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[en] We present a study of the effects of interatomic multi-atom resonant photoemission monitored by soft X-ray emission. The C K_α partial fluorescence yield is measured while the excitation energy is scanned through the higher lying TiL_2,3 threshold of the neighboring atoms in a multi-component system (TiNbC). No evidence for a resonant enhancement in the fluorescence signal as suggested by the MARPE effect is found

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[en] Full text: We present a study of the 4d-4f giant resonance of Er³⁺ in Er₂O₃. The soft x-ray emission and absorption spectra are measured using tunable synchrotron radiation. We find strong resonant inelastic scattering with energy losses that can be assigned to excitations within the 4 f shell. We compare the measurements with our calculations as accomplished within the framework of the Kramers-Heisenberg formula for near-threshold inelastic scattering. The dipole-allowed transitions are calculated using Cowan's atomic multiplet code. Excellent agreement between theory and experiment is obtained, which indicates a highly atomic regime. We show that the 4f shell basis state label is a key selection criterion for the intermediate states. The results also show resonant mixing of intermediate states that are separated over a large energy range

[en] Single crystals of α-alumina were implanted with 380 keV Fe⁺ and Cu⁺ ions at a dose of 2.6x10¹⁷ cm^-2. The specimens were annealed at 1073 K for 1 and 96 h and the chemical state of the metal ions was investigated using soft X-ray fluorescence spectroscopy. Fe L_2,3 and Cu L_2,3 X-ray emission spectra (XES) excited by synchrotron radiation were measured at the Advanced Light Source (ALS) Lawrence Berkeley National Laboratory. It is found that the Fe L₂ to Fe L₃ XES ratio of iron-implanted alumina dramatically increased after annealing at 1073 K for 96 h, which is attributed to the formation of Fe₂O₃. On the other hand, we have found that the chemical state of Cu ions is rather stable to post-annealing and close to that of metallic copper

[en] The results of X-ray fluorescence measurements of niobium metal and its oxides (NbO, NbO₂ and Nb₂O₅) are presented. Non-resonant Nb M_4,5 and O Kα X-ray emission spectra (XES) have been measured at the Advanced Light Source (ALS, Berkeley). The experiments are compared with self-consistent band structure calculations of niobium metal and niobium oxides. We find the experimental spectra are consistent with band structure calculations of niobium metal and the oxides NbO₂ and Nb₂O₅. The difference between experimentally determined Nb M_4,5 XES of NbO and the calculated spectrum of Nb_1.0O_1.0 is understood on the basis of vacancies. We have mimicked the natural structure of NbO, which contains vacancies amounting to 25% in both sublattices. The electronic DOS of Nb_0.75O₇₅ is characterised by the formation of additional subbands connected with vacancy states. The calculated electronic structure based on this model is consistent with the XES measurements

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