http://www.esrf.eu The latest scientific news daily 1 2006-03-23T07:14:04Z http://www.esrf.eu/news/spotlight/spotlight102/spotlight102 Magnetic imaging with nanoscale domain resolution is now possible thanks to a new way of carrying out soft X-ray holography. The key feature of this microscopy-like imaging technique is a movable field-of-view that can be freely positioned on the sample. The microscope allows imaging of extended samples with some tens of nanometres resolution and provides chemical as well as magnetic contrast. 2010-03-09 07:45:00 No publisher admans 2010-03-09T07:54:34Z News Item http://www.esrf.eu/news/spotlight/spotlight101/spotlight101 Solid carbon dioxide undergoes a radical change from a molecular solid to a non-molecular “polymeric” state at elevated pressures and temperatures [1]. The polymeric state is characterised by the disappearance of the double bonds between the carbon and oxygen atoms and the formation of new single bonds. Whether this transformation occurs as a result of solid-state chemical reactions between molecules reaching a critical separation, or via intermediate states where molecules gradually distort as pressure increases, remains unknown. To solve this mystery, researchers from Université Pierre et Marie Curie have determined the structure of CO2 in the high-pressure phase IV, the ultimate molecular phase before its polymerisation into phase V. 2010-02-23 07:45:00 No publisher admans 2010-02-22T09:00:07Z News Item http://www.esrf.eu/news/spotlight/spotlight100/spotlight100 A [2+2] photo-cycloaddition reaction in an organic crystal film was triggered by a fast laser pulse and studied with X-ray diffraction. This reaction and its thermally-activated reverse reaction were followed on the picosecond timescale, and intricate details of the reaction kinetics were revealed. 2010-02-09 13:23:59 No publisher admans 2010-02-22T08:30:40Z News Item http://www.esrf.eu/news/spotlight/spotlight99/spotlight99 A new method to map the two-dimensional transverse coherence function of an undulator X-ray beam is proposed. It is based on near-field speckles generated by the interference between perfectly spherical scattered waves from a colloidal suspension and the partially coherent transmitted beam. 2010-01-26 14:52:21 No publisher admans 2010-02-22T08:30:25Z News Item http://www.esrf.eu/news/spotlight/spotlight98/spotlight98 Phase-change materials such as Ge-Sb-Te (GST) memory alloys are used in rewritable optical memory devices such as CDs and DVDs. In such applications, changes due to temperature are used to store data. But these materials also undergo structural transformation under pressure, with a surprising result on decompression. The structure “remembers” its initial form, either metastable cubic or stable hexagonal modification, as both exist under ambient conditions. 2010-01-13 13:59:33 No publisher admans 2010-01-13T13:29:07Z News Item http://www.esrf.eu/news/spotlight/spotlight97/spotlight97 The electron orbitals of ligands in 3d transition metal complexes can be studied by means of X-ray emission spectroscopy (XES). A comprehensive experimental and theoretical study of the X-ray emission from the valence band of Mn coordination complexes was carried out. The spectra provide a signature of the type of ligand and even permit a determination of the degree of ligand protonation. 2009-12-22 08:00:00 No publisher admans 2009-12-22T07:36:23Z News Item http://www.esrf.eu/news/spotlight/spotlight96/spotlight96 Solids may not be as stationary at the atomic level as they appear to be when viewed at the macroscopic scale. At only slightly elevated temperatures, the atoms already begin to exchange their places. Recently, this diffusion of a solid's atoms was measured for the first time using coherent X-rays, opening vast new possibilities for the study of the dynamics of solid matter. 2009-12-08 16:41:35 No publisher admans 2009-12-09T13:37:15Z News Item http://www.esrf.eu/news/spotlight/spotlight95/spotlight95 The presence of a network of intersecting stacking faults in self-assembled colloidal crystals was demonstrated with X-ray diffraction with microradian resolution. These defects can seriously affect the optical properties of photonic materials fabricated using colloid self-assembly. 2009-11-24 07:45:00 No publisher admans 2009-11-23T10:05:56Z News Item http://www.esrf.eu/news/spotlight/spotlight94/spotlight94 The production of proteins is performed in all organisms by ribosomes, nanomachines that carry out the translation of an mRNA sequence and the subsequent synthesis of a protein from that sequence. Ensuring that the genetic code is correctly translated into a functional protein is one of the most important steps that ribosomes perform in protein synthesis. A new crystal structure of the ribosome, in complex with an elongation factor, reveals how the ribosome guarantees that the genetic code has been correctly recognised before allowing peptide synthesis to occur. 2009-11-10 07:45:00 No publisher admans 2009-11-12T10:31:00Z News Item http://www.esrf.eu/news/spotlight/spotlight93/spotlight93 Gold nanoparticles associate into highly-ordered structures when coated with ligands formed from mesogens, the rigid part of a liquid-crystal molecule. The nanoparticles no longer follow the usual packing of spheres and form columnar structures, strings, with interparticle spacing that can be controlled by the choice of co-ligand. 2009-10-27 07:45:00 No publisher admans 2009-10-26T07:09:37Z News Item http://www.esrf.eu/news/spotlight/spotlight92/spotlight92 Local symmetries in colloidal glasses were investigated by coherent X-ray scattering. The speckle patterns were analysed by a novel angular cross correlation technique to unravel the hidden local symmetries within the glassy disorder. Four-, 6-, 10- and most prevalently 5-fold symmetries were observed pointing towards locally-favoured structures of icosahedral symmetry. 2009-10-13 06:45:00 No publisher admans 2009-10-13T06:43:27Z News Item http://www.esrf.eu/news/spotlight/spotlight91/spotlight91 A circularly polarised incident beam for non-resonant X-ray magnetic scattering together with full polarisation analysis of the diffracted beam has allowed ESRF scientists to shed light on the complex non-collinear magnetic structure of multiferroic TbMnO3, a challenging test case due to its two magnetic sublattices. A key feature of this study was the ability to control the population of the cycloidal magnetic domains by the application of an electric field. 2009-09-29 09:12:12 No publisher admans 2009-10-01T08:56:22Z News Item http://www.esrf.eu/news/spotlight/spotlight90/spotlight90 A novel type of hard X-ray interferometer employing a bilens system with two parallel arrays of compound refractive lenses has been developed by scientists from France and Russia. Under coherent illumination, the bilens generates two diffraction limited mutually coherent beams. When the beams overlap they produce an interference pattern with a fringe spacing ranging from tens of nanometres to tens of micrometres. This simple way to create a X-ray standing wave in a paraxial geometry opens up the opportunity to develop new X-ray interferometry techniques to study natural and advanced man-made nanoscale materials, such as self-organised biosystems, photonic and colloidal crystals, and nanoelectronic materials. 2009-09-15 06:45:00 No publisher admans 2009-09-11T15:49:42Z News Item http://www.esrf.eu/news/spotlight/spotlight89/spotlight89 Solid oxygen undergoes an insulator to metal transition at 96 GPa. Scientists investigated the structural changes that accompany metallisation using single crystal X-ray diffraction. 2009-09-01 06:45:00 No publisher admans 2009-08-31T09:25:01Z News Item http://www.esrf.eu/news/spotlight/spotlight88/spotlight88 Nature creates the most complex structures by assembling single atoms or molecules into functional building blocks. Semiconductor physics has been exploring this “self-assembly” phenomenon for several decades. An interesting example is self-assembled core-shell nanowires, where the nanowires are surrounded by a radial shell consisting of a higher band gap material. Using advanced X-ray structural characterisation techniques, scientists deduced the average shape, chemical composition, and strain field of core-shell nanowire ensembles. 2009-08-18 06:45:00 No publisher admans 2009-08-17T08:03:16Z News Item