The Basic Process

The technology of the analyzer is based on energy dispersive X-ray fluorescence using an X-ray tube as the source of excitation. The range of detectable elements varies according to the individual instrument’s configuration, but typically EDXRF covers all elements from sodium (Na) to uranium (U). Concentrations can range from ‘100%’ down to ‘ppm’ (and in some cases sub-ppm) levels. Limits of detection depend upon the specific element and the sample matrix, but as a general rule, the heavier elements will have better detection limits.

X-ray fluorescence involves the emission of characteristic fluorescent X-rays from a material which has been excited by bombarding it with high-energy X-rays or gamma rays. X-ray fluorescence can be considered as a simple, three-step process occurring at the atomic level. First, an incoming X-ray knocks out an electron from one of the orbitals surrounding the nucleus within an atom of the material. A ‘hole’ is produced in the orbital, resulting in a high- energy unstable configuration for the atom. To restore equilibrium, an electron from a higher-energy, outer orbital falls into the hole. Since this is a lower-energy position, the excess energy is emitted in the form of a fluorescent X-ray. This is the ‘Energy Dispersive’ aspect of the process and it is this energy which is measured by the equipment.

xrf-excitation-model

The difference in energy between the expelled and the replacement electrons is characteristic of the element atom in which the fluorescence process is occurring – thus, the energy of the emitted fluorescent X-ray is directly related to the specific element being analyzed. It is this key feature which makes XRF such a fast analytical tool for elemental composition.

It should be noted that in general the energy of the emitted x-ray for a particular element is independent of the chemistry of the material. For example, a calcium peak obtained from CaCO3, CaO and CaCl2 will be in exactly the same spectral position for all three materials.

  • Usage

    XRF spectroscopy is widely used for qualitative and quantitative elemental analysis of environmental, archaeological, geological, biological, industrial and other samples.
  • Compared to rival techniques, such as Atomic Absorption Spectroscopy (AAS), Inductively Coupled Plasma Spectroscopy (ICPS) and Neutron Activation Analysis (NAA), XRF has the advantage of being non-destructive, multi-elemental, fast and cost-effective.
  • Furthermore, XRF provides a good, uniform detection level across a large portion of the Periodic Table and is applicable to a wide range of concentrations, from 100% down to a few parts per million (ppm).
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Oxford Labs – FAQ

Which materials is XRF suitable for?
XRF can be used to test a wide range of materials from ceramics to metals and glass. It has various applications in industry, in environmental studies and the verification of antiquities. Read more

How do I get my item analyzed?
We can test on our premises or on site. Contact Oxford Labs for details of the services we offer.
How long does it take?
The process is fast and efficient. We aim to provide documentation and return of your items within two weeks. Read more

What results can I expect?
The chemical composition of the sampled area will be determined. We can offer an opinion as to the historical periods with which these results are consistent based on comparison with our database of known genuine results.
Does the process damage the item?
XRF does not damage the item. It is a safe and non-destructive process. Read more ...

What is the cost?
We offer a comprehensive service at a competitive price. Click here for our scale of charges.

What documentation will you provide?
The analysis will be fully documented and a signed certificate will be provided.