"On the fiber" SERS detectino of synthetic dyes employing laser photoreduced Ag nanoparticles

TECHNART 2015 − Catania, April 27 - 30, 2015; http://technart2015.lns.infn.it/Micro- or non-destructive identification of synthetic organic dyes employed to color cultural heritage objects such as historical textiles, is a real challenge for conservator scientists. Surface-enhanced Raman scattering (SERS) has been developed as a micro or non-destructive technique for the characterization of organic dyes in works of art [1]. The application of Ag nanoparticles produced by laser photoreducion [2], lead us to test the possibilities of such method for the ¿on the fiber¿ SERS detection of synthetic organic dyes. In this work, wool fibers dyed with triarylmethane, xantene or monoazo dyes were investigated. Ag nanoparticles were prepared and immobilized directly on wool fibers by photoreduction of AgNO3 using a laser/micro-Raman coupled system [3] at different experimental conditions, such as excitation wavelength, laser power and irradiation time. In order to achieve good ¿on the fiber¿ SERS spectra without burning the sample, two different experimental methods have been developed using two excitation wavelengths (442 nm and 532 nm). The main novelty of this research consists on the development of a versatile photoreduction method. It was found that photoreduced Ag nanoparticles obtained at 442 nm allowed the analysis of the dyed fibers with different excitation wavelengths (442 nm, 532 nm, 785 nm), thus improving the identification of the dye. [1] F. Casadio, M. Leona, J.R. Lombardi, R. Van Duyne, Accounts of Chemical Research, 43 (6), 2010, 782. [2] M. V. Cañamares, J.V. Garcia-Ramos, J.D. Gomez-Varga, C. Domingo, S.Sanchez-Cortes, Langmuir, 23, 2007, 5210. [3] Z. Jurasekova, C. Domingo, J.V. Garcia-Ramos, S. Sanchez-Cortes, Journal of Raman Spectroscopy, 39 (10), 2008, 1309.Peer Reviewe