FT-Raman; Raman microscopy; Raman spectroscopy
Raman spectroscopy is a technique used to identify and characterize organic and inorganic compounds, and it has been used in the examination of materials possessing archaeological significance (Smith and Clark, 2004; Vandenabeele et al., 2007). It relies on inelastic scattering (i.e., Raman scattering) of monochromatic electromagnetic radiation, typically a laser, interacting with molecular vibrations in a sample. Specifically, photons of incident light strike the surface of a target specimen, and most of the photons are absorbed, reflected, or transmitted by the target material. A small part of the photon beam interacts with the specimen by deforming the atomic charge and inducing an instantaneous dipole moment in the molecule under investigation. Molecules affected in this way are excited to a higher energy state that is unstable and decays immediately; the decay process occurs mostly by elastic scattering (known as...