Raman Spectroscopy: New Light on Ancient Artefacts

Abstract

Raman spectroscopy, being a laser spectroscopic method, is gaining increasingly more interest for applications in the field of art and archaeology. The technique is especially appreciated for its nondestructive character, the speed of analysis, and the ability to obtain molecular information on a whole range of materials, organic as well as inorganic. Although the Raman effect was observed for the first time in 1928, it was not until the end of the 1980s when instrumental improvements enabled the analysis of microsamples, thus allowing the application of this method in archaeometry. Next to the identification of inorganic materials, organic matter such as resins and binders has often been examined by using Raman spectroscopy. Together with the comparison to reference spectra, spectral interpretation is often involved to attribute the Raman bands to specific molecular vibrations. This is mainly of importance when studying archaeological materials that have suffered degradation over time. Recently, fiber optics instrumentation became available for the direct and nondestructive analysis of artifacts. Although the approach seems simple and easy to apply, several drawbacks need attention. For instance, due to the different nature of a Medieval manuscript, Medieval wall paintings on the vault of a chapel, panel paintings, and polychrome sculptures, different experimental setups are needed to deal with the diversity of artifacts. Moreover, these setups need to guarantee sufficient stability to allow focusing of the laser beam on the artifact.