portfolio of synchrotron radiation based X-ray imaging techniques. The present Upgrade Programme of the ESRF will lead to the most advanced versions of both nano-imaging and nano-analysis (UPBL4, NINA) and of coherent and parallel beam imaging, with special emphasis on palaeontological applications.

This effort towards new and improved techniques is exemplified by a contribution that describes the development of a new two-dimensional X-ray grating interferometer for biomedical applications. But the technical enhancements are also, implicitly, present in most of the other contributions, where the improvement in spatial (in the few tens of nm range) and temporal resolution (a complete microtomographic image with a recording time in the second range), as well as the increasing use of “tailored” pink beam for microtomographic purposes, appear to be key ingredients to reach the desired scientific results. Let us point out, in addition, the continuous progress of techniques combining imaging and Bragg diffraction, which allow the limitations of classical “diffraction topography” to be overcome. Examples resulting from this combination are given in recent publications. Scanning transmission X-ray image of the deformation structure inside a single grain in a polycrystalline Ni foil were, for instance, obtained at ID22 by using a submicrometre spot [1]. The combination of Bragg diffraction with a 3D approach [2] provided images allowing one to follow the inception of the deformation process of a grain in ice, as shown in the figure below, by the image corresponding to a “virtual slice” located in the middle of this crystal. This combination of diffraction and imaging also gives access to the study, in 3D, of the most deformed grains, which are of particular interest, by using the latest enhancements of the diffraction contrast tomography (DCT) technique [3].

figure_125_HL2011m.jpg

Fig. 125: a) Schematic drawing of the single grain of ice, indicating the central virtual slice which is at the origin of the images of the local FWHM values shown on b, c, and d; this virtual slice cuts the triple junction where three grains meet on T. b) Initial state of the ice crystal, exhibiting individual dislocations in a nearly perfect crystalline matrix. c) Intermediate state, after a first application of an external stress, showing slip bands. d) Final state, showing the inception of the formation of a subgrain boundary. Note that the scale, in arc seconds, is very different for the three images (Courtesy of A. Philip and J. Messonnier, LGGE Grenoble).

In the first section on biology and biomedical applications, the direct investigation of the localisation of antimalaria drugs in red blood cells was made possible by the spatial resolution, in the few tens of nm range, now available on ID22. This trend will be pursued through the NINA project, mentioned above. The second contribution to this section studies vessel resistance to microbeam radiation as a function of vascular maturation, which is of high importance in order to prepare the clinical applications of microradiation therapy (MRT), a technique that takes full advantage of synchrotron radiation’s characteristics. Finally, a non invasive virtual extraction of entire teeth by using synchrotron radiation based microtomography with a coherent beam allowed an insight into the evolutionary biology of special present-day mammals that display continuous dental replacement.

The second section on materials shows the same variety of applications, which range from the microtomographic study of the multiphase network providing high-temperature strength to metallic alloys of industrial interest, to the combined use of several X-ray imaging techniques to characterise structured catalysts, and to the nano X-ray absorption spectroscopy investigation of Co in ZnO nanowires. X-ray imaging is increasingly being used for cultural heritage studies. Synchrotron X-ray spectromicroscopy coupled with related methods, on ID21, allowed the degradation process of yellow pigment in Van Gogh paintings to be understood. Synchrotron radiation microtomography with a high energy and/or coherent beam makes it possible to reach elusive information that can completely change our understanding of a palaeontological subject. A very important study, performed at ID17, of the large fossil skull Australopithecus sediba, recently discovered in South Africa, and aged 1.9 million years, shows that whereas the brain volume is still the one of a typical Australopithecus, the anterior part of the brain already displays a complex reorganisation similar to that observed in the genus Homo. Another study, performed at ID19, led to evidence about the diet of one of the most important group of ammonites, distant relatives of squid, octopuses and cuttlefish, which sheds a new light on the reason for their extinction 65.5 million years ago.

All these investigations will be fostered by the refurbishment of the ID17 and ID19 beamlines, which aims to provide the palaeontological community with specially designed facilities, and, of course, these facilities will also be beneficial for many other scientific communities. The upgrade/refurbishment programme presently developing at the ESRF will provide new and unique opportunities on long beamlines both for imaging at high resolution of large samples (ID19, ID17), and for nano-imaging and nano-analysis on the new ID16 beamline (NINA).

J. Baruchel

 

 

References

[1] B. Abbey, F. Hofmann, J. Belnoue, A. Rack, R. Tucoulou, G. Hughes, S. Eve, A.M. Korsunsky, Scripta Materialia 64, 884–887 (2011).

[2] R.T. Kluender, A. Philip, J. Meyssonnier, J. Baruchel, Phys. Stat. Sol. A 208, 2505-2510 (2011).

[3] A. King, P. Reischig, S. Martin, J. Fonseca, M. Preuss, W. Ludwig, 31st Risö International Symposium on Materials Science, ed. N, Hansen et al. (2010).