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Operando nuclear resonant inelastic X‐ray scattering (NRIXS) and X‐ray absorption fine‐structure spectroscopy (XAFS) measurements were used to gain insight into the structure and surface composition of FeCu and FeAg nanoparticles (NPs) during the electrochemical CO2 reduction (CO2RR) and to extract correlations with their catalytic activity and selectivity. The formation of a core–shell structure during CO2RR for FeAg NPs was inferred from the analysis of the operando NRIXS data (phonon density of states, PDOS) and XAFS measurements. Electrochemical analysis of the FeAg NPs revealed a faradaic selectivity of 36 % for CO in 0.1 M KHCO3 at −1.1 V vs. RHE, similar to that of pure Ag NPs. In contrast, a predominant selectivity towards H2 evolution is obtained in the case of the FeCu NPs, analogous to the results obtained for pure Fe NPs, although small Cu NPs have also been shown to favor H2 production. [ABSTRACT FROM AUTHOR]

Inelastic X‐ray scattering is a powerful and versatile technique for studying lattice dynamics in materials of scientific and technological importance. In this article, the design and capabilities of the momentum‐resolved high‐energy‐resolution inelastic X‐ray spectrometer (HERIX) at beamline 30‐ID of the Advanced Photon Source are reported. The instrument operates at 23.724 keV and has an energy resolution of 1.3–1.7 meV. It can accommodate momentum transfers of up to 72 nm−1, at a typical X‐ray flux of 4.5 × 109 photons s−1 meV−1 at the sample. A suite of in situ sample environments are provided, including high pressure, static magnetic fields and uniaxial strains, all at high or cryogenic temperatures. [ABSTRACT FROM AUTHOR]

Highlights the workshop on inelastic x-ray scattering, held on May 4-6, 2004 at Argonne National Laboratory in Chicago, Illinois. Purpose of the workshop; Keynote speakers; Topics discussed.

Abstract: Shear-aligned 40wt% calf-thymus Na-DNA molecules in aqueous solutions are prepared in their liquid crystalline phases and studied by high resolution inelastic X-ray scattering (IXS). Measured IXS spectra are analyzed with the generalized three effective eignmode (GTEE) theory. The phonon dispersion relations along the axial direction of DNA molecules with different MgCl2 concentrations are constructed and compared. It is found that the sound speed along the axial direction of DNA molecules varies only slightly, but the phonon dampening is greatly affected with the increase amount of MgCl2 concentration. Using the GTEE theory, we are able to extract the longitudinal viscosity in the hydrodynamic limit from the Q-dependence of a fitted parameter. We make a comprehensive review of the GTEE theory and discuss detailed analyses of IXS spectra taking into account finite energy resolution of the instrument. [Copyright &y& Elsevier]

We summarize a series of experimental results made with the newly developed high resolution X-ray scattering (IXS) instrument on two pure lipid bilayers, including dimyristoylphosphatidylcholine (DMPC) and dilauroylphosphatidylcholine (DLPC) in both gel and liquid crystal phases, and lipid bilayers containing cholesterol. By analyzing the IXS data based on the generalized three effective eigenmode model (GTEE), we obtain dispersion relations of the high frequency density oscillations (phonons) of lipid molecules in these bilayers. We then compare the dispersion relations of pure lipid bilayers of different chain lengths among themselves and the dispersion relations of pure lipid bilayers with those of the cholesterol containing bilayers. We also compare our experimental results with collective dynamics data generated by computer molecular dynamics (MD) simulations for dipalmitoylphosphatidylcholine (DPPC) in gel phase and DMPC in liquid crystal phase. [Copyright &y& Elsevier]