Particle-induced gamma emission (PIGE) is a form of
nuclear reaction analysis, one of the
ion beam analysis thin-film
analytical technique Analytical technique is a method used to determine a chemical or physical property of a chemical substance, chemical element, or mixture. There is a wide variety of techniques used for analysis, from simple weighing to advanced techniques using high ...
s.
Technology
Typically, an MeV proton beam is directed onto a sample which may be tens of microns thick, and the fast protons may excite the target nuclei such that gamma rays are emitted. These may be used to characterise the sample. For example, sodium in glass is of great importance but can be hard to measure non destructively:
X-ray fluorescence
X-ray fluorescence (XRF) is the emission of characteristic "secondary" (or fluorescent) X-rays from a material that has been excited by being bombarded with high-energy X-rays or gamma rays. The phenomenon is widely used for elemental analysis ...
(XRF) and
particle-induced X-ray emission
Particle-induced X-ray emission or proton-induced X-ray emission (PIXE) is a technique used for determining the elemental composition of a material or a sample. When a material is exposed to an ion beam, atomic interactions occur that give off EM ...
(PIXE) are both sensitive only to the surface few microns of the sample because of the low energy (and consequent high absorption coefficient) of the Na K X-rays (1.05 keV). But, for example, the
23Na(p,p'γ)
23Na reaction has a high and relatively well-known cross-section
see the IAEA "IBANDL" site and is therefore frequently used for determining bulk sodium content of glasses, since the gamma energy (440 keV) is so high that there is effectively no absorption.
The
IAEA
The International Atomic Energy Agency (IAEA) is an intergovernmental organization that seeks to promote the peaceful use of nuclear energy and to inhibit its use for any military purpose, including nuclear weapons. It was established in 195 ...
has sponsored the development of a database of PIGE cross-sections.
Applications
PIGE has been used to detect total
fluorine as a screening tool for
PFAS
Per- and polyfluoroalkyl substances (PFASs) are synthetic organofluorine chemical compounds that have multiple fluorine atoms attached to an alkyl chain. An early definition, from 2011, required that they contain at least one perfluoroalkyl mo ...
.
References
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Medical imaging