Contribution of double interaction processes to x-ray fluorescence intensity

TIRAO, G.; G. STUTZ

X-RAY SPECTROMETRY

John Wiley & Sons, Ltd.

Lugar: INGLATERRA; Año: 2003 vol. 32 p. 13 - 24

0049-8246

An algorithm for calculating the contribution of double x-ray interaction processes to the primaryfluorescence emission is described. Four second-order processes including one scattering event (elastic or inelastic) and one photoelectric absorption were considered. Compton scattering events were more accurately described than in previous work by using a relativistic double-differential cross-section, which takes into account binding energy effects as well as momentum distribution of electrons of all atomic orbitals. Calculations of the contribution of double interaction processes were performed considering various experimental conditions (different sample thicknesses, atomic numbers, incident and outgoing angles and incident photon energies). The results show that for energies ranging from a few tens of keV up to 120 keV scattering contributions to the Ka1 fluorescence line vary from ¡­1% to several tens of percent(exceeding 50% for light elements). The relative scattering contribution is a rapidly increasing function of the sample thickness and reaches a saturation regime at a thickness of the order of the mean free path of the photons. The saturation value depends on the photon energy. Considerable deviations from a previous theoretical formalism were found. This discrepancy must be attributed to a more realistic description of single scattering events included in the present formalism. The present results are in very good agreement with those calculated from the transport theory.