Seminars Archive

Multilayer Transmission Filters for Soft X-ray Polarimetry

Abstract
Since the development of synchrotron sources of third generation, there is an increasing interest in the use of circularly polarized light by research groups from biology (structure of organic chiral molecules) to materials science (magnetic circular dichroism). In order to unambiguously characterize in these experiments the polarization state of the probing photon beam one needs to use a polarizer and an analyser. The polarizer introduces a phase retardation in one of the two orthogonal components (s-p) of the electromagnetic wave, while the analyzer transmits preferentially only one of these components. While up to 100 eV photon energy the optimum 90 degrees phase retardation can be achieved in transmission and multiple reflection polarizers, above this energy only multilayer transmission filters have shown to provide some phase retardation. For several years already the multilayer group of ELETTRA, in collaboration with colleagues from BESSY, is involved in pioneering studies for phase retarders in this energy range. In the seminar the performance of such objects produced at ELETTRA and in other collaborating laboratories will be discussed. Their successful application for the characterization of the polarization behind soft x-ray monochromators will be presented with data obtained very recently with the first beam from the circularly polarized beamline at ELETTRA.