In energy dispersive X-ray Fluorescence (EDXRF) the continuum "Bremsstrahlung" frequently appears to the right of the spectrum, in its most energetic range. How does this X-rays originated from the source interact with the sample to return to the detector? Could it be used this intensity as a sample density predictor?
Dear Ricardo Baettig ,
the continuum "Bremsstrahlung" in the high energy part of the EDXRF spectrum is the due to the Compton scatter of the Bremsstrahlung of the primary x-ray beam.
Its strength is proportional to (local) electron density of the sample; and thus for a given atomic number Z, proportional to the mass density of the sample.
Compton scatter imaging relies on this principle; here mainly the spectrum integral is used, but not the spectrum itself.
However there is some calibration necessary for getting absolute density numbers.
Best regards
G.M.
Dear Gerhard Martens ,
Thank you for your answer. I agree that the area under the curve for this range could be used as an approximation to Compton densitometry which is monoenergetic.
Best Regards,
Although most of the answers of Gerhard Martens are acceptable, the statement that the Compton scattering intensity is proportional to electron density, and thus related to atomic number Z need additional explanations. This is because Compton scattering intensity is usually believed to be stronger for light elements, but not for heavy elements.
Dear Jun Kawai ,
I totally agree, in this graph that I built with data from XCOM we can see the proportion of each interaction for the photonic energies used in XRF and for different Z. https://pastel.archives-ouvertes.fr/pastel-00001424
Best regards,
RBP
Thank you Ricardo Baettig for sharing the figure of Compton, photoelectric, and Thomson scattering portions. This figure is normalized with respect to the sum of these 3 cross-sections, but the absolute cross-sections of these three process will be more informative.
with best regards
Jun
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