## 3 Results
### Carbonate Pigments  
All five carbonate-based pigments (AZ-N, AZ-S, MA-N, MA-S and WL-S) presented characteristic bands assigned to carbonate groups (CO\({}_{3}^{2-}\)), though with slight differences in both ATR-FTIR and DRIFT modalities (Table 4). Similar to what occurred with the oxide-based pigments, bands related to copper ions (Cu\({}^{2+}\)) in AZ-N, AZ-S, MA-N, MA-S, or related to lead ions (Pb\({}^{2+}\)) in white lead (WL-S) were not identified as they are generally present below 600 cm\({}^{-1}\)[26]. Nevertheless, other characteristic IR bands, ascribable to each pigment, were observed. Figure 7: Absorbance spectra of synthetic chromium green (CG-S) obtained by ATR-FTIR (**a**) and DRIFT (**b**) modalities. See Table 1 for the explanation of the pigment identification codes. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Pigment**} & \multicolumn{2}{c}{**ATR-FTIR**} & \multicolumn{2}{c}{**DRIFT**} \\ \cline{2-5}  & **Wavenumber** & **(cm\({}^{-1}\))** & **Assignment 1** & **Wavenumber (cm\({}^{-1}\))** & **Assignment 1** \\ \hline \hline \multirow{7}{*}{AZ-N} & 3692, 3619 & \(\delta\)(–OH), kaolinite [42] & 3810, 3731 & –OH, kaolinite [35] \\ \cline{2-5}  & 3425 & \(\
u\)(–OH), azurite [52] & 3550, 3475 & \(\
u\)(–OH), azurite [14; 15] \\ \cline{2-5}  & 1498, 1412 & \(\
u_{\text{as}}\)(CO\({}_{3}\)\({}^{2-}\)), azurite [52] & 1914, 1677, 1545 & CO\({}_{3}\)\({}^{2-}\), carbonate [26], azurite (?) \\ \cline{2-5}  & 1465 & \(\
u\)(-O), azurite [69] & 1487, 1445 (_Reststrahlen_), 1421 & \(\
u_{\text{as}}\)(CO\({}_{3}\)\({}^{2-}\)), azurite [14; 15] \\ \cline{2-5}  & 1090, 1006 & \(\
u_{\text{s}}\)(CO\({}_{3}\)\({}^{2-}\)), azurite [52] & 1135, 1090 (_Reststrahlen_), 1007 & \(\
u_{\text{s}}\)(CO\({}_{3}\)\({}^{2-}\)), azurite [14] \\ \cline{2-5}  & 1030, 950 & \(\beta\)(–OH), azurite [52] & 1040, 935 & Al-OH, kaolinite [35] \\ \cline{2-5}  & 833, 813 & \(\delta\)(CO\({}_{3}\)\({}^{2-}\)), azurite [52] & 834 & \(\delta\)(CO\({}_{3}\)\({}^{2-}\)), azurite [10; 14; 15] \\ \cline{2-5}  & 765, 695 & \(\beta\)(CO\({}_{3}\)\({}^{2-}\)), azurite [52] & 783, 710 & \(\beta\)(CO\({}_{3}\)\({}^{2-}\)), azurite [14] \\ \hline \multirow{7}{*}{AZ-S} & 3957, 3850 & –OH [26] \\ \cline{2-5}  & 3425 & \(\
u\)(–OH), azurite [52] & 3750–2900 & \(\
u\)(–OH), azurite [14; 15] \\ \cline{2-5}  & 1508, 1396 & \(\
u_{\text{as}}\)(CO\({}_{3}\)\({}^{2-}\)), azurite [52] & 1913, 1885, 1685, 1620, 1530 & CO\({}_{3}\)\({}^{2-}\), carbonate [26], azurite (?) \\ \cline{2-5}  & 1469 & \(\
u\)(-O), azurite [69] & 1491, 1450 (_Reststrahlen_), 1407 & \(\
u_{\text{as}}\)(CO\({}_{3}\)\({}^{2-}\)), azurite [14; 15] \\ \cline{2-5}  & 1090 & \(\
u_{\text{s}}\)(CO\({}_{3}\)\({}^{2-}\)), azurite [52] & 1116, 1090 (_Reststrahlen_), 993 & \(\
u_{\text{s}}\)(CO\({}_{3}\)\({}^{2-}\)), azurite [14] \\ \cline{2-5}  & 950 & \(\beta\)(–OH), azurite [52] & 954 & \(\delta\)(-OH), azurite [15] \\ \cline{2-5}  & & & 870 & CO\({}_{3}\)\({}^{2-}\), calcite [35] \\ \cline{2-5}  & 818 & \(\delta\)(CO\({}_{3}\)\({}^{2-}\)), azurite [52] & & \\ \cline{2-5}  & 767, 739 & \(\beta\)(CO\({}_{3}\)\({}^{2-}\)), azurite [52] & 792, 765, 685 & \(\beta\)(CO\({}_{3}\)\({}^{2-}\)), azurite [14] \\ \hline \multirow{7}{*}{MA-N} & 3395, 3308 & \(\delta\)(–OH), malachite [18] & 3700–3000 & \(\
u\)(–OH), malachite [9] \\ \cline{2-5}  & & & 1970 & CO\({}_{3}\)\({}^{2-}\)[26], malachite (?) \\ \cline{2-5}  & & & 1852, 1605 & CO\({}_{3}\)\({}^{2-}\)[26], malachite (?) \\ \cline{2-5}  & 1490, 1379 & \(\
u_{\text{as}}\)(CO\({}_{3}\)\({}^{2-}\)), malachite [18; 52] & 1484, 1400 & \(\
u_{\text{as}}\)(CO\({}_{3}\)\({}^{2-}\)), malachite [9] \\ \cline{2-5}  & 1095 & \(\
u_{\text{s}}\)(CO\({}_{3}\)\({}^{2-}\)), malachite [52] & 1128, 1095, 1040, 935 & \(\
u_{\text{s}}\)(CO\({}_{3}\)\({}^{2-}\)), malachite [9] \\ \cline{2-5}  & 1042, 865 & \(\beta\)(-OH), malachite [52] & & \\ \cline{2-5}  & 815 & \(\delta\)(CO\({}_{3}\)\({}^{2-}\)), malachite [52] & 867 & CO\({}_{3}\)\({}^{2-}\)[35], malachite (?)