A silicon phase retarder for producing circularly polarized x-rays in the 2.1-3 keV energy range

摘要

Circularly polarized synchrotron light is routinely used to study different material properties but is difficult to generate reproducibly below 3.1 keV. We present data from a 5 μm Si phase retarder (PR) designed to operate in the 2.1 to 3 keV energy range. Measurements were performed at the Pd L₃ edge to enable direct comparison with a conventional diamond PR. The degree of circular polarization was ascertained indirectly by recording the resonant specular reflectivity from a [Fe(2 ML)/Pd(15 ML)]_×20 multilayer. Our findings show that such a device can be used to extend the usable energy capability of PR technology down to 2.1 keV.