Inelastic x-ray scattering from valence electrons near absorption edges of FeTe andTiSe2

Abstract

We study resonant inelastic x-ray scattering (RIXS) peaks corresponding to low-energy particle-hole excited states of metallic FeTe and semimetallic TiSe 2 for photon incident energy tuned near the L 3 absorption edge of Fe and Ti, respectively. We show that the cross-section amplitudes are well described within a renormalization-group theory where the effect of the core electrons is captured by effective dielectric functions expressed in terms of the the atomic scattering parameters f 1 of Fe and Ti. This method can be used to extract the dynamical structure factor from experimental RIXS spectra in metallic systems.

Explaining the x-ray nonlinear susceptibility of diamond and silicon near absorption edges

“…A similar term has been recently used to explain the enhancement of the cross section observed in the resonant inelastic x-ray scattering (RIXS) 18 . The factor η is derived by using the renormalization group method, that describes the variation of effective coupling constant under changes of scales [19][20][21] , and the method of dispersion relations applied to the atomic scattering factor.…”

Enhancement of Raman scattering from molecules placed near metal nanoparticles

“…In the RIXS theory, 1 ε can be evaluated by using firstprinciples calculations [9]. The model is then able to capture the overall amplitude of the RIXS signal.…”

“…For instance, the dimensionless coupling changes at the crossing of particle production thresholds in the standard model of particle physics [31]. Similarly, in materials such as FeTe or TiSe 2 [9], photons with energies near the 3 L absorption threshold produce virtual intermediate states involving a 2 p core hole and electron excited in a 3d state. In the case of SERS, the threshold energy is given by the plasmonic resonance of the metal nanoparticles.…”

“…This method is beyond perturbation theory and can take in account collision processes between light quanta and the elementary excitations of molecules at metallic surfaces. A similar approach has also been used to simplify the description of the resonant x-ray inelastic scattering (RIXS) for the particle-hole excitations [9]. Moreover, within the same scheme, one can derive an expression for the resonant term of the nonlinear susceptibility at x-ray edges [27].…”

“…In general the inelastic scattering cross section of photons is very small [9] and can be cast as the product of the Thomson scattering differential cross section Th / d d σ Ω with the dynamical structure factor ( , ) S ω q :…”