Theoretical model for the calculation of interference effects in TXRF and GEXRF

PÉREZ, ROBERTO DANIEL; SÁNCHEZ, HÉCTOR JORGE; RUBIO, MARCELO

X-RAY SPECTROMETRY

JOHN WILEY & SONS LTD

Año: 2001 vol. 30 p. 292 - 295

0049-8246

Interference effects between the contributions of transmitted and reflected radiation are observed during x-ray propagation at grazing angles in stratified media. This phenomenon affects the fluorescence intensity in grazing incidence experiments [total reflection x-ray fluorescence (TXRF)] and grazing emission experiments [grazing emission x-ray fluorescence (GEXRF)], thus producing a characteristic interference pattern in the fluorescence spectra. The theoretical description of this effect can be studied by using models based on the general problem of an electromagnetic wave propagating through a stratified medium. In this work, a new approach to this problem is presented based on the development of approximations in the electric field. This approach uses a new theoretical formalism introduced recently. By using this new model, we proved that in order to evaluate the interference effects of an electric field in any surface layer, the influence of the surface layers over the layer analyzed can be neglected. By using this result, the precision obtained in the calculations of an electric field is acceptable. As an example, we present theoretical calculations for x-ray propagation at glancing angles in testing stratified structures. The usual theoretical models for data analysis of TXRF and GEXRF experiments can be simplified by applying the present model. Furtheremore, our results allow a better understanding of the experimental data obtained with both techniques. Copyright © 2001 John Wiley & Sons, Ltd.