Advances in Raman mapping of works of art

Raman mapping can provide molecular information to complement data derived from other analytical techniques in works of art and other objects of cultural significance. Raman mapping can be performed using a motorized microscope stage that moves a sample or an object point by point in two spatial directions. The method can be used both noninvasively in works of art that fit under a microscope objective and in microsamples when, for example, obtaining information on the samples' layering structure is necessary. This paper reports on the development of a Raman mapping approach based on a set of scanning mirrors that direct the laser beam in two spatial directions, vertically through the microscope head or through a horizontal exit on the Raman microspectrometer. The first configuration still has limitations in terms of the size of the work of art that can be analyzed, as it has to fit under the microscope objective, but considerably larger objects can be studied when using the scanning mirrors placed in the horizontal exit. In this paper, the advantages and limitations of these two Raman mapping approaches are compared and discussed on the basis of an example of a contemporary oil painting on canvas. Copyright (C) 2010 John Wiley & Sons, Ltd.