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Polycapillary halflenses are widely used to focus X-ray radiation onto a small spot. Additionally they can reduce the field of view of a semiconductor detector when placed in front of one. In 3D micro X-ray fluorescence spectroscopy (3D Micro-XRF) with synchrotron radiation, two polycapillary halflenses are used in a confocal geometry. Up until now, characterization measurements in the focal plane have only been performed in the case of the lens focusing parallel radiation. Assumptions have been made, that in the other case, when isotropic radiation from a spot source is transported to a detector, the acceptance distribution in the focal plane is also Gaussian. We performed measurements with an electron beam as well as a proton beam which confirm this assumption. In addition, a comparison between measurements in collecting and focusing mode show differences in spot size and transmission. These differences exemplify the fact that there is not one global spot size or transmission function of a polycapillary halflens. Illumination and divergence effects can alter both characteristic lens parameters.
The investigation of an ancient Chinese ceramic served to further develop and validate fundamental parameter-based quantitation procedures in reference-free x-ray fluorescence (XRF) analysis. The XRF measurements of this sample were performed at the four-crystal monochromator beamline of the Physikalisch-Technische Bundesanstalt (PTB) at the BESSY II synchrotron radiation facility employing different excitation energies. The parallel processing of the XRF spectra recorded at different excitation energies provides a means to simultaneously evaluate relevant fundamental parameters and secondary enhancement processes such as those induced by photoelectrons. Employing well-characterized and absolutely calibrated instrumentation, all experimental parameters involved in XRF are known for small relative uncertainties allowing for a completely reference-free quantitation. Apart from traces of rare earth elements, the analytical results of the Chinese ceramic achieved by reference-free XRF are in line with target values given within a proficiency test of the International Atomic Energy Agency (IAEA) involving atomic and nuclear methods.