Using linearly polarized synchrotron x rays with energies E=21.2 -43.7 keV, dift'erential cross sections for large-angle elastic photon scattering by Kr and Xe were measured. In the case of Xe, the energy region close to the K-shell binding energy (8~=34.561 keV) was investigated in detail.The experimental results agree well with theoretical predictions based upon the numerical energyshifted second-order S-matrix theory, and with high-energy-limit-corrected anomalous-scatteringfactor predictions.

Using monochromatized synchrotron radiation with variable photon energy E i = 33.94 keV... 34.54 keV, Resonant Raman Scattering (RRS) by free Xenon atoms (BI~ =34.566keV) was investigated. The measured double-differential RRS cross sections are in excellent agreement with those calculated in the non-relativistic dipole approximation, modified by some relativistic corrections, and including the interference corrections predicted by Tulkki and ~berg. Within the experimental error of 5 % the RRS cross section is found to be independent of the scattering angle and of the polarization of the incident photons.

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Using monochromatized synchrotron radiation with variable photon energy E i --43.01 ... 43.35 keV, Resonant Raman Scattering (RRS) by Neodymium atoms (K-shell binding energy Bls=43.57keV) was investigated. For the first time the fine structure splitting in a K-L-RRS spectrum due to the energy difference of the L 2 and L 3 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 nonrelativistic dipole approximation, modified by relativistic corrections.

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