[en] Surface x-ray diffraction has been employed to elucidate the surface structure of TiO₂(110)(1x1). The atomic coordinates emerging from this study are in excellent agreement with those derived in other recent quantitative structure determinations of this surface. Most importantly, debate over the relaxation of the surface bridging oxygen has been resolved. In a previous surface x-ray diffraction study, it was concluded that this atom relaxes toward the bulk by 0.27±0.08 A, whereas in this present work we determined this displacement to be 0.10±0.04 A away from the bulk, which is in accord with the results of other experimental techniques

[en] We report here for the first time the combination of x-ray synchrotron light and a micro-electro-mechanical system (MEMS). We show how it is possible to modulate in real time a MEMS mass distribution to induce a nanometric and tunable mechanical oscillation. The quantitative experimental demonstration we present here uses periodic thermal dilatation of a Ge microcrystal attached to a Si microlever, induced by controlled absorption of an intensity modulated x-ray microbeam. The mechanism proposed can be envisaged either for the detection of small heat flux or for the actuation of a mechanical system.

[en] X-ray Magnetic Circular Dichroism (XMCD) spectra from a 5 μm polycrystalline Gd foil were measured in transmission across the Gd L_2,3 edges using the Multipurpose Unit for Synchronisation, Sequencing and Triggering (MUSST) card developed at the European Synchrotron Radiation Facility (ESRF). The circularly polarized x-rays were produced by a diamond phase-plate and their helicity was rapidly reversed through the use of a piezo driven device. The signal measured for each helicity was recorded by the MUSST card synchronized to the helicity reversal. The results are compared to those obtained using an analogue lock-in technique.

[en] The XMaS beamline at the ESRF has been in regular user operation since April 1998 and operates over an energy range of 2.4-15 keV. It has developed a wide range of unique instrumentation, primarily dedicated to high resolution magnetic and single crystal diffraction. With the upcoming ESRF upgrade program a number of instrumental developments are planned for the beamline to maximize the benefits of the increased photon flux at low energies. Firstly we report on the optimisation of the beamline and its core components. A novel attenuator system which is actuated by fast acting solenoids thereby avoiding problems of gas bursts into the beamline vacuum seen on some commercially available instruments is introduced. Secondly we discuss developments to the low temperature sample environments that have been integrated into the beamline vacuum system, minimizing both air and beryllium absorption. Finally we demonstrate the current capabilities of the beamline by describing preliminary reflectivity measurements that have been made on an [Fe(2ML)Pd(15ML)]x20 multilayer recorded around the Pd L₃ edge using circular polarised light produced from a thin diamond phase plate.

[en] Electron bombardment from a filament as well as voltage pulses from a scanning tunnelling microscope tip have been employed to modify the surface of TiO₂(110). Individual H atoms are selectively desorbed with electrical pulses of +3 V from the scanning tunnelling microscope tip, whilst leaving the oxygen vacancies intact. This allows us to distinguish between oxygen vacancies and hydroxyl groups, which have a similar appearance in scanning tunnelling microscopy images. This then allows the oxygen vacancy-promoted dissociation of water and O₂ to be followed with the microscope. Electrical pulses between +5 and +10 V induce local TiO₂(110)1 x 2 reconstructions centred around the pulse. As for electron bombardment of the surface, relatively low fluxes increase the density of oxygen vacancies whilst higher fluxes lead to the 1 x 2 and other 1 x n reconstructions

[en] A new materials characterization system developed at the XMaS beamline, located at the European Synchrotron Radiation Facility in France, is presented. We show that this new capability allows to measure the atomic structural evolution (crystallography) of piezoelectric materials whilst simultaneously measuring the overall strain characteristics and electrical response to dynamically (ac) applied external stimuli