## 3 Results and Discussion
For the S7 sector, the Raman spectrum (spectrum g) is characterized by the modes at 204 and 618 cm\({}^{-1}\) which are ascribed to Fe\({}_{2}\)O\({}_{3}\). The modes at 1375 and 1553 cm\({}^{-1}\) are given by the VDK pigment, and a broadband assigned to the humic components is found in the range 2900-3600 cm\({}^{-1}\). The Raman spectrum of the S8 sector shows evidence for the presence of VDK pigment, which is indicated by the broadband in which the modes at about 1342 and 1578 cm\({}^{-1}\) (spectrum h) can be observed. Additionally, the Raman spectrum of the S9 sector (spectrum i) confirms the presence of hematite (406 and 492 cm\({}^{-1}\) modes) and the VDK pigment (1337 and 1553 cm\({}^{-1}\) modes). The Raman band at 987 cm\({}^{-1}\) belongs to traces of barium sulfate, BaSO\({}_{4}\)[20] which could be intercalated inside the Armenian Bole. In the Raman spectrum of the S10 sector (spectrum l), the peaks at 1393 and 1578 cm\({}^{-1}\) are due to the VDK pigment. In Figure 3, the set of optical images acquired from the marked sectors is shown (S1, S2 S3, S4, S5, S6, S7, S8, S9, and S10) performed with the 20\(\times\) objective, where the investigated areas are marked by transparent red circles. In addition, the specimen N. 01.1622 has been investigated with supplementary Raman equipment based on an excitation source at 633 nm. In particular, due to the difficulty of sampling the art object, the analysis has been done on a fragment of small dimensions fragment (5 mm \(\times\) 2 mm) representative of the whole sample and denominated N. 01.1622_fragment and of which the photos are not shown. In this case, with the named sectors S11 and S12, we refer to two areas, with low different tonalities, of the samples N. 01.1622_fragment. In Figure 4 are shown the optical images performed with the 50\(\times\) objective acquired on N. 01.1622_fragment, on the sectors labeled S11 and S12. The investigated areas are marked by transparent red circles. The representative Raman spectra collected on the sectors labeled as S11 and S12 in focusing on the fingerprint region in the spectral range between 200\(-\)2000 cm\({}^{-1}\) and are shown in Figure 5.  
Figure 4: Collection of optical images from the investigated sectors S11 and S12 of the specimen N. 01.1622_fragment performed with the 50\(\times\) objective. The transparent red circles highlight the areas investigated. Figure 3: The collection of optical images from the investigated sectors S1–S10 (Figure 1) of the specimen N. 01.1622 performed with the 20\(\times\) objective. The transparent red circles highlight the areas investigated. The Raman spectrum collected on sector S11 (spectrum a) shows the presence of traces of iron oxides. Hematite (Fe\({}_{2}\)O\({}_{3}\)), with its Raman modes at about 295, 512, and 611 cm\({}^{-1}\) and \(\alpha\)-Goethite (\(\alpha\)-FeOOH) indicated by the mode at 695 cm\({}^{-1}\), have been found [15]. The presence of protein materials such as rabbit skin glue, which is used as a binding medium, has been confirmed. The rabbit skin glue can be identified by the Raman bands at 611, 798, 1034, 1163, 1242, 1448, and 1603 cm\({}^{-1}\). In particular, the mode located at 611 cm\({}^{-1}\) is referred to as the secondary amides (VI) and it describes the N-H deformation [21, 22]. The mode at 798 cm\({}^{-1}\) can be associated with the wagging vibration of the N-H bond [22]. The mode at 1034 cm\({}^{-1}\) is indicative of phenylalanine amino acid, while the mode at 1163 cm\({}^{-1}\) is indicative of phenylalanine amino acid. Figure 5: Representative Raman spectra collected on the sectors S11 (spectrum (**a**)) and S12 (spectrum (**b**)) of the specimen N. 01.1622_fragment and by using a laser source at 633 nm. is due to the anti-symmetric vibration of aliphatic CH\({}_{3}\) or the vibrational rocking of aromatic CH\({}_{2}\)[22; 23]. At 1242 cm\({}^{-1}\) is found the band related to amide III. The methylene scissoring is found at 1448 cm\({}^{-1}\)[23; 24].