Red lakes from Leonardo's Last Supper and other Old Master Paintings: Micro-Raman spectroscopy of anthraquinone pigments in paint cross-sections

Iacopo Osticioli; Marco Pagliai; Daniela Comelli; Vincenzo Schettino; Austin Nevin

doi:10.1016/j.saa.2019.117273

Red lakes from Leonardo's Last Supper and other Old Master Paintings: Micro-Raman spectroscopy of anthraquinone pigments in paint cross-sections

Spectrochim Acta A Mol Biomol Spectrosc. 2019 Nov 5:222:117273. doi: 10.1016/j.saa.2019.117273. Epub 2019 Jun 13.

Authors

Iacopo Osticioli¹, Marco Pagliai², Daniela Comelli³, Vincenzo Schettino², Austin Nevin⁴

Affiliations

¹ Institute of Applied Physics "Nello Carrara" National Research Council (IFAC-CNR), Via Madonna del Piano, 10, 50019 Sesto Fiorentino, Firenze, Italy.
² Dipartimento di Chimica "Ugo Schiff", Università degli Studi di Firenze, Via della Lastruccia 3, 50019 Sesto Fiorentino, Firenze, Italy.
³ Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, Milano 20133, Italy.
⁴ Istituto di Nanotecnologie e Fotonica National Research Council (IFN-CNR), Piazza Leonardo da Vinci 32, Milano 20133, Italy; Department of Conservation, University of Gothenburg, Box 130, 40530 Gothenburg, Sweden. Electronic address: austin.nevin@gu.se.

PMID: 31229919
DOI: 10.1016/j.saa.2019.117273

Abstract

The analysis of red particles in paint cross-sections from Leonardo da Vinci's Last Supper, Masolino da Panicale's wall painting Beheading of St. John the Baptist in Castiglione Olona, Tintoretto's The Discovery of the Body of Saint Mark and Paolo Veronese's Supper in the House of Simon has been carried out with micro-Raman measurements. Subtracted shifted Raman spectroscopy methods have been employed to resolve the signals in the presence of fluorescence. Taking advantage of the vibrational assignments based on recent ab initio calculations of aluminum-complexes of anthraquinones, the approach allowed the discriminate between anthraquinone dyes and lakes based on kermesic and carminic acids present in the studied samples for the first time without heavy sample treatment.

Keywords: Carmine; Cochineal; Kermes; Organic pigments; Raman microscopy.