FISCHER FISCHERSCOPE X-RAY 4000 Series, Operator'S Manual

Page: 43 / 170

FISCHERSCOPE
®
X-RAY 43
The Spectrum Window User Interface of the WinFTM Software
Intensity: Dependency on the Coating Thickness
With coated samples, one generally sees the spectra of all coatings involved, their
elements as well as the spectrum of the substrate material where the coatings are depos-
ited. The intensity of the spectral lines of the coating material increases with an increase
in the coating thickness, because the number of the atoms in the coating increases, and
thus the intensity of the radiation of all atoms. At the same time, the radiation of the atoms
of coatings located under the top coating (buried coatings) and of the substrate material
decreases, because their spectral lines are absorbed to a greater degree, and thus weak-
ened, by the thicker top coating.
Intensity: Dependency on the Measurement Distance
The total intensity of the X-ray fluorescence radiation emitted by the specimen decreases
with the distance D of the detector from the sample with
1/D
2
, because the solid angle of
radiation collected by the detector decreases with an increase in the distance as well,
while the area of the radiation entry window of the detector remains the same.
For the coating thickness of a sample to be computed correctly, the distance D is auto-
matically taken into account by the evaluation software.