What is X-ray fluorescence (XRF)?

X-rays form part of the electromagnetic spectrum. They are on the high energy side of ultraviolet,  and are expressed in terms of their energy in kilo electron volts (keV), or wavelength in nanometers (nm).  X-ray fluorescence (XRF) can typically analyse elements from sodium to uranium, in concentrations ranging from parts per million to high percents, in solids, liquids, and powders.Part of the electromagnetic radiation spectrum
The elements and concentrations that XRF analysers can determine depend on the material being tested, and the instrument used.

How does X-ray fluorescence work?

How does X-ray fluorescence work?All XRF instruments are designed around two major components: an x-ray source (commonly an x-ray tube), and a detector.
Primary x-rays are generated by the source and directed at the sample’s surface, sometimes passing through a filter to modify the x-ray beam.
When the beam hits the atoms in the sample, they react by generating  secondary x-rays that are collected and processed by a detector.
The x-rays emitted by the atoms in the sample are collected by a detector, and processed in the analyser to generate a spectrum showing the x-rays intensity peaks versus their energy.
The peak energy identifies the element and its peak area (or intensity) gives an indication of its amount in the sample.
Spectrum showing the x-rays intensity peaks versus their energy
The analyser then uses this information to calculate the sample’s elemental composition.
The whole process, from pressing a start button or a trigger, to getting the analysis results, can be as quick as 2 seconds, or it can take several minutes.
It all depends on the instrument used, the range of elements measured, and the concentrations of those elements.
The energy of the emitted x-ray is characteristic of the elementThe energy of the emitted x-ray is characteristic of the element.
This means that XRF provides qualitative information about the sample measured.
However, XRF is also a quantitative technique.
What happens to the atoms in the sample during the analysis?
A stable atom is made of a nucleus and electrons orbiting it.
The electrons are arranged in energy levels or shells (K, L, M, N) and different energy levels can hold different numbers of electrons.
When a high energy primary x-ray collides with an atom, it disturbs its equilibrium.
An electron is ejected from a low energy level, and a vacancy is created, making the atom unstable.
To restore stability, an electron from a higher energy level falls into this vacancy and the excess energy released as the electron moves between the two levels is emitted in the form of a secondary x-ray.
Applications Notes

Application Note: Direct measurement of Phosphorous content in NIP coatings by X-ray Fluorescence 420.11 KB

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Application Note: Precise Analysis of Gold Alloys 108.42 KB

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Application Note: Thin Au in ENEPIG coatings 80.43 KB

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Application Note: X-MET8000 portable XRF analyser for the rapid, non-destructive analysis of electroless nickel coatings on steel 476.93 KB

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Application Note: X-MET8000 Series for high temperature applications 930.84 KB

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Application Note: X-MET8000 Series For Rapid Analysis of Welds and Welding Materials 431.71 KB

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Application Note: X-MET8000 Series For Rapid Flow Accelerated Corrosion Inspection 445.73 KB

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Application Note: X-MET8000 Series for rapid, on-the-spot coating thickness measurement 735.22 KB

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Applications Note: X-MET8000 for the analysis of Pt, Pd and Rh in catalytic converters 1.00 MB

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    Articles

    Article: The Electroless Nickel Plating Process and Its Importance (Quality Magazine) 127.37 KB

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    Article: "On-The-Go Tools for the Modern-Day Materials Analysis Expert" (Quality Magazine) 44.04 KB

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    Article: "Avoid costly process failures by utilizing XRF analysis" (Quality Magazine) 499.06 KB

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    Article: “Latest advances in portable elemental analysers” (Recycling International) 546.82 KB

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      Case Studies

      Case Study: Air crash investigation using Oxford Instruments handheld analysers 907.86 KB

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      Case Study: X-MET8000 Expert in archaeometry, conservation and restoration – Ashmolean Museum, Oxford 702.49 KB

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        Christelle
        Handheld XRF Expert

        Christelle is our handheld XRF expert. If you have any questions or comments about XRF please ask our experts.

        Matt K
        Benchtop XRF Expert

        Matt K is our benchtop XRF expert. If you have any questions or comments about XRF please ask our experts.