Monolithic polycapillary focusing optics and their applications in microbeam x-ray fluorescence

Monolithic polycapillary focusing optics cad collect a large solid angle of x rays from a point source and form intense focused beams for microbeam x-ray fluorescence (MXRF) analysis. Such an optic was tested and characterized in a MXRF setup. For the Cu K-alpha line, the measured 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), the average Cu K-alpha intensities over the focal spot was measured to be 8.9x10(4) photons/s/mu m(2). When compared to a straight single channel capillary optic with approximately the same output beam size, an intensity gain of 44 was obtained. ?The optic was applied to the MXRF setup to analyze trace elements in various samples and a minimum detection 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.