Fluorescence yield carbon K edge soft x-ray absorption measurements of mixed element samples are impeded by background scattered x-rays and fluorescence from non carbon atoms within the sample induced by the incident x-ray beam (first and higher orders). We describe a high efficiency near-normal incidence focusing multilayer mirror detection system for carbon K edge fluorescence yield softx-ray absorption spectroscopy. A spherical focusing multilayer mirror collects nearly 60 % of the available solid angle with a reflectivity of 6 % and a resolution of 2 % (dE/E) for carbon K radiation in combination with a high efficiency proportional counter detector. The focusing multilayer system is able to effectively discriminate the background fluorescence and scattered light signals originating at the sample during a carbon K edge soft x-ray absorption experiment. A signal to background ratio in excess of 100 is possible for very dilute carbon samples, enabling a whole new class of in-situ photon-in photon-out soft x-ray absorption measurements of carbon chemistry in catalysts to be made, even in a reactive chemical environment.
Citation: Review of Scientific Instruments
Issue: No. 3
Pub Type: Journals
detectors, multilayers, NEXAFS, soft x-ray