Hp. Urbach et Pk. Debokx, CALCULATION OF INTENSITIES IN GRAZING-EMISSION X-RAY-FLUORESCENCE, Physical review. B, Condensed matter, 53(7), 1996, pp. 3752-3763
The sensitivity of x-ray fluorescence spectroscopy to surface and subs
urface layers in the nanometer regime can be greatly enhanced by measu
ring the fluorescence radiation that is emitted at grazing angles. In
this paper, we present a formalism for the calculation of x-ray fluore
scence intensities that is also valid under grazing emission condition
s. By applying asymptotics to plane-wave expansions, an approximate so
lution to Maxwell's equations for a radiating point source in a layere
d system is derived, without the use of the optical reciprocity theore
m. In the computation of the fluorescence intensity, secondary and hig
her-order fluorescence effects are taken into account. The total fluor
escence of a particular layer is obtained by integrating the contribut
ions of point sources at different depths. The derived expressions com
pare well with the measured angular dependence of the fluorescence int
ensity in a number of typical examples.