Resonant Raman Scattering of synchrotron X-rays by neodymium: Observation of fine structure in K-L-RRS and of K-N-RRS

Using monochromatized synchrotron radiation with variable photon energyE _i =43.01...43.35 keV, Resonant Raman Scattering (RRS) by Neodymium atoms (K-shell binding energyB _1s=43.57 keV) was investigated. For the first time the fine structure splitting in a K-L-RRS spectrum due to the energy difference of the L₂ and L₃ subshells was observed. In addition, the first observation of K-N-RRS in the spectrum of scattered photons is reported. The measured double-differential RRS cross sections are, on an absolute scale, in very good agreement with those calculated in the non-relativistic dipole approximation, modified by relativistic corrections.