A wide-aperture dynamically focusing sagittal monochromator for X-ray spectroscopy and diffraction

Abstract

A scanning dynamically focusing sagittal X-ray monochromator accepting 7 mrad of the fan from a 6 T wiggler is in routine use on beamline 16.5 (ultra-dilute spectroscopy) of the SRS at CCLRC Daresbury Laboratory, UK. The energy range covered is 7-27 keV, with a horizontal spot size of <1.1 mm FWHM. Measured monochromatic flux from a Si 220 crystal pair is 1 x 10(11) photons s(-1) (100 mA)(-1) at 9 keV. This level of flux, usually associated with an insertion device on a third-generation source, permits collection of EXAFS data on concentrations at or below 10 ppm.