XRF analysis stands for X-ray fluorescence analysis. It is a physical method to determine the kinds of elements and their amount in a sample by making use of the physical principles of the atomic structure. An element is characterised by its atomic nucleus with a corresponding number of protons and its enclosing shell with an identical number of electrons. The electron shell is divided into different orbitals resp. energy levels. In X-ray spectroscopy, they are designated continuously from the innermost outwards as K, L, M… K, the shell nearest to the nucleus, has the lowest energy, while the respective outermost shell shows the highest energy.
When an electron changes from a higher to a lower energy level, the difference in energy is emitted as X-rays characteristic for the particular element. This radiation, characteristic for the atom, is called X-ray fluorescence.
Due to physical principles, the fluorescence yield and energy of elements of low atomic numbers dwindle drastically. This is why the “lighter elements” Mg, Al, Si, P and S are more difficult to measure. XRF analysis works on metals, ceramics, soils, fluids, electric conductors or isolators. As a method, it is independent from the sample and delivers fast results.