No abstract

No abstract

Among the possible variants of X-Ray Fluorescence (XRF), applications exploiting scanning Macro-XRF (MA-XRF) are lately widespread as they allow the visualization of the element distribution maintaining a non-destructive approach. The surface is scanned with a focused or collimated X-ray beam of millimeters or less: analyzing the emitted fluorescence radiation, also elements present below the surface contribute to the elemental distribution image obtained, due to the penetrative nature of X-rays. The importance of this method in the investigation of historical paintings is so obvious—as the elemental distribution obtained can reveal hidden sub-surface layers, including changes made by the artist, or restorations, without any damage to the object—that recently specific international conferences have been held. The present paper summarizes the advantages and limitations of using MA-XRF considering it as an imaging technique, in synergy with other hyperspectral methods, or combining it with spot investigations. The most recent applications in the cultural Heritage field are taken into account, demonstrating how obtained 2D-XRF maps can be of great help in the diagnostic applied on Cultural Heritage materials. Moreover, a pioneering analysis protocol based on the Spectral Angle Mapper (SAM) algorithm is presented, unifying the MA-XRF standard approach with punctual XRF, exploiting information from the mapped area as a database to extend the comprehension to data outside the scanned region, and working independently from the acquisition set-up. Experimental application on some reference pigment layers and a painting by Giotto are presented as validation of the proposed method.

The project FUXYA2020 was intended to design and prototype a low-cost basic energy dispersive X-ray fluorescence spectrometer for all those cases where there is not enough financial support to buy a commercial device. Indeed, home-made instruments are ideal when funds are low but constant over the years, as this approach allows the costs to be spread over a longer period of time. The FUXYA2020 was intended mostly for cultural heritage (CH) applications: we optimized the geometry to meet the requirements for both low Z matrix objects, such as glasses and ceramics, and medium-high Z materials, such as metals; besides, we designed a positioning system through Arduino components to obtain good results and repeatability for samples with a complex geometry. The FUXYA2020’s performance was tested both for qualitative and quantitative analyses, the former on pigment layers, and the latter on gold-based certified alloys, exploiting Axil-QXAS software for data elaboration. The classification of ancient ceramics based on multivariate analysis obtained through R environment was also carried out. The qualitative data on pigments have also been compared with the same data obtained by a commercial XRF spectrometer, demonstrating how our very simple and inexpensive prototype can be of great help for a rapid and reliable characterization of cultural heritage materials whenever commercial devices are unaffordable.

Angle Resolved XRF (AR-XRF) is an analytical technique in which the sample is analyzed at different angles of detection or irradiation. The change in the geometry affects the intensity of...