Testing gold leaves thickness calculations accuracy through Monte Carlo simulations and MA-XRF scanning

The use of X-Ray Fluorescence (XRF) scanning systems has become a common practice in many application sectors. In multi-stratified and inhomogeneous samples, the surface response is not reliable, so different spectral analysis techniques have been proposed to highlight the presence of surface stratification. One interesting (and commonly studied) case is that of gilding, i.e. the presence of a superimposing gold-leaf layer. The use of peaks ratio of a single element or of several elements in an XRF spectrum is a well-developed practice but still not used in the case of XRF scanning. This practice can yield information on the overlaying layer(s) thickness [1-4], if some properties of the sample are known – or at least estimated – beforehand: e.g. the overlapping layer chemical composition and the matrix effect contribution from the bulk material (thick ratio). This work presents a comparison between the gold leaves thicknesses values obtained from peaks ratio method combined with MA-XRF scanning and those obtained from Monte Carlo simulations of single spot analysis. The results from MA-XRF also creates a “3D-heightmap” of the superimposing layer (Figure 1) for a better statistical interpretation and visualization.