Proton Induced X-ray Emission (PIXE)
Proton induced x-ray emission (PIXE) was first introduced at the Lund Institute of technology in 1970. PIXE is a technique which can be used for non-destructive, simultaneous elemental analysis (Sodium through Uranium) of solid, liquid, thin film, and aerosol filter samples. (See Examples) Like other spectroscopic techniques used for elemental analysis, PIXE is based upon the physics of the atom, not its chemistry. It involves both the excitation of the atoms in the sample to produce characteristic X-rays and a means of detection, in order that their intensities may be identified and quantified. |
 PIXE Limits of Detection (LODs) Detection Limit Comparison of Various Filter Media for PIXE Analysis |
However, the use of proton beam as an excitation source offers several advantages over other X-ray techniques. Among these are:
- Higher rate of data accumulation across the entire spectrum which allows for faster analysis
- Better overall sensitivities, especially for the lower atomic number elements
This is due to a lower Bremsstrahlung background resulting from the deceleration of ejected electrons, as compared to electron excitation; and the lack of a background continuum, as compared to XRF analysis. Because of the ever increasing need for elemental analysis of very small sample amounts (e.g. 0.1g - 1 mg), as in the case with aerosol filters, the PIXE technique has rapidly gained acceptance as a valuable analytical tool.
When samples are bombarded with the beam, the protons interact with the electrons in the atoms of the sample, creating inner shell vacancies. The energy of the X-rays emitted when the vacancies are refilled are characteristic of the element from which they originate, and the number of X-rays is proportional to the amount of the corresponding element within the sample.
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Industry Applications for PIXE
- *Activated Carbon: Manufacturers & Regenerated Carbons - Heavy Metals & Others
- *Adhesives & Sealants: QA/QC, R&D applications - Contaminants, Product Make-Up
- *Coal & Coal Products: Metals, Sulfur (also Power Plants for boiler residues, Flue-Gas Desulphurization)
- Brick & Refractories: QA/QC, Al, Si, Na, other metals
- Carbon & Carbon Graphite Products: Metals & other components
- *Catalysts: Manufacturers & Regenerated Catalysts- Precious Metals, other Metals
- Cement & Cement By-Products: Basic Constituents, Metals
- *Ceramics: QA/QC, Contaminants, Basic Constituents
- *Organic/Inorganic Pigments: QA/QC, Heavy Metals, Contaminants
- *Electronics & Semiconductors: QA/QC, Heavy Metals (see Industrial Hygiene below)
- Forensics: Gun Residues (Metals), Tissue Samples, Counterfeit Coins, Expert Witness Svcs.
- Foundries, Iron, Steel, etc.: QA/QC, Unknowns, Release Agents
- *Glass & Glass Products (lighting, coatings): Contaminants, Raw Materials, Manufacturing, Residues
- *Industrial Hygiene: Heavy Metals/Inorganics, Air Monitors/Samples, Wipe Samples
- *Lubricating Oils & Greases: Metals, Contaminants, Failure Analysis, Rev. Engineering
- *Metal Ores & Processing: Purity, Contaminants
- *Paints, Varnishes, Lacquers, Enamels: Contaminants, Unknowns, QA/QC
- *Paper Mills & Products: Process System Monitoring, Contaminants, Boiler Residues
- *Petroleum Products: Metals, Contaminants, QA/QC
- *Pharmaceuticals: QA/QC, R&D, Purity, Contaminants, Rev. Engineering
- *Plastics & Plastic Products: QA/QC, Purity, Contaminants
- Organic Based Resins & Polymers
- *Smelting & Refining of Metals & Precious Metals: Purity, Contaminants
- Stack Monitoring & Testing: Heavy Metals & Inorganic Constituents
- Storage Batteries & Components: Purity, Contaminants, QA/QC
- Surgical & Medical Instruments & Apparatus: Contaminants, QA/QC, Potential Liability
- *Synthetic Fibers, Rubber, & Elastomers: QA/QC, Purity, Contaminants, Reverse Engineering
- *Rubber & Rubber Products (Tires, etc.): Metals, Contaminants, QA/QC
- Wood Preserving & Products: Contaminants, Purity, Unknowns, QA/QC
- Yeasts & Yeast Products: Purity, Contaminants, Unknowns, QA/QC
* Denotes Excellent Potential *
