CHARACTERIZING METALLIC NANOPARTICLES BY X-RAY ABSORPTION SPECTROSCOPY: TWO NEW APPROACHES

X-ray absorption spectroscopy (XAS) is an extremely valuable tool for the characterization of the electronic and geometric properties of nanoparticles. However, there are drawbacks when it comes, for example, to time-resolved in situ measurements of wet-chemical synthetic reactions or when X-ray absorption near edge structure (XANES) spectra are used for characterizing atoms that occupy different sites in a nanoparticle. In this paper, we report results of test experiments using resonant inelastic X-ray scattering (RIXS) for obtaining high-resolution spectra that allow in principle site- and/or valency-specific XANES measurements. For a detailed analysis of wet-chemical reactions, a microreactor system is used in which time resolution is obtained by spatial resolution, i.e., by measuring spectra at various points along the microreactor. This system provides significantly better resolution (in the order of milliseconds) compared to conventional techniques.