Ion Beam Analysis - Proton Induced X-ray Emission
Overview[edit | edit source]
What it measures[edit | edit source]
Energetic protons can also eject inner-shell electrons and the subsequent electron transitions to fill the empty, inner shell orbitals also produce characteristic x-ray energies. Photons, electrons and protons lead to the production of characteristic energy x-rays that can be used to identify elements in pigments or in metallic artifacts.
Most common uses in conservation[edit | edit source]
analysis of manuscript ink, small statues, metallic plate, coins
Applications[edit | edit source]
In PIXE the proton beam irradiates a relatively small area of the artifact (beam sizes are approx. 1mm x 1mm down to 0.1mm x 0.1mm - the diameter of a paper clip wire or smaller) thus small enough to lie well within a line of ink on a manuscript or a well defined ara of a painting. Additionally one of the advantages of PIXE is that calibration of the amount of pigment is easier than with other techniques (e.g. XRF). PIXE (requires an ion acelerator which is a large, fixed piece of equipment and so unlike with XRF the painting or artifact must be brought to the equipment in the lab.