Analysis of pigments in polychromes by use of laser induced breakdown spectroscopy and Raman microscopy  M. Castillejo a, * , M. Martı ´n a , D. Silva a , T. Stratoudaki b , D. Anglos b , L. Burgio c , R.J.H. Clark c a Instituto de Quı ´mica Fı ´sica Rocasolano, CSIC, Serrano 119, 28006 Madrid, Spain b Foundation for Research and Technology-Hellas (FO.R.T.H.), Institute of Electronic Structure and Laser, Laser and Applications Division, P.O. Box 1527, 71110 Heraklion, Greece c Christopher Ingold Laboratories, University College London, 20 Gordon St., London WC1H 0AJ, UK Received 8 August 1999; accepted 11 November 1999 Abstract Two laser-based analytical techniques, Laser Induced Breakdown Spectroscopy (LIBS) and Raman microscopy, have been used for the identification of pigments on a polychrome from the Rococo period. Detailed spectral data are presented from analyses performed on a fragment of a gilded altarpiece from the church of Escatro ´n, Zaragoza, Spain. LIBS measurements yielded elemental analytical data which suggest the presence of certain pigments and, in addition, provide information on the stratigraphy of the paint layers. Identification of most pigments and of the materials used in the preparation layer was performed by Raman microscopy.  2000 Elsevier Science B.V. All rights reserved. Keywords: Laser induced breakdown spectroscopy; Raman microscopy; Polychromes on wood; Pigments; Spanish cultural heritage 1. Introduction Polychromes on wood are amongst the most impor- tant artistic expressions of southern Europe from the XV century onwards. In polychromes, the wood substrate is usually covered with a white preparation (primer) on top of which successive paint layers of pigments and binding media mixtures are applied [1]. The restoration of this type of artwork channels much of the effort addressed to the conservation of Spanish cultural heritage. A detailed characterisation of the materials and pigments that are present in successive layers of a polychrome is a necessary task to be accomplished before any restoration work can be attempted. Analysis of the materials present in the artwork (pigments and dyes, binding media, etc.) include a variety of complementary techniques based upon optical and electron microscopy, infrared, visible and ultraviolet spectroscopy, X-ray diffraction, X- ray fluorescence or gas/liquid chromatography coupled to spectroscopic or mass spectrometric detec- tion schemes, etc. [1]. This work demonstrates the combined application of two laser-based analytical techniques, laser induced breakdown spectroscopy (LIBS) and Raman microscopy, for the identification of pigments on painted artworks. LIBS measurements yielded Journal of Molecular Structure 550–551 (2000) 191–198 0022-2860/00/$ - see front matter  2000 Elsevier Science B.V. All rights reserved. PII: S0022-2860(00)00386-0 www.elsevier.nl/locate/molstruc  Dedicated to Professor James R. Durig on the occasion of his 65th birthday. * Corresponding author. Tel.: + 34-91-561-9400; fax: + 34-91- 564-2431. E-mail address: marta.castillejo@iqfr.csic.es (M. Castillejo).