A note on the characterization of bismuth black by Raman microspectroscopy

Inspired by the discovery of bismuth metal used as a pigment in a fifteenth century illuminated manuscript, the identification of bismuth compounds by Raman spectroscopy is investigated. Raman spectra of bismuth metal powder, bismuth (III) sulfide (Bi2S3) and bismuth (III) oxide (alpha-Bi2O3) are presented. The influence of excitation laser wavelength is explored, along with the laser-induced oxidation of bismuth to alpha-Bi2O3 and beta-Bi2O3. The implication of these results with respect to the selection of appropriate analytical protocols in the investigation of bismuth pigments in works of art is discussed. Copyright (c) 2009 John Wiley & Sons, Ltd.