No abstract

Resonant inelastic X-ray scattering spectra at the iron L-edge from hemin in dimethyl sulfoxide liquid solution are reported. Our experiments, which are interpreted with the help of electronic structure calculations, support earlier assignments of hemin-solvent interactions, including the iron spin state and the role of the chloride ligand obtained from a total fluorescence yield study. The analysis of the explicit radiative relaxation channels of 2p core-level excited iron, explored in the present work, allows for a rather quantitative assignment of the orbitals involved in the excitation-deexcitation process of the core-excited hemin in solution. We specifically distinguish between contributions of partially and fully occupied valence orbitals to the broad X-ray emission band. In addition, our calculations reveal a detailed picture of the character of these orbitals.

Laterally periodic nanostructures were investigated with grazing incidence small angle X-ray scattering (GISAXS) by using the diffraction patterns to reconstruct the surface shape. To model visible light scattering, rigorous calculations of the near and far field by numerically solving Maxwell's equations with a finite-element method are well established. The application of this technique to X-rays is still challenging, due to the discrepancy between incident wavelength and finite-element size. This drawback vanishes for GISAXS due to the small angles of incidence, the conical scattering geometry and the periodicity of the surface structures, which allows a rigorous computation of the diffraction efficiencies with sufficient numerical precision. To develop dimensional metrology tools based on GISAXS, lamellar gratings with line widths down to 55 nm were produced by state-ofthe-art e-beam lithography and then etched into silicon. The high surface sensitivity of GISAXS in conjunction with a Maxwell solver allows a detailed reconstruction of the grating line shape also for thick, non-homogeneous substrates. The reconstructed geometrical line shape models are statistically validated by applying a Markov chain Monte Carlo (MCMC) sampling technique which reveals that GISAXS is able to reconstruct critical parameters like the widths of the lines with sub-nm uncertainty.

Colloidal dispersion is essential for most nanodiamond applications, but its influence on nanodiamond electronic properties remains unknown. Here we have probed the electronic structure of oxidized detonation nanodiamonds dispersed in water by using soft X-ray absorption and emission spectroscopies at the carbon and oxygen K edges. Upon dispersion in water, the π* transitions from sp(2)-hybridized carbon disappear, and holes in the valence band are observed.