Global Raman imaging: a novel tool for compositional analysis.

Micro-Raman spectroscopy has been widely applied to the investigation of heterogeneous materials for it enables a not destructive way for the microscopic identification of the various chemical components. However it may not ever answer the question of how these species are distributed on a specific area. Global Raman imaging represents in this sense the ideal solution, for it combines Raman spectroscopy and digital imaging to provide molecular images that detail material morphology, composition and structure. By filtering a given Raman band over a wide sample area, the correspondent intensity distribution is immediately constructed in a bidimensional map which allows the user to easily and visually determine the location of even complex components in the irradiated sample area. An example of how a distribution map may be obtained by global Raman imaging is here reported for a fresco cross-sectioned sample