Quantitative Analysis of Minium and Vermilion Mixtures Using Low-Frequency Vibrational Spectroscopy

Terahertz time-domain and low-frequency Raman spectroscopies are non-destructive techniques, making them ideal tools for analysis of historical pigments and delicate artifacts. Here, pure and mixed samples of the inorganic pigments, minium and vermilion, are investigated using a combination of terahertz time-domain spectroscopy, low-frequency Raman spectroscopy, and solid-state density functional theory. Data from pure and mixed samples enabled determination of the limits of detection and quantitation for both low-frequency techniques. These results emphasize the varying analytical capabilities of low-frequency vibrational spectroscopies in studying pigment mixtures.