FISCHER FISCHERSCOPE X-RAY XDLM 231, Operator'S Manual

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48 FISCHERSCOPE ® X-RAY
User Interface of the WinFTM Software
A list of radiation components of one or more elements is displayed on the left next to the spec-
trum window.
3. Click in the elements list on one radiation component.
The energy lines associated with this element appear as colored lines in the spectrum window.
You can compare the peaks of the measured spectrum with the superimposed lines to identify
the elements that comprises the sample.
4. Repeat steps 2 to 3 to determine further elements of the sample.
You can change the colors of the spectra and the energy lines. To do so, select in the spectrum
window
View > Color… .
6.8.7 Energy
The energy distribution contained in the spectrum informs about the composition of the sample, be-
cause each occurring element of the sample reflects the qualitative composition through its peak
position (at the horizontal position specified for this element).
The higher the X-ray fluorescence energy of an element, the further to the right the corresponding
line will be in the spectrum.
According to Moseley’s Law, the energy increases as the atomic number of the respective element
increases, i.e., the lines of the “heavier” elements (those with a higher atomic number) are further
to the right in the spectrum.
The energy is measured in keV = kilo electron volts. 1 eV is the energy that an electron gains as it
moves through a field with a potential difference of 1 V.
6.8.8 Intensity
The intensity of a radiation is the amount of radiation that strikes a certain unit of area in a specified
time period.
In X-ray spectroscopy, the intensity of the radiation is measured as the count rate in counts per
second (cps).
Each peak in the spectrum corresponds to a relative maximum referenced to its surrounding. This
maximum correlates to the amount of radiating atoms of the corresponding element.
The higher the peak, the more atoms of the respective element are present in the sample, i.e., the
higher the concentration of the respective element in the sample.
Thus, the intensity of the spectral line is a measure for the quantitative composition of the sample.
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 deposited. The intensity of the spec-
tral 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 coat-
ings) and of the substrate material decreases, because their spectral lines are absorbed to a greater
degree, and thus weakened, by the thicker top coating.