Photon-in/photon-out spectroscopy at the I20-scanning beamline at diamond light source.

A scanning multi-crystal x-ray emission spectrometer to perform photon-in/photon-out spectroscopy at the I20-Scanning beamline at Diamond Light Source is described. The instrument, equipped with three analyzer crystals, is based on a 1 m Rowland circle spectrometer operating in the vertical plane. The energy resolution of the spectrometer is of the order of 1 eV, having sufficient resolving power to overcome the core-hole lifetime broadening of most of the transition metals-edges.

Determination of the S-ZnO structural interaction in thiol-capped ZnO nanoparticles: a sulfur K-edge XAS study.

ZnO nanoparticles capped with thiol molecules display room temperature ferromagnetism which has been associated with the structural details of the interface formed between the organic molecule and the ZnO core. Although the local order around sulfur atoms at the ZnS/ZnO interface has been related to the occurrence of the ferromagnetic like behavior, no direct structural determination has been obtained yet. We report here a detailed x-ray absorption spectroscopy study performed at the sulfur K-edge to determine the local structure around the sulfur atoms in these systems and how it is modified by varying the length of the organic molecule.

EXAFS and XANES analysis of oxides at the nanoscale.

Worldwide research activity at the nanoscale is triggering the appearance of new, and frequently surprising, materials properties in which the increasing importance of surface and interface effects plays a fundamental role. This opens further possibilities in the development of new multifunctional materials with tuned physical properties that do not arise together at the bulk scale. Unfortunately, the standard methods currently available for solving the atomic structure of bulk crystals fail for nanomaterials due to nanoscale effects (very small crystallite sizes, large surface-to-volume ratio, near-surface relaxation, local lattice distortions etc.

Structural determination of Bi-doped magnetite multifunctional nanoparticles for contrast imaging.

To determine with precision how Bi atoms are distributed in Bi-doped iron oxide nanoparticles their structural characterization has been carried out by X-ray absorption spectroscopy (XAS) recorded at the K edge of Fe and at the L3 edge of Bi. The inorganic nanoparticles are nominally hybrid structures integrating an iron oxide core and a bismuth oxide shell. Fe K-edge XAS indicates the formation of a structurally ordered, non-stoichiometric magnetite (Fe3-δO4) phase for all the nanoparticles.

Magnetic disorder in diluted FexM100-x granular thin films (M=Au, Ag, Cu; x < 10 at.%).

Nanogranular thin films of Fe7Au93, Fe7Ag93 and Fe9Cu91 have been sputtered onto Si(100) substrates with the aim of studying the magnetic interactions. X-ray diffraction shows a major noble metal matrix with broad peaks stemming from (111) textured fcc-Au, Ag and Cu. The noble metal forms a nanogranular environment, as confirmed by transmission electron microscopy, with mean particle sizes below 10 nm.