title: Micro-Laser-Induced Breakdown Spectroscopy (Micro-LIBS) Study on Ancient Roman Mortars.
abstract: The laser-induced breakdown spectroscopy (LIBS) technique was used for analyzing the composition of an ancient Roman mortar (5th century A.D.), exploiting an experimental setup which allows the determination of the compositions of binder and aggregate in few minutes, without the need for sample treatment. Four thousand LIBS spectra were acquired from an area of 10 mm2, with a 50 µm lateral resolution. The elements of interest in the mortar sample (H, C, O, Na, Mg, Al, Si, K, Ca, Ti, Mn, Fe) were detected and mapped. The collected data graphically shown as compositional images were interpreted using different statistical approaches for the determination of the chemical composition of the binder and aggregate fraction. The methods of false color imaging, blind separation, and self-organizing maps were applied and their results are discussed in this paper. In particular, the method based on the use of self-organizing maps gives well interpretable results in very short times, without any reduction in the dimensionality of the system.
authors.affiliation: 1 Applied and Laser Spectroscopy Laboratory, Institute of Chemistry of Organometallic Compounds, Research Area of National Research Council, Pisa, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Pagnotta
authors.affiliation: 2 Department of Earth Sciences, University of Pisa, Pisa, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Lezzerini
authors.affiliation: 3 Department of Analytical Chemistry and Food Science, University of Alicante, Alicante, Spain.
authors.forename: Laura
authors.initials: L
authors.lastname: Ripoll-Seguer
authors.affiliation: 3 Department of Analytical Chemistry and Food Science, University of Alicante, Alicante, Spain.
authors.forename: Montserrat
authors.initials: M
authors.lastname: Hidalgo
authors.affiliation: 1 Applied and Laser Spectroscopy Laboratory, Institute of Chemistry of Organometallic Compounds, Research Area of National Research Council, Pisa, Italy.
authors.forename: Emanuela
authors.initials: E
authors.lastname: Grifoni
authors.affiliation: 1 Applied and Laser Spectroscopy Laboratory, Institute of Chemistry of Organometallic Compounds, Research Area of National Research Council, Pisa, Italy.|4 National Interuniversity Consortium of Materials Science and Technology (INSTM), Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Legnaioli
authors.affiliation: 1 Applied and Laser Spectroscopy Laboratory, Institute of Chemistry of Organometallic Compounds, Research Area of National Research Council, Pisa, Italy.
authors.forename: Giulia
authors.initials: G
authors.lastname: Lorenzetti
authors.affiliation: 1 Applied and Laser Spectroscopy Laboratory, Institute of Chemistry of Organometallic Compounds, Research Area of National Research Council, Pisa, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Poggialini
authors.affiliation: 1 Applied and Laser Spectroscopy Laboratory, Institute of Chemistry of Organometallic Compounds, Research Area of National Research Council, Pisa, Italy.|4 National Interuniversity Consortium of Materials Science and Technology (INSTM), Italy.
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Palleschi
keywords: LIBS; Laser-induced breakdown spectroscopy; aggregate; artificial neural networks; binder; blind separation techniques; mortars; self-organizing maps