% of element A,B
intensity of element A,B
Cliff-Lorimer factor is NOT a constant but depends on the TEM voltage,
on the detector efficiency and several other parameters. Thus, accurate
results can only be obtained if a standard containing the elements
A and B in a well-defined ratio is used to determine kAB. Calculated
values of kAB, which are given by the various programs
used for X-ray spectroscopy, are only raw approximations and can
only be used for quick and rather inaccurate analyses. Although
the program output for the composition is a seemingly accurate value
with a rather small error bar, the actual error might be much higher
because of the kAB problem.
In all cases, the background ("bremsstrahlung") has to
be subtracted first. The accuracy of the quantification is additionally
by statistical errors of the measurement,
channeling, just to mention the most important effects.