XRF is physically based on the excitation of atoms with X-rays and the detection of secondary characteristic X-rays emitted by the sample. This analysis technique is non-destructive and requires no chemical digestion. Metal objects, glassware, enamels, gemstones and other inorganic materials can be analyzed non-invasively without taking samples.
However, non-invasive analysis detects only the composition of the object’s surface. Due to alteration and corrosion of metal objects, for example, the composition of the surface layer differs often from the original unaltered metal. For this reason it is always better to take samples from the inner metal core with a small drill and analyze the drillings with XRF. When a sample has to be taken for further investigations (e.g. authenticity test), this procedure makes sense in particular. The sample material will not be altered or destroyed by the X-rays.
Main fields of application of the XRF at the Curt-Engelhorn-Centre are:
- Metals (copper based alloys, silver and gold), non-destructively but also sample material.
- Pottery and ceramic
- Glass and enamel
- Geologic materials (ore, clay, soil, rock)
For different applications three XRF spectrometers are currently in use at the Curt-Engelhorn-Center:
- µ-XRF with an extra large sample chamber (EAGLE III XXL): non-destructive analysis of archaeological objects and works of art (max. size approximately 50 x 50 x 40 cm). The spectrometer is equipped with a capillary optics that focuses the primary X-ray beam to a size of about 50 µm. This allows the analysis of very small areas and structures like damascenes in metal objects or different colored areas in enamels.
- XRF equipped with an automatic sample changer for high sample throughput (ARL Quant’X). The sample tray is removable and so the instrument can also be used for non-destructive analysis of smaller objects (max. size 25 x 25 x 5 cm). Compositional analysis is precise and highly sensitive due to multiple excitation conditions with automated operation.
- Fischerscope XAN 150 for high-precision analysis of noble metals and copper alloys.