MONOLITHIC POLYCAPILLARY FOCUSING OPTICS AND THEIR APPLICATIONS IN MICROBEAM X-RAY-FLUORESCENCE

Monolithic polycapillary focusing optics cad collect a large solid ang le of x rays from a point source and form intense focused beams for mi crobeam x-ray fluorescence (MXRF) analysis. Such an optic was tested a nd characterized in a MXRF setup. For the Cu K-alpha line, the measure d focal spot size of the optic was 43 mu m full width at half-maximum (FWHM). With the 16 W microfocusing x-ray source (50 mu mx10 mu m), th e average Cu K-alpha intensities over the focal spot was measured to b e 8.9x10(4) photons/s/mu m(2). When compared to a straight single chan nel capillary optic with approximately the same output beam size, an i ntensity gain of 44 was obtained. ?The optic was applied to the MXRF s etup to analyze trace elements in various samples and a minimum detect ion limit (MDL) of about 2 pg was achieved for the transition elements (V, Cr, Mn, and Fe). The optic was also used to map the distributions of trace elements in various samples. (C) 1996 American Institute of Physics.