Probe for spin- and valence-selective XAFS: EuLγ4

What is it about?

EuLγ4 emission spectra of EuS, EuF3, EuCl3, and Eu2O3 were measured using a multi-crystal, mult-idetector spectrometer. Splitting of the EuLγ4 band was observed in the EuS spectra and attributed to exchange interactions between Eu5p and Eu4f. It was shown that because of this splitting, the EuLγ4 emission could be used for performing spin-selective measurements. This emission exhibited a large chemical shift (∼5 eV), depending on the valence state of a compound. The applicability of this emission to valence-selective X-ray absorption fine structure spectroscopy was demonstrated through partial fluorescence yield measurements performed on a 1:1 mixture of EuS and Eu2O3 and on a valence-fluctuating compound Eu3Pd20Ge6.

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Why is it important?

The usefulness of EuLγ4 emission line, which has not been focused upon in recent X-ray studies, was demonstrated: it is applicable as a probe for selective XAFS spectroscopy. This finding can contribute to the characterization of Eu materials.