Calibration standards for µXRF

Calibration standards for µXRF
Micro-X-ray fluorescence spectroscopy

In micro X-ray fluorescence analysis, a sample is excited by X-rays. Depending on the energy of the X-rays and the material properties, the penetration depth of the X-rays and thus the excited volume may differ

Excitation means that electrons close to the atomic nucleus are knocked out from the inner shells of the atom. This results in a transition of electrons of higher energy levels to the energetically lower state. During this transition, energy is released as a photon. This fluorescence radiation is element specific. Measurements of this radiation therefore give information about the elements in a sample. In a spectrum, the energy or frequency is plotted against the intensity, i.e. the number of photons counted.

In order to not only evaluate this signal qualitatively, but also to deduce the concentration of the element in the sample from the intensity, suitable reference materials are required.

Fig. 1 Element map of iron in four different nano-pellets compared to their unprocessed predecessors. The top row shows four original powders and the rows below three of their processed counterparts. Light colors indicate a particularly high concentration of iron. It is clearly shown that there are no spikes in iron concentrations, showing the improved homogeneity of the nano-pellets. Photo, courtesy of Dr. Roald Tagle, Bruker Nano GmbH Berlin.

In contrast to conventional XRF, the measuring spot has a diameter in the micrometer range (approx. 15 µm). This is achieved by focusing the X-ray beam through various, mostly polycapillaric optics. The small size of the measuring spot places high demands on the homogeneity of the reference material. Our pellets, which are made of nano-particulate powder, meet this requirement and are also sufficiently stable to be used in systems with vacuum technology. Due to its spatial resolution in the micrometer range, the µRFA is particularly suitable for spatially resolved analysis in geological samples, providing information about the course of geological processes and information for the exploration of mineral resources. Order a fitting sample holder with your samples.