Highly sensitive non-destructive rare earth element detection by means of WD-XRF spectroscopy enabled by an energy dispersive pnCCD detector

Detection of rare earth elements (REE) is commonly performed with destructive techniques such as (LA)-ICP-MS or coupled to a destructive sample preparation. When investigating unique geological samples, such as cometary, asteroidal or interstellar material from sample return missions or inclusions in deep-Earth diamonds, a non-destructive method is preferred. The presented non-destructive highly sensitive wavelength-dispersive X-ray fluorescence spectroscopy (WD-XRF) technique is designed to measure the L-lines of REE between 4.5 and 7 keV with a sensitivity down to the ppm level. REE fluorescence L- lines are often only separated by a few eV from neighboring XRF lines and cannot be resolved by an energy dispersive approach especially in the presence of transition metal K lines. In our spectrometer the characteristic X-rays emitted by the sample are dispersed by a fixed Ge(111) analyzer crystal over the active area of an energy dispersive pnCCD detector, enabling high energy resolution detection of X-rays...