X-ray fluorescence (XRF) is an analytical technique that can be used to determine the chemical composition of a wide variety of sample types including solids, liquids, slurries and loose powders. X-ray fluorescence is also used to determine the thickness and composition of layers and coatings. It can analyze elements from beryllium (Be) to uranium (U) in concentration ranges from 100 wt% to sub-ppm levels.

XRF is a robust technique, combining high precision and accuracy with straightforward, fast sample preparation. It can be readily automated for use in high-throughput industrial environments, plus XRF provides both qualitative and quantitative information on a sample. Easy combination of this ‘what?’ and ‘how much?’ information also makes rapid screening (semi-quantitative) analysis possible.

XRF is an atomic emission method, similar in this respect to optical emission spectroscopy (OES), ICP and neutron activation analysis (gamma spectroscopy). Such methods measure the wavelength and intensity of ‘light’ (X-rays in this case) emitted by energized atoms in the sample. In XRF, irradiation by a primary X-ray beam from an X-ray tube, causes emission of fluorescent X-rays with discrete energies characteristic of the elements present in the sample.

The technology used for the separation (dispersion), identification and intensity measurement of a sample’s X-ray fluorescence spectrum gives rise to two main types of spectrometer: wavelength dispersive (WDXRF) and energy dispersive (EDXRF) systems.