How Does Micro XRF Work?

Micro X-ray fluorescence, sometimes stylized as µXRF but more often referred to as micro XRF is a powerful analytical tool with a wide range of practical applications. It is an extremely versatile spectroscopic method ideal for elemental composition analysis and highly visual elemental surface mapping. But how does micro XRF actually work?

In this post, we will outline the working principles of Micro XRF and its benefits, as well as the differences between standard and micro XRF.

Analysing Paintings with Macro-XRF

What is Micro XRF?

Micro XRF is a colour map of the surface of a material providing elemental identification, it is a non-destructive form of spectroscopy that provides rapid screening of trace level elements for an array of sample types. With outstanding precision, high resolution, and fast scanning capabilities, micro XRF is a truly cost-effective analytical solution. The cost-benefits of high throughput are compounded by the fact that micro XRF spectrometers are compatible with many sample types with no preparation required. Micro XRF is subsequently highly versatile, with routine applications in archaeology, bioscience, forensics, geological studies, materials science and more.

How Does Micro XRF Work?

Conventional XRF spectroscopy uses high-energy X-rays to excite atoms in a bulk sample and induce fluorescence. Briefly: X-ray fluorescence occurs when electrons closely orbiting nuclei become excited and transition to a higher energy orbital, before relaxing back to their ground state. This relaxation requires a loss of energy, hence the emission of X-ray fluorescence. XRF spectroscopy, including micro XRF, acquires the unique spectral emissions—or fingerprint—of samples to determine their composition. Micro XRF depends on those same basic principles.

Described as an energy-dispersive form of X-ray spectroscopy, micro XRF uses polycapillary and doubly curved X-ray optics to create minute focal points on the surface of the sample. Focusing the X-ray beam into a micrometre-sized spot allows users to accurately map surface elements while simultaneously obtaining compositional information. These features make micro XRF the perfect method for small feature evaluation, measuring film and plating thickness, forensics and many other applications.

The actual working method varies depending on the type of micro XRF spectrometer used. Some are mobile and reconfigurable, meaning samples they can be brought into the field for in situ analysis of different samples. Simply aim the spectrometer at your sample for rapid, non-contact measurements. Benchtop devices typically have a sample chamber where samples must be placed, but the same limited sample prep benefits apply to non-portable devices.

Benefits of Micro XRF?
There are multiple benefits to micro XRF however, one of the main advantages is that it is a non-invasive, non-destructive method of analysing a wide range of samples.  Additional benefits of micro XRF are as follows:

  • No sample preparation required for any sample types (liquids, powders and liquids)
  • Sample material does not need to be cut, ground or dissolved
  • Fast measurements: 0.3ms per pixel
  • High spatial resolution: down to <20 µm X-ray spot size
  • Irregular shapes can be analysed easily
  • No sample damage
  • Versatile and can be used in a range of industries
  • Analyze elements as light as Oxygeb

These benefits are utilised in applications such as art, (paints and pigments,) geology,  biomaterials, metals, forensic science, paints and pigments, corrosive products, pathology, pharmaceuticals, archeology and many more industries where contamination may occur and materials need to undergo sample testing.

As the UK’s official distributor of Bruker Micro-XRF, Blue Scientific are able to assist with any questions you may have about micro XRF. Alternatively, if you are ready to make a purchase, don’t hesitate to contact us for a quote on:  +44 (0)1223 422 269 or