Suitability of polycapillary optics for focusing of monochromatic synchrotron radiation as used in trace level micro-XANES measurements

In this study a monolithic polycapillary half-lens was evaluated as a micro-focusing device for monochromatic synchrotron radiation. The tested optic produced an X-ray micro-beam of 37-53 microns in the energy range of 6-19 keV with a maximum intensity gain of about 600 with respect to the primary beam. When applied to X-ray fluorescence (XRF) analysis, absolute detection limits in the range of 0.06-1 pg were measured, coupled with relative detection limits of 0.3-200 ppm for the atomic number range of 20-40. The use of the polycapillary lens was demonstrated by performing microscopic X-ray absorption near edge structure (XANES) measurements in fluorescence mode on transition metals (concentration range 40-100 ppm) in fly ash particles.