## 3 Results and Discussion
### Identification of Pigments by Means of Raman Spectroscopy  
The analysis was carried out on 10 micro-fragments of pictorial film. They have been chosen in order to include all the possible colors present in a significant amount. From the microscope observation it was immediately clear that not all the pigments present in the paintings were represented. The samples are composed by many small brush strokes of different colors. Together with some classical pigments, such as ultramarine blue (Na\({}_{7}\)Ca(Al\({}_{6}\)Si\({}_{6}\)O\({}_{24}\))) found in the BB1 and BB6 samples and haematite (Fe\({}_{2}\)O\({}_{3}\)), the chromophore phase of red ochre in the BB1, BB2, BB5, and BB10 samples, many synthetic pigments or organic dyes were found in almost all samples (Tables 2 and 3). Few of them are inorganic compounds, such as cobalt-(II)-stananate (Co.nSnO\({}_{2}\)), known as cerulean blue (in BB11), and copper (II) arsenates (Cu\({}_{2}\)(AsO\({}_{4}\))(OH)\({}_{n}\)) (BB1 and BB3). The Raman spectra of organic pigments, especially in yellow, orange, and red colors, show characteristic features of the class of monoazo- and disazo-pigments but the comparison with the Raman spectra databases and the literature did not allow the complete and unambiguous identification of the dyes [34; 35; 36; 37; 38; 39; 40; 41; 42; 43; 44; 45; 46; 47; 48]. In only a few cases, the similarities of the spectra with those ofcontemporary pigments allowed some deductions to be made on their composition. It is very probable that many synthetic pigments used experimentally in the first post-war period were then abandoned or modified in the formulation, and therefore, no longer fully correspond to the current ones. In Figure 2, the Raman spectra of some compounds found on the painting samples, BB1 (blue), BB2 (orange), BB11 (blue), BB12 (yellow) are reported. \begin{table}
\begin{tabular}{c c c c} \hline
**Wavenumbers (cm\({}^{-1}\))** & **Assigned Species** & **Samples** & **Reference** \\ \hline
224, 245, 291, 411, 611, 660 & Haematite [Fe\({}_{2}\)O\({}_{3}\)] & BB1, BB2, BB5, BB10 & [37; 38; 39; 40] \\ \hline
207, 465 & Quartz [SiO\({}_{2}\)] & BB5 & [37; 38; 39; 40] \\ \hline
463, 988 & Baryte [BaSO\({}_{4}\)] & BB2, BB4, BB9, BB12 & [37; 38; 39; 40] \\ \hline
415, 1008 & Gypsum [CaSO\({}_{4}\)-2(H\({}_{2}\)O)] & BB2, BB4, BB5, B11 & [37; 38; 39; 40] \\ \hline
155, 281, 711, 1085 & Calcite [CaCO\({}_{3}\)] & BB5, BB6, BB9, BB10, BB11 & [37; 38; 39; 40] \\ \hline
1584 & Graphite & BB10 & [41] \\ \hline
1320, 1590 & Carbon & BB2, BB3, BB4, BB5, BB6, BB10 & [41] \\ \hline
258, 548, 1096 & Ultramarine blue [Na\({}_{7}\)Ca(Al\({}_{6}\)Si\({}_{6}\)O\({}_{24}\))] & BB1, BB6 & [42; 43] \\ \hline
868 & Copper (II) arsenate [Cu\({}_{2}\)(AsO\({}_{4}\))(OH)\({}_{n}\)] & BB1, BB3 & [44] \\ \hline
992, 1089, 1188, 1217, 1341, 1452, 1483 & Naphtol pigment (PR87) & BB9 & [35; 38; 45; 46; 47] \\  & [C\({}_{24}\)H\({}_{7}\)ClN\({}_{4}\)O\({}_{4}\)] & BB9 & [35; 38; 47; 45; 46; 47] \\ \hline
987, 1098, 1218, 1467, 1598, 1622 & Monoazo-pigment & BB6 & [35; 47; 45; 46; 47] \\ \hline
537, 673 & Cerulean blue [CoO.nSnO\({}_{2}\)] & B11 & [42; 46] \\ \hline
1285, 1433, 1083, 1570 & Naphtol pigment (PR1127) & BB12 & [35; 47; 48; 49; 47] \\  & [C\({}_{24}\)H\({}_{16}\)Cl\({}_{3}\)N\({}_{3}\)O\({}_{2}\)] & BB12 & [35; 47; 45; 46; 47] \\ \hline
1139, 1218, 1340, 1489, 1623 & Pigment Yellow 1 (PY1) & BB12 & [35; 47; 48; 49; 47] \\  & C\({}_{17}\)H\({}_{16}\)Na\({}_{4}\)O\({}_{4}\) & BB12 & [35; 47; 45; 46; 47] \\ \hline
790, 950, 1136, 1326, 1392, 1487, 1535, 1623, 1670 & Permanent Yellow 65 (PY65) & BB12 & [35; 47; 48; 49; 47] \\ \hline \end{tabular}
\end{table} 
Table 2: Main features observed in Raman spectra of wall painting fragments.