New frontiers in cultural heritage for polychrome wooden diagnostics: CT, MRI and micro-Raman imaging investigations.

To understand what has happened to a historic object, it is important to know the structure of the original wood. All this must be done through non-destructive techniques without compromising the integrity of the observed object. In recent years, it emerged the importance of defining the relationship between the morphological characteristics and the micro- and ultrastructure of wood tissues, as expressed by the thickness of tracheid walls, lignin content and crystallinity of cellulose as well as by its hydrophobic capacity. On the overall, it is essential a profound knowledge of the compositional-structural and morphological properties of wood and, particularly, a knowledge of their interdependencies. With this information, it will be possible to understand the degradation that has occurred over time and, in turn, to define a potential method of conservation and preservation of the artworks. Technological progress has allowed the development of many non-destructive diagnostic methods, such as X-rays Computed Tomography (CT), ultrasounds (Zisi 2017), Nuclear Magnetic Resonance (NMR) (Proietti 2014) technique together new working configurations of the conventional FTIR and Raman spectroscopies (Macchioni 2012, Gierlinger 2007). CT and NMR techniques are very widespread in the field of medicine, allowing to observe internal parts of the human body without any harm to the patient. Although they are non-destructive diagnostic tool traditionally applied in clinical medicine, its application to materials science is a field in continuous evolution. The research activities carried out during the PhD course in Physics whose results are reported in this thesis regard the development of a protocol suitable for the study of ancient wood by clinical CT and NMR. First, contemporary wood samples were analysed to define and optimize CT and NMR procedures. Then, the same techniques were used to characterize archaeological waterlogged wood samples and ancient wooden objects. Then, CT and NMR results were combined to those obtained by micro-imaging NMR, micro-Raman and FTIR spectroscopies. The synergic use of these techniques, probing the system energies on different scales, is proposed as an innovative approach, which have allowed to carry out wood and wooden works analyses in a systematic and complete manner. Furthermore, for the first time, the interesting potentiality of the comparative analysis of all the collected data have allowed to characterize materials on an Egyptian Coffin and its implementation methods, making possible to recognize reuse wood planks. On waterlogged wood samples coming from Naples and Denmark information about water imbibition were collected. Identification of the species was performed for the first time with NMR-microimaging analysis. CT analyses were carried out at Neuroradiology Unit-Department of Policlinico University Hospital of Messina, Italy. NMR measurements were carried out in the NMR Laboratory of Institute of Complex System of the National Italian Council of Research (CNR-ISC) at Sapienza University of Rome and at IRCCS Santa Lucia of Rome, Italy. Ultimately, FTIR and Raman analyses were carried out in MNS laboratories in the MIFT Department of the University of Messina.