The x-ray Mv'Iv spectra of cerium and xenon.

Using a high-resolution curved crystal spectrometer of the Johann type with a fine focus x-ray source, the Mv'Iv absorption spectra of metallic cerium, cerium silicide, cerium fluoride, cerium oxide and xenon have been presented. Using the same spectrometer with a normal, point emission source, the Malpha, beta emission spectrum of cerium oxide has also been examined. For metallic cerium, by comparing the MV and MIV absorption lines obtained at 22 K with those obtained at room temperature, the mechanism of the y > alpha phase transition in cerium has been discussed. Cerium oxide was found to exhibit an anomalous MV, IV absorption spectrum. Two extra peaks, one connected with MV and the other with MIV have been observed to occur in the spectrum, A suggestion has been made to account for these features. Measurements on the MV, IV absorption spectra of oxidized metallic absorbers have indicated that cerium oxide (CeO2) results when the metal is oxidized in air, but oxidation in oxygen results in either Ce2O3 or a metallic sample covered with a protective layer of Ce2O 3. The measurement of MV, IV absorption in solid xenon has been performed and the resulting spectrum has been compared with that for the gas. The spectrum is dominated by two delayed, strong peaks arising from the transitions 3d > ef as for the gas. In the solid, in the region of strong peaks there are also observed remarkable modulations in the absorption coefficient which are discussed as EXAFS.