MICRO-XAS USING TAPERED CAPILLARY CONCENTRATING OPTICS

Tapered capillary optics are a promising choice for producing micro-be ams at third generation sources. The reproducible energy dependence of their X-ray transmission, and fixed output beam position make them we ll suited for micro-XAS applications. Fiber optics techniques have bee n developed to produce long (1 m) capillaries which provide a good mat ch to the low divergence undulator beams at third generation sources. The results of X-ray tests made at the NSLS indicate the performance o f many of the capillaries closely match theoretical values. Currently these provide a monochromatic beam of about 10(6) ph/sec/mu m(2) at an unfocused bending magnet beamline. High quality X-ray images and micr o-XAFS have been obtained at the NSLS with better than 3 mu m resoluti on. The same capillaries should provide more than 10(10)ph/sec/mu m(2) at an APS undulator, indicating that sub-mu m XAS is possible.