Info

The depth from which the major proportion of the XRF signal comes from depends on the attenuation of both, the excitation and the fluorescence radiation. This information depth is therefore influenced by sample/matrix parameters, by the fluorescence energy of the corresponding x-ray line and by the excitation conditions. It is not identical to the attenuation length of the fluorescence line in the given matrix, since the attenuation of the exciting radiation has to be considered as well.

This online calculator computes the information depth for K-alpha and L-alpha lines of all elements from Carbon or Calcium, respectively to Uranium in a given matrix (main composition of the sample) and for a given spectrometer configuration. You can specify absorbers in the excitation channel like the air path or primary filters. Furthermore, you can specify the amount of fluorescence that has to come from the information depth.

How does it work? For each data point in the graph below, the corresponding element is added as trace element to the matrix that you have defined. Then the fluorescence of the regarded line is calculated for a bulk sample and finally the thickness of this virtual sample a varied as long, as the fluorescence is decreased to the amount you have specified for the definition of the information depth.