A four-point crystal bender for dispersive X-ray absorption spectroscopy

A new crystal bender for dispersive X-ray absorption fine-structure spectroscopy (XAFS) has been built and its performance characterized. The bender employs an adjustable four-point bending mechanism and a contoured crystal, which makes it possible to produce an excellent approximation of the ideal elliptical bend from 8000 to 20000 eV with a single such Si (220) crystal. With the near-elliptical optics, it is possible to achieve a focus size of 175 μm with a 5 mm source and simultaneously to achieve a useful bandpass of 700 at 9000, 1200 at 11500 and 2000 eV at 18000 eV. The upper limit on the resolution, which is dictated by the finite source size in this configuration, is 2–5 eV for all of the energy ranges studied.