Disentangling the chemistry of Australian plant exudates from a unique historical collection

Non-resonant inelastic X-ray scattering for discrimination of pigments

Inelastic X-ray scattering (IXS) spectroscopy has been used in many fields of solid-state physics and theoretical chemistry as an accurate and quantitative probe of elementary excitations. We show that non-resonant IXS spectra in the energy loss range below 100 eV exhibit a strong contrast across a wide range of commercially available pigments, opening new routes for their discrimination. These signatures combine plasmonic transitions, collective excitations and low energy absorption edges. We have performed IXS to discriminate different artists' pigments within complex mixtures and to quantitatively determine rutile and anatase polymorphs of TiO2. The integration of experimental data on pigment powders with suitable ab initio simulations shows a precise fit of the spectroscopic data both in the position of the resonances and in their relative intensity.

X-ray Raman Scattering: A Hard X-ray Probe of Complex Organic Systems

This paper provides a review of the characterization of organic systems via X-ray Raman scattering (XRS) and a step-by-step guidance for its application. We present the fundamentals of XRS required to use the technique and discuss the main parameters of the experimental set-ups to optimize spectral and spatial resolution while maximizing signal-to-background ratio. We review applications that target the analysis of mixtures of organic compounds, the identification of minor spectral features, and the spatial discrimination in heterogeneous systems. We discuss the recent development of the direct tomography technique, which utilizes the XRS process as a contrast mechanism for assessing the three-dimensional spatially resolved carbon chemistry of complex organic materials. We conclude by exposing the current limitations and provide an outlook on how to overcome some of the existing challenges and advance future developments and applications of this powerful technique for complex organic systems.