Application of polycapillary optics to x-ray fluorescence for advanced spectroscopy and microscopy studies

Advances in x-ray techniques, including x-ray optics, have paved the way to obtain challenging results in several research fields thanks to the improvement in terms of spatial resolution. This is particularly true for x-ray fluorescence (XRF), where the combination of conventional x-ray sources with polycapillary optics has permitted to have high flux and high focused beams. However, XRF spectroscopy applied to archeological samples at a lab scale is mainly dedicated to qualitative studies. At the same time, quantitative analysis still remains a strong hurdle mainly due to important matrix effects that affect the signal related to the chemical components under evaluation. In this respect the adoption of x-ray optics on both the source and the detector represents a way to improve the signal to noise ratio, necessary for quantitative analysis. At LNF XLab Frascati the expertise, gained on x-ray techniques and on polycapillary lenses, has allowed researchers to carry out advanced μXRF studies. RXR (Rainbow X-ray), is the experimental station dedicated to 2D/3D XRF micro-imaging and TXRF analysis, being equipped with 2 detectors of different energy efficiency (covering a full spectrum from 800 eV to 25 keV) and working in confocal mode with the source coupled with a full-lens and both the detectors combined with dedicated half-lenses. This report aims in depicting the RXR potentialities through the results obtained in 2 case studies dedicated to carry out a semi-quantitative analysis of 2 different artifacts (an ancient book, a Buddhist scroll) by μXRF characterization.