Reference-Free XRF - Principle, Calibrated Instrumentation and Spectra Deconvolution

The Physikalisch-Technische Bundesanstalt operates its own laboratory1 at the electron storage ring BESSY II in Berlin. One major task of this laboratory, hosting the departments Radiometry and X-ray Metrology with Synchrotron Radiation, is the use of well-defined synchrotron radiation for calibration of different types of detectors in the spectral range from UV/VUV to the harder X-ray range. Well-known radiation sources in conjunction with calibrated instrumentation are used for X-ray fluorescence analysis (XRF) allowing for completely reference-free quantification. Here, the XRF spectra deconvolution with experimentally determined detector response functions and the further improvement of it by using line-sets for each subshell of an involved element has been developed. Synchrotron radiation originating from a bending magnet can be partially seen as an equivalent to the solar emission spectrum in the soft and hard X-ray range. Using different electron energies in the storage ring of BESSY II as well as of PTB's own Metrology Light Source (MLS), different parts of the solar spectrum can be approximated allowing for complementary simulations of excitation conditions for XRF remote sensing of planetary surfaces.