RoHS/WEEE HowDoes EDXRF

How does EDXRF work?

How does EDXRF work? Each of the atomic elements present in a sample produces a unique set of characteristic x-rays that is a fingerprint for that specific element. EDXRF analyzers determine the chemistry of a sample by measuring the spectrum of the characteristic x-rays emitted by the different elements in the sample when it is illuminated by high energy photons (x-rays or gamma rays).
A fluorescent x-ray is created when a photon of sufficient energy strikes an atom in the sample, dislodging an electron from one of the atom's inner orbital shells (lower quantum energy states). The atom regains stability, filling the vacancy left in the inner orbital shell with an electron from one of the atom's higher quantum energy orbital shells.
The electron drops to the lower energy state by releasing a fluorescent x-ray, and the energy of this fluorescent x-ray (typically meas85 ured in electron volts, eV) is equal to the specific difference in energy between two quantum states of the dropping electron.

Because the quantum states of each electron orbital shell in each different type of atom (each of the atomic elements) is different, the energies of the fluorescent x-rays produced by different elements are also different: When a sample is measured via XRF, each element present in the sample emits its own unique fluorescent x-ray energy spectrum.
By inducing and measuring a wide spectrum of the range of different characteristic fluorescent x-rays emitted by the different elements in the sample, XRF analyzers can rapidly determine the elements present in the sample and their relative concentrations, in other words, the elemental chemistry of the sample. For samples with known ranges of chemical composition, such as common grades of metal alloys.

It is important to note that, except in special circumstances, light elements cannot be measured directly with portable XRF analyzers, simply because x-rays with energies below 2 eV - including the characteristic x-rays of all elements lighter than sulpur (element 16) - are largely absorbed in air within a short distance. For this reason, light element XRF analysis is best performed in a vacuum chamber in a laboratory environment. In those tightly controlled lab conditions, XRF may be used to measure elements as light as beryllium and boron (elements 3 and 4) in highly uniform samples.