Since the identification of dyes in archaeological remains has been a long-standing challenge, the project reported in this article used two non-destructive analytical techniques, Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS) and Surface-Enhanced Raman Spectroscopy (SERS), for dye detection, and the analysis of results were compared.
Major problems in the identification of dyes in archaeological remains include contamination by environmental conditions over long periods of time, small amounts and limited availability of excavated samples, and low concentrations of dyestuff in the obtained samples. To address these issues, highly sensitive and non-destructive techniques are required. TOF-SIMS provides high detection efficiency for the analysis of organic materials, and SERS is a useful technique for the detection of dyes in ancient textiles. An Ag colloid was employed to overcome the limitations of normal Raman measurement, such as background fluorescence and weak Raman signals in small amounts of components. To identify the dyes used in ancient textiles, standard samples prepared using various dyestuffs and historical samples were analyzed with TOF-SIMS and Raman techniques. From the TOF-SIMS and the SERS spectra, dyestuffs such as alizarin, berberine, and indigo were identified in ancient textiles. The results suggest that TOF-SIMS and SERS are efficient non-destructive techniques for the characterization of archaeological textiles. (publisher abstract modified)