EN Physics: Laboratory Experiments

Page 289

13 X-ray Physics 13.6 X-ray fluorescence spectroscopy

X-ray fluorescence spectroscopy / layer thickness determination

P2545201

Fe-fluorescence lines as a function of the number n of the pieces of aluminium foils placed on the substrate

Principle X-ray fluorescence analysis (XRF) is suitable for the non-contact and non-destructive thickness measurement of thin layers as well as for determining their chemical composition. For this type of measurement, the X-ray source and detector are located on the same side of the sample. When the layer on the substrate is subjected to X-rays, the radiation will penetrate the layer, if it is sufficiently thin, to a certain extent, depending on the thickness, and in turn cause characteristic fluorescence radiation in the material of the underlying substrate. On its way to the detector, this fluorescence radiation will be attenuated by absorption at the layer. The thickness of the layer can be determined based on the intensity attenuation of the fluorescence radiation of the substrate material. Tasks 1. Calibrate the semiconductor energy detector. 2. Measure fluorescence spectrum of the iron substrate with different numbers n of pieces of aluminium foil with the same thickness placed on the substrate (including n = 0). Determine the intensity of the Fe-Kalpha fluorescence line. 3. Plot the intensity of the Fe-Kalpha fluorescence line as a function of the number of pieces of aluminium foil placed on the substrate in linear and semilogarithmic way. 4. Determine the intensity of the Fe-Kalpha fluorescence line for various numbers of pieces of aluminium foil that are fastened in front of the outlet of the tube of the energy detector. 5. Calculate the thickness of the aluminium foil. 6. Execute tasks 2 to 4 for copper foil on molybdenum or zinc substrate.

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law of absorption mass attenuation coefficient saturation thickness matrix effects semiconductor energy detectors multi-channel analysers

Main articles XR 4.0 expert unit XR 4.0 X-ray energy detector (XRED) XR 4.0 X-ray goniometer XR 4.0 X-ray plug-in unit W tube Multi channel analyser XR 4.0 X-ray Specimen set metals for X-ray fluorescence, set of 7 XR 4.0 X-ray Specimen set metals for fluorescence, set of 4 measure Software multi channel analyser XR 4.0 XRED cable 50 cm XR 4.0 X-ray Univ. crystal holder f.x-ray-unit

09057-99 09058-30 09057-10 09057-80 13727-99

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09058-31

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09058-34 14452-61 09058-32 09058-02

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What you can learn about ▪ ▪ ▪ ▪ ▪

Bremsstrahlung characteristic X-radiation fluorescent yield Auger effect coherent and incoherent photon scattering

PHYWE Systeme GmbH & Co. KG · www.phywe.com 287


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