X-ray fluorescence analysis (RFA)
Description
Application
X-ray fluorescence analysis is suitable for the examination of a wide range of different inorganic materials, especially metals, slags, ores, rocks, sediments, ceramics, glass, enamel, gems and pigments.
Currently, CEZA has four X-ray fluorescence spectrometers covering different fields of application:
- Micro-XRF with particularly large sample chamber (EAGLE III XXL): Non-destructive analysis of even relatively large objects (up to approx. 50 x 50 x 40 cm). By using capillary optics the diameter of the analysed area is only about 50 µm. This allows the analysis of even very small areas, for example exchanges in metal objects or different coloured areas in enamel.
- XRF sample processor for serial analysis (ARL Quant’X): Analysis of sample powders or metal chips, but also suitable for the non-destructive analysis of smaller objects (max. 25 x 25 x 5 cm) Precise measurement of the material composition, strong detection by using different excitations within one measurement (multiple excitation).
- Precious metal analyzer (Fischerscope XAN 150): Specially designed for the analysis of precious metals, but also suitable for other metals.
- Portable handheld analyzer (Niton XL3 Hybrid): Allows analysis of very large objects that do not fit into any laboratory instrument. Flexible use, analyses can also be performed off-site in museums, collections or in the field. Often used for metal and ceramic analyses.
To ensure the quality of our analyses, control analyses with standards of known and certified composition are carried out regularly. For serial analyses, control samples are measured with each measured series.
Basics
The basis of the method is the excitation of atoms with X-rays and the acquisition and evaluation of the secondary radiation emitted by the sample, which is also in the X-ray range. The secondary radiation is characteristic for each chemical element and allows both the qualitative and, by means of complex calculation methods and comparison with standard materials, the quantitative analysis of the material. No digestion is required for this method, the objects can be analysed in their original form. However, only the composition of the respective object surface is obtained in this way, since the depth of information of the analysis is only a few micrometers. Especially in the case of patinated metal objects, the composition of the corrosion layer can deviate considerably from the composition of the original metal. For this reason, it is recommended in such cases to remove chips from the inside of the sample by using a drill and then measure them by XRF. This procedure is particularly useful if a sample has to be taken anyway for further processing (e.g. authenticity test).
Limitations
The method is generally not suitable for organic materials because the light elements (especially H, C, N and O) cannot be determined.
Sample properties
Metal samples: 20-30 mg
Other sample material after consultation