Question

An X-ray fluorescence instrument must include a source of high-energy X-rays. Explain the role of these X-rays in thefluorescence process.

Answer 1

Fluorescence is a process in which a substance absorbs radiation of specific energy and re emits it back in the form of radiation of lower energy.

When any material is exposed to radiations of shorter wavelength like X-rays, it results in the ionisation of the atoms of the substance. X-rays are highly energetic that they ionise the atoms in such a way that the electrons from the inner orbits that are tightly held will be expelled. As a result the electrons from the higher orbits will fall into the spaces from where the electrons were removed (holes).

We know that when an electron moves from higher orbit to lower orbit it emits energy in the form of radiation. This process itself is called fluorescence as the material absorbed radiation of specific energy and emitted back radiation of lower energy.

Thus X-rays has its role in fluorescence.