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

Abstract

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.

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

“…29 IXS relies on the energy and momentum transfers measured from a high-energy incident photon in the X-ray range that is defined by its wave vector, energy, and polarisation ( k 1 , ħω 1 , ε 1 ) by the electron system and the scattered photon ( k 2 , ħω 2 , ε 2 ) defined by the same parameters. 30,31 The measured energy transfer ħω is given by the law of conservation of energy, ħω = ħω 1 − ħω 2 and momentum transfer q is a function of the scattering angle. The number of photons being measured in a certain energy range is defined by the double differential scattering cross-section (DDSCS),where according to Fermi's Golden rule and under first-order perturbation theory, the probability of the transition from a ground state to a final state can be described; on one hand, it is related to Thomson scattering, associated with the strength of photon–electron coupling and, on the other hand, it is related to the strength of the DSF S ( q , ω ), which is directly related to the allowed excitations of the scattering system.…”

“…29 IXS relies on the energy and momentum transfers measured from a high-energy incident photon in the X-ray range that is defined by its wave vector, energy, and polarisation (k 1 , h o 1 , e 1 ) by the electron system and the scattered photon (k 2 , h o 2 , e 2 ) defined by the same parameters. 30,31 The measured energy transfer h o is given by the law of conservation of energy,…”

5f covalency from x-ray resonant Raman spectroscopy

“…A third instance of this is x-ray Raman scattering (XRS) and its resonant variant, x-ray resonant Raman scattering (XRRS). While XRS is more typically associated with organic and inorganic systems [11][12][13] there is already a history of XRRS [14] with uranium compounds, specifically UR 2 Si 2 [15]. Here, XRRS measurements made at the U M 5 edge will be presented.…”

Mechanisms underlying the acid leaching process for LiNi0.6Co0.2Mn0.2O2 with and without H2O2

“…XRS utilizes the inelastic scattering of hard X-rays, providing information equivalent to that of soft XAS under the dipole approximation. [14][15][16] Because hard X-rays penetrate deeper, XRS conveys information on X-ray absorption edges in the bulk material, whereas soft XAS provides surface information (within B50 nm). We selected LiNi 0.6 Co 0.2 Mn 0.2 O 2 (NCM622) as a model because of its increasing popularity as a positive electrode material for high-energy-density LIBs.…”