Spotlight on Science
Up one levelThe latest scientific news
Soft X-ray holographic microscopy
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 sam… (09-03-2010)
Bonding in high-pressure solid CO2 revealed by single-crystal diffraction
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 singl… (22-02-2010)
Ultrafast laser switching in a photochromic film visualised by time-resolved X-ray diffraction
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. … (22-02-2010)
X-ray beam transverse coherence analysis using near-field scattering
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.… (22-02-2010)
A different kind of memory in Ge-Sb-Te memory alloys
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… (13-01-2010)
Electronic structure of ligand orbitals revealed by valence-to-core X-ray emission
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 signat… (22-12-2009)
Studying atomic dynamics with coherent X-rays
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-r… (09-12-2009)
Stacking faults in colloidal photonic crystals revealed by microradian X-ray diffraction
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.… (23-11-2009)
How the genetic code is accurately translated into protein
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 imp… (12-11-2009)
3D Ordered gold strings by coating nanoparticles with mesogens
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 contro… (26-10-2009)
Local symmetries in disordered matter uncovered by coherent X-ray scattering
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 observ… (13-10-2009)
Circularly polarised X-rays as a probe of non-collinear magnetic order in multiferroic TbMnO3
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 mag… (01-10-2009)
An X-ray bilens nanointerferometer
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 overla… (11-09-2009)
Structure of metallic oxygen
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.… (31-08-2009)
Core-shell nanowires reveal their inner structure
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 a… (17-08-2009)
Molecular mechanism of bacterial survival against antimicrobial peptides revealed by X-ray studies
Lipopolysaccharides form the outer-most surface of Gram-negative bacteria, acting as the protector against chemical attack. Scientists have designed a model of bacterial surfaces at the air/water interface and solid/liquid interface, and then studied the impacts of ion species and cationic antimicro… (05-08-2009)
A novel nematic liquid crystal phase with ferroelectric response
Ferroelectric switching was observed for a nematic liquid crystal consisting of bent-core polar molecules. X-ray diffraction shows that this originates from the cooperative alignment of nanometric size polar and biaxial cybotactic groups present in the nematic phase. This discovery discloses the way… (06-08-2009)
A transfocator for X-ray focusing
A tunable X-ray focusing apparatus based on compound refractive lenses, referred to as a transfocator, has been installed in the first optics hutch of beamline ID11. By varying the number of lenses in the beam, the energy focused and the focal length can be varied continuously throughout a large ran… (14-08-2009)
Giant Kohn anomaly in the low-dimensional chain compound ZrTe3
A team of researchers from the ESRF has performed a careful combined diffuse and inelastic X-ray scattering study of a prototypical charge density wave material and found for the first time significant deviations from mean field theory in the lattice dynamics, reflecting directly the effect of the f… (16-06-2009)
The birth of micelles revealed by synchrotron light
Spontaneous micellisation of block copolymers in selective solvents was investigated by time-resolved SAXS experiments at the ESRF. The kinetic pathway of the micellisation was observed for the first time and could be modelled by a nucleation and growth process.… (26-05-2009)
Frankfurter Rundschau über Sternenstaub
Prof. John Rehr: seminar and practical on FEFF9