X-Ray Fluorescence Analytical Techniques - CNSTN : Centre ...

Figure II.10: Background contribution in an EDX spectrometer with monochromatic
17.5 keV excitation.
V. The Approach to Quantification in EDXRF Analysis
The approach to quantification in EDXRF analysis is usually different for thin,
intermediate thickness and infinitely thick samples.
V.1 Thin Samples Technique
If a homogeneous sample to be analysed has a very small mass per unit area (or
thickness), the detected intensity of characteristic X-rays, Ithin, of the ith element is simply
given by:
with
and
Ithin = Sm i i , (II.3)
⎛ 1 ⎞
G
⎜ ⎟
Si = Io( Eo) ε( Ei) τi( Eo) ωipi 1
sin φ ⎜ ⎟
⎜ j ⎟
⎝ i ⎠
, (II.4)
mi =µ i m.
(II.5)
Where G is the geometry factor; φ is the effective incidence angle for primary radiation; Io(Eo)
is the intensity of primary photons of energy Eo (monochromatic excitation), ε(Ei) is the
detector efficiency for recording the photons of energy Ei; τi(Eo) is the photoelectric mass
absorption coefficient for the ith element at the energy o, in cm 2 .g -1 ; ji is the jump ratio; mi
and µi are the mass per unit area and the weight fraction of the ith element, respectively; and
m is the total mass per unit area of a given sample.