Laser spectroscopies for elemental and molecular analysis in art and archaeology

Abstract

Spectroscopic methods using laser sources have significantly improved our capacity to unravel the chemical composition of works of art and archaeological remains. Lasers enhance the performance of spectroscopic techniques which require intense light sources and specific analytical protocols assuring a microanalytical approach for analysis has been established. This review focuses on laser spectroscopic methods used in the field of cultural heritage diagnostics. Emphasis in this work is given to the analytical capabilities of laser-based techniques for elemental and/or molecular analysis and in-situ use, spatial resolution and microanalysis. Analytical methods are classified according to the elemental (LIBS, LA–ICP–MS) and molecular (LIF/LIDAR, time-resolved absorption spectroscopy, laser desorption ionization mass spectrometry) information they yield. For non-destructive laser-induced fluorescence (LIF/LIDAR) and time-resolved fluorescence spectroscopy, imaging applications are described. The advantages provided by combined complementary techniques including but not limited to LIBS–LIF–Raman and LIBS–XRF are presented, as are recent improvements in terms of chemical imaging. Advances and applications of THz spectroscopy, non-linear spectroscopy and imaging are outlined. Finally, laser spectroscopies are described for investigations of different materials and works of art which include Bronze Age ceramics, Minoan archaeological remains, Ancient Roman buildings, Renaissance wall paintings and sculptures, and manuscripts containing iron gall inks and colorants.