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FAQ - Frequently Asked Questions
Which chemical elements can be determined by scanning?
We have different generations of XRF scanners. Basically, the elements from potassium (K) to strontium (Sr) can be analysed (depending on the composition of the material).
The newer generation XRF scanners can also detect light elements starting with aluminium (Al) and heavy elements starting with rubidium (Rb) to barium (Ba) within a separate measurement run.
The newer generation XRF scanners can also detect light elements starting with aluminium (Al) and heavy elements starting with rubidium (Rb) to barium (Ba) within a separate measurement run.
What resolution can be measured and how long does a measurement take?
The smallest possible resolution is in the millimetre to micrometre range (min. 0.2mm on the "Superslit scanner"). However, with "normal" marine, i.e. bioturbated sediment, a resolution higher than 1cm (standard resolution) does not make much sense.
The measurement takes approx. 15-60 seconds per measuring point.
The measuring time depends strongly on the wavelength of the fluorescent radiation (different for different elements and depending on the position in the periodic table) and thus on the sediment composition.
At the beginning, up to three hours are required for the general introduction, the preparation of the core sections and the dead time test for the light elements.
At the end of all measurements, it should be ensured that all data is saved and the core sections are sorted back into the cold store or onto the shelf.
The following table lists approximate measurement times at different resolutions for measuring a 1 metre long core section.
The measurement takes approx. 15-60 seconds per measuring point.
The measuring time depends strongly on the wavelength of the fluorescent radiation (different for different elements and depending on the position in the periodic table) and thus on the sediment composition.
At the beginning, up to three hours are required for the general introduction, the preparation of the core sections and the dead time test for the light elements.
At the end of all measurements, it should be ensured that all data is saved and the core sections are sorted back into the cold store or onto the shelf.
The following table lists approximate measurement times at different resolutions for measuring a 1 metre long core section.
| Resolution | Minutes | Hours | Days |
| 2 mm | 278 | 4,63 | 0,58 |
| 5 mm | 74 | 1,23 | 0,15 |
| 1 cm | 37 | 0,62 | 0,08 |
| 2 cm | 19 | 0,31 | 0,04 |
Which cores can be scanned and what do they need to be like?
Cores with a diameter of 30-150 mm and a length of up to 1800 mm can be measured.
The half-shells should be completely filled with sediment. For optimum measurement results, the surface of the sediment should not be uneven.
The half-shells should be completely filled with sediment. For optimum measurement results, the surface of the sediment should not be uneven.
Is it possible to scan on the surface of U-channels?
In principle, yes:
When they are removed (the strips are pressed into the core), slight deformations can occur at the edges, depending on the density and elasticity of the sediment. In addition, U-channels tear, dry and shrink much faster than core halves.
So, if available or tangible, it is always better to scan intact core halves.
When they are removed (the strips are pressed into the core), slight deformations can occur at the edges, depending on the density and elasticity of the sediment. In addition, U-channels tear, dry and shrink much faster than core halves.
So, if available or tangible, it is always better to scan intact core halves.
Will I incur costs for using the XRF scanner?
Yes, a consumables fee. Details by email to Dr Ursula Röhl
What do I have to do if I plan to scan cores?
Write an email to Dr Ursula Röhl with the following information:
- Why would XRF scanner data be important for your scientific project?
- Which chemical elements should be used to answer which scientific questions?
- Which cores should be measured (project, core ID numbers)?
- How many core metres?
- In which resolution (step size) should be measured?
- How many and which energy runs? 10kV (lighter), 30kV (middle), 50kV (heavy elements)?
- 10 kV: (Mg-)Al through Fe
- 30 kV: Br through Zr
- 50 kV: Sr, Ba
- all depending on concentration and detection limits!
Information on accommodation and travelling:
For accomodation options see link above
Teerhof58 ( guest house in the city centre)
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