ATR and transmission analysis of pigments by means of far infrared spectroscopy

Abstract

In the field of FTIR spectroscopy, the far infrared (FIR) spectral region has been so far less investigated than the mid-infrared (MIR), even though it presents great advantages in the characterization of those inorganic compounds, which are inactive in the MIR, such as some art pigments, corrosion products, etc. Furthermore, FIR spectroscopy is complementary to Raman spectroscopy if the fluorescence effects caused by the latter analytical technique are considered. In this paper, ATR in the FIR region is proposed as an alternative method to transmission for the analyses of pigments. This methodology was selected in order to reduce the sample amount needed for analysis, which is a must when examining cultural heritage materials. A selection of pigments have been analyzed in both ATR and transmission mode, and the resulting spectra were compared with each other. To better perform this comparison, an evaluation of the possible effect induced by the thermal treatment needed for the preparation of the polyethylene pellets on the transmission spectra of the samples has been carried out. Therefore, pigments have been analyzed in ATR mode before and after heating them at the same temperature employed for the polyethylene pellet preparation. The results showed that while the heating treatment causes only small changes in the intensity of some bands, the ATR spectra were characterized by differences in both intensity and band shifts towards lower frequencies if compared with those recorded in transmission mode. All pigments' transmission and ATR spectra are presented and discussed, and the ATR method was validated on a real case study.

Fourier Transform Infrared Spectroscopy of Skin Cancer Cells and Tissues

“…Thus, biochemical analysis is restricted only to a few tens of microns (7,8); and this penetration is lower when the ATR probe is applied (7).…”

“…The rapid response coupled with the specificity of the biochemical information, obtained by vibrational spectroscopy (Raman and FTIR spectroscopy) indicate that these techniques are promising tools in the diagnosis in vivo (7)(8)(9).…”

Analysis of the Chemical Composition of Red Pigments and Inks for the Characterization and Differentiation of Contemporary Prints

“…The Kremer ''Cinnabar'' red pigment does not absorb infrared radiation in the range of 4000-350 cm À1 (Kendix et al 2009). The S and Hg detected by SEM-EDX are consistent with the lack of infrared signal and the presence of mercury and sulfur in the pigment.…”

Vibrational spectroscopy for the study of Chilean cultural heritage

“…The IR and Raman analyses confirm the presence of orpiment. In fact, the IR spectrum of the archaeological sample shows the characteristic orpiment bands between 250 and 400 cm −1 due to the νAs-S mode [33][34][35][36][37][38][39]. The Raman spectrum (Fig.…”