Modular MA-XRF Scanner Development in the Multi-Analytical Characterisation of a 17th Century Azulejo from Portugal

Abstract

A modular X-ray scanning system was developed, to fill in the gap between portable instruments (with a limited analytical area) and mobile instruments (with large analytical areas, and sometimes bulky and difficult to transport). The scanner has been compared to a commercial tabletop instrument, by analysing a Portuguese tile (azulejo) from the 17th century. Complementary techniques were used to achieve a throughout characterisation of the sample in a complete non-destructive approach. The complexity of the acquired X-ray fluorescence (XRF) spectra, due to inherent sample stratigraphy, has been resolved using Monte Carlo simulations, and Raman spectroscopy, as the most suitable technique to complement the analysis of azulejos colours, yielding satisfactory results. The colouring agents were identified as cobalt blue and a Zn-modified Naples-yellow. The stratigraphy of the area under study was partially modelled with Monte Carlo simulations. The scanners performance has been compared by evaluating the images outputs and the global spectrum.

Position-Sensitive Bulk and Surface Element Analysis of Decorated Porcelain Artifacts

“…In this case, as the surfaces of the decorated objects are not homogeneous, the information was carried by the spatial variation of the X-ray spectrum. Therefore, a handheld XRF device must be put close to the surface, held firmly, and positioned based on a video-feedback by the operator, or can be coupled to a computer-controlled, motorized xyz sample stage to precisely position the object relative to the sampling spot or make raster scanning element mapping [ 24 , 46 , 47 ] ( Figure 1 c). Although the X-ray spot size of such handheld XRF devices (3–8 mm) is larger than dedicated micro-XRF scanners [ 48 ], this class of equipment is still a viable, affordable, and portable solution for many heritage-science problems, especially if combined with sophisticated image post-processing [ 49 ].…”

The colours of Portuguese azulejos: a review

“…Num estudo que incluiu azulejos portugueses de várias cronologias e proveniências [7], os autores concluíram que o azul de cobalto na azulejaria portuguesa é maioritariamente caracterizado pela associação elementar Fe-Co-Ni-As. Este resultado é corroborado pela restante literatura, embora esta se trate de publicações apenas focadas no século XVII [2,[8][9][10][11][12][13][14].…”

Atomic spectrometry update: review of advances in X-ray fluorescence spectrometry and its special applications

“…The performance of a modular macroXRF spectrometry scanner developed in-house by Lins et al 94 was compared to that of a commercial instrument by analysing a Portuguese tile (azulejo) from the 17th century. Multiple X-ray detectors (3 SDDs), used to achieve shorter dwell times, were configured identically so that acquisition could be synchronised and the sum spectrum from all detectors viewed in live time.…”