Infrared spectroscopic characterization of residues on archaeological pottery through different spectra acquisition modes

Amber Discs with Cross Decoration

“…It could be crystal water (few water molecules) or polymers, where OH groups cannot interact with each other. Vibrational bands characteristic of hydrocarbon chains at 2955, 2918, 2850 cm -1 in high frequency and 1473, 1463, 1377, 730 centimetres -1 in 'fingerprint' spectral regions (Font et al 2007;Shillito et al 2009;Lettieri 2015;Sathya, Velraj 2011;Venkatachalapathy 2003;Socrates 2001) were also found. Carboxyl groups are observed at 1740 and 1713 cm -1 (Font et al 2007;Shillito et al 2009;Lettieri 2015;Sathya, Velraj 2011;Venkatachalapathy 2003;Socrates 2001).…”

“…Vibrational bands at 1711 and 1664 cm -1 belong to carbonyl group, thus 1451 and 1413 cm -1 are scissoring vibration of CH 2 in chain (Socrates 2001). Also, vibrational band at 1413 can be assigned to carbonate stretching, and together with band at 872 cm -1 shows the presence of carbonates (Shillito et al 2009;Lettieri 2015). The broad band at 1052 cm -1 overlaps the vibrational modes of these functional groups C-O, O-Si-O, Al-O-Si (Font et al 2007;Shillito et al 2009;Lettieri 2015;Sathya, Velraj 2011;Venkatachalapathy 2003).…”

“…For a long time, IR spectral analysis was a common technique for the numerous investigations of natural resin, gum, pitch and tar, as well as amber artefacts in art and archaeological objects (Font et al 2007;Shillito et al 2009;Lettieri 2015;Sathya, Velraj 2011;Venkatachalapathy 2003). In recent years, the more modern method of Raman spectroscopy has appeared to be a powerful tool for investigating material at a molecular level, because it does not damage.…”

“…14, B) at 3340cm -1 is assigned to OH group, characteristic to hydrogen bonding in polysaccharides and other organic molecules capable to forming them. Bands at 2962, 2925 and 2850 cm -1 are specific for hydrocarbon chain (Font et al 2007;Shillito et al 2009;Lettieri 2015;Sathya, Velraj 2011;Venkatachalapathy 2003;Socrates 2001). Vibrational bands at 1711 and 1664 cm -1 belong to carbonyl group, thus 1451 and 1413 cm -1 are scissoring vibration of CH 2 in chain (Socrates 2001).…”

“…IR spectrum of light red material also shows bands characteristic to clays. Unlike the brown substance, there are two bands at 940, 914 cm -1 assigned to Al-OH deformation or Si-O bending vibrations (Font et al 2007;Shillito et al 2009;Lettieri 2015;Sathya, Velraj 2011;Venkatachalapathy 2003). Also, the new band is observed in the light red material IR spectrum at 1116 cm -1 which shows the presence of esters (ν(C-O-C)) (Vandenabeele et al 2000).…”