Angular and dynamical properties in resonant inelastic x-ray scattering: Case study of chlorine-containing molecules

Abstract

Polarization-dependent resonant inelastic x-ray scattering (RIXS) has been shown to be a probe of molecularfield effects on the electronic structure of isolated molecules. In this experimental analysis we explain the linear dichroism observed in Cl 2p polarized RIXS following Cl 1s excitation of a series of chlorofluoromethanes (CF 3 Cl, CF 2 Cl 2 , CFCl 3 , and CCl 4 ) as due to molecular-field effects, including singlet-triplet exchange. We present an approach to extract directly the 2p inner-shell electronic state populations from the experimental measurements. Using the angular properties of the measured KV emission we also are able to determine the value of the polarization anisotropy parameter β p for each resolved component of the KV emission spectra.

A new method to derive electronegativity from resonant inelastic x-ray scattering

“…We have shown recently that radiative KL decay in various chlorinecontaining compounds, specifically the Cl 1s −1 → 2p −1 transition following resonant excitation of a Cl 1s electron into the LUMO, exhibits complex structure and linear dichroism. [35][36][37][38][39][40] A schematic representation of the present RIXS experiments is shown in Fig. 1.…”

Thomson-resonant interference effects in elastic x-ray scattering near the Cl K edge of HCl

“…9,15,29 One significant modification is that the gas-sample cell now has a single silicon-nitride window oriented at 50 • with respect to the incident x-ray beam that functions as both an entrance and an exit window for the incident and scattered x-rays. This geometry minimizes selfabsorption by the sample, a condition required for accurate measurements of elastic scattering.…”

“…Hence, the incident light is highly linearly polarized (more than 99%), and the spectrometer effectively acts as a polarimeter for the scattered x-rays. 15 Two complementary geometries were achieved by rotating the spectrometer with respect to the gas cell and the remainder of the apparatus: (1) the parallel geometry, in which the polarization vectors of the incident and scattered x-rays, e 1 and e 2 , lie along the same axis; and (2) the perpendicular geometry, in which e 1 and e 2 are 90 • to one another. The RXS spectra are then collected by tuning the x-ray spectrometer to the elastic-scattering energy region and performing measurements as a function of the incident energy for the two geometries.…”

“…Over the past few decades, with the advent of newgeneration x-ray sources and detectors, the technique of resonant x-ray scattering (RXS) has developed from fundamental pioneering studies 1-4 into a powerful tool that is now used regularly to study atoms, 5, 6 molecules, [7][8][9][10][11][12][13][14][15] liquids, 16,17 solids, 18,19 buried interfaces, and even complex multi-component systems with practical applications, e.g., solar cells. 20 By itself, the use of x-rays yields the advantage of chemical sensitivity because the primary interactions are with core electrons, which are tightly bound to specific elements in a sample and easily distinguishable by their binding energies.…”

“…20 By itself, the use of x-rays yields the advantage of chemical sensitivity because the primary interactions are with core electrons, which are tightly bound to specific elements in a sample and easily distinguishable by their binding energies. At a fundamental level, the well-known KramersHeisenberg formalism 21 allows for a detailed understanding of RXS phenomena such as nonlinear dispersion, 7,13,14 electronic state lifetime interference, 10 polarization of molecular fluorescence, 8,9,15 etc. Within this framework, resonant Raman and non-resonant Thomson contributions must be included explicitly in order to understand and quantitatively analyze elastic x-ray-scattering measurements.…”