Quantification of thin intermediate layers by confocal µXRF

PEREZ, R.D; SÁNCHEZ H.J.; PEREZ, C.A.; RUBIO, M.

Cabo Frio (Brasil)

Congreso; XI Seminario Latinoamericano de Análisis por Técnicas de Rayos X - SARX 2008; 2008

Universidad Federal do Rio de Janeiro

Recently, the capabilities of the micro-x-ray fluorescence spectroscopy (m-XRF) were expanded by the confocal setup. It consists of x-ray lenses in the excitation as well as in the detection channel. For intermediate thin homogeneous layers a scanning in the normal direction to the surface provides information of its thickness and elemental composition. For multilayers samples it also provides the order of each layer in the stratified structure. In the present work we propose a new quantification algorithm to apply in the surface analysis by confocal m-XRF.  It is an iterative procedure valid to thin intermediate layers where the exponential attenuation of the x-ray fluorescent radiation cannot be approximated. The algorithm is a consequence of the application of the convolution theorem to the theoretical expression of the x-ray fluorescence emission produced in confocal m-XRF. The analytical expressions involved in the present quantification algorithm are the same as those used for quantification of intermediate thin layers by conventional XRF. In this way, some of the analytical processes applied in conventional XRF can be adapted to confocal m-XRF. The new algorithm was applied to analyse by confocal m-XRF a sample of paint layers on a glass substrate. To test the precision of the proposed algorithm, the present results were compared with conventional XRF analysis.