Particle Induced X-ray Emission (PIXE)

Particle-induced X-ray emission (PIXE) is a technique used to determine the elemental make-up of a material or sample. When a particle interacts with an atom,its electrons from inner electronic layer can be ejected. Other electrons from upper electronic levels will replace the missing ones, genereting X-rays. The energy of such X-rays depends on the nature of the atom. PIXE enables to identify and quantify chemical elements from Na to U for major, minor and trace elements, the latter meaning their quantity is at the ppm (part per million) scale. PIXE is a powerful yet non-destructive elemental analysis technique now used routinely by geologists, archaeologists, art conservators and others. By scanning the surface of the object with a focused ion beam 2D information about the elemental distribution can be achieved with micrometer spatial resolution in vacuum, circa 25 µm under helium atmosphere. In air, the the resolution is less favourable and some lighter elements cannot be detected by the method. On the other hand, the in-air set-up make it possible to analyse larger or sensitive objects. The elemental composition may indicate the provenance, manufacturing process and technology, workshop, date of production, authenticity, etc of the object.