![]() To date, one of the most significant results achieved has been the extension of conventional UV photography to more advanced spectroscopy and imaging methods to examine luminescence from surfaces. The group has been established with the aim of developing novel optical methods for studying in non-invasive way materials of cultural interest. The research described in this thesis has been carried out at the Imaging and Spectroscopy for Cultural Heritage Laboratory of the Physics Department of Politecnico di Milano. The painting under study was furthermore compared with artworks of renowned forgers in an attempt to identify the forger in disguise. ![]() The painting was created at the earliest in the 1930s possibly as a consequence of the rediscovery of Ruyscher, and the deliberate use of an aged panel supports an intent to deceive and hence classifies the object as a forgery. ![]() The applied methodology sheds new light on the story of the object itself. Radiocarbon analyses of the wooden panel indicated that the tree was probably cut down in the mid-eighteenth century, whereas spectroscopic analyses pinpointed the twentieth century as a timeframe for the application of the pictorial layers. In this research paper, the combination of multiple analytical techniques ranging from radiocarbon dating of the support material to multispectral imaging and spectroscopic analyses (XRF, SEM-EDS, FTIR and Raman) of the pictorial layer offers a comprehensive analysis of the object. Despite a prestigious career, Ruyscher, who possibly was a pupil of Rembrandt and Hercules Seghers, vanished from art history after his death and was only rediscovered in the 1930s. ![]() In 2014, a painting attributed to the seventeenth century Dutch artist Jan Ruyscher appeared on the art market. In the selected samples, the method allows the identification of modern inorganic pigments such as cadmium-based pigments, zinc white, titanium white, chrome yellow, ultramarine and cinnabar. The effectiveness and limits of the proposed combined method is discussed through analysis of a corpus of stratigraphic micro-samples from Russian Avant-garde modern paintings. The spatial heterogeneities, detected in the micro-sample, are investigated with Raman spectroscopy (785-nm in CW mode) for a further identification of the paint composition on basis of the molecular vibrations associated with the crystal structure. In this work, the technique is beneficially applied for identifying different luminescent semiconductor and mineral pigments, on the basis of their spectral and decay kinetic emission properties. The TRPL device is based on pulsed laser excitation (excitation wavelength = 355 nm, 1 ns pulse width) and time-gated detection, and it is suitable for the detection of photolu-minescent emissions with lifetime from few nanoseconds to hundreds of microseconds. In this context, we propose a combined-microscopy approach based on the application of time-resolved photoluminescence (TRPL) micro-imaging and micro-Raman spectroscopy. For these purposes, the study of stratigraphic micro-samples provides unique information on the complex heterogeneity of the pictorial artworks. In conservation science, the identification of painting materials is fundamental for the study of artists' palettes, for dating and for understanding ongoing degradation phenomena.
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