Structure and reactivity of surface oxides on Pt(110) during catalytic CO oxidation

We present the first structure determination by surface x-ray diffraction during the restructuring of a model catalyst under reaction conditions, i.e., at high pressure and high temperature, and correlate the restructuring with a change in catalytic activity. We have analyzed the Pt(110) surface during CO oxidation at pressures up to 0.5 bar and temperatures up to 625 K. Depending on the O2/CO pressure ratio, we find three well-defined structures: namely, (i) the bulk-terminated Pt(110) surface, (ii) a thin, commensurate oxide, and (iii) a thin, incommensurate oxide. The commensurate oxide only appears under reaction conditions, i.e., when both O2 and CO are present and at sufficiently high temperatures. Density functional theory calculations indicate that the commensurate oxide is stabilized by carbonate ions (CO2−3). Both oxides have a substantially higher catalytic activity than the bulk-terminated Pt surface

Visions of Utopia: Sweden, the BBC and the Welfare State

Drawing on manuscripts and transcripts of BBC programme output, and material from the Radio Times, and the BBC’s The Listener magazine, this article analyses radio talks and programmes that focused on Sweden in the immediate years after the Second World War when the Swedish model was widely popularised abroad. The article argues that BBC output entangled domestic politics and transnational ideas around post-war reconstruction and welfare. Sweden was used as a lens through which a modern welfare state could be visualised and justified. This was however Utopia in two senses since the image of Sweden presented was in itself a highly idealised representation

Laue-DIC : a new method for improved stress field measurements at the micrometer scale

A better understanding of the effective mechanical behavior of polycrystalline materials requires an accurate knowledge of the behavior at a scale smaller than the grain size. The X-ray Laue microdiffraction technique available at beamline BM32 at the European Synchrotron Radiation Facility is ideally suited for probing elastic strains (and associated stresses) in deformed polycrystalline materials with a spatial resolution smaller than a micrometer. However, the standard technique used to evaluate local stresses from the distortion of Laue patterns lacks accuracy for many micromechanical applications, mostly due to (i) the fitting of Laue spots by analytical functions, and (ii) the necessary comparison of the measured pattern with the theoretical one from an unstrained reference specimen. In the present paper, a new method for the analysis of Laue images is presented. A Digital Image Correlation (DIC) technique, which is essentially insensitive to the shape of Laue spots, is applied to measure the relative distortion of Laue patterns acquired at two different positions on the specimen. The new method is tested on an in situ deformed Si single-crystal, for which the prescribed stress distribution has been calculated by finite-element analysis. It is shown that the new Laue-DIC method allows determination of local stresses with a strain resolution of the order of 10-5