In the last decade, Raman spectroscopy has been applied successfully to non-invasive characterization of ancient glass, allowing to differentiate composition and toexploreaspects as glass maker technology and dating [1-3]. One of the most used methods in the field of art and archaeology, proposed for the first time by Colomban et al. [4],isbased on the relation between the structure of silica glass and its Raman signature. In particular, the band arearatio (A500/A1000) of the Si-O bending - at 500 cm-1- and stretching - about 1000 cm-1- was proposed as polymerization index. Further information is obtained by the analysis of the wavenumberand relative amplitude of the different Si-O stretching components, related to the Qnunits constituting the glass. The method has been widely and successfully applied on numerous ancient glass [4 and references therein], providingan empirical approach to classify different "glassy silicate families". The aim of this work is to investigate the dependence of the Raman spectra of silica glasses on their compositions, fabrication procedures (fluxing agents and quenching environment) and on the experimental setup (kind of spectrometer and, mostly, excitation laser line). Their influence on the polymerization index and on the apparent changes on the Qn stretching bands is evaluated. For this scope, we created and analyzed a series of artificial glass samples (named SR1-14) resembling ancient Roman ones, with a compositional rangeshown in Fig. 1. The compositional data have been determined by EMPA analysis. Micro-Raman measurements have been performed on artificial glass by using different laboratory micro-Raman apparatus, with 632 to 473 nm excitation wavelengths, and a portable Raman with 532 nm excitation. Spectra have been processed in order to determine parameters as the polymerization index and Si-O bands frequencies and intensities. The obtained results have been therefore compared with reference glassand discussed on the basis of compositional data. Figure 1. Composition of artificial glass made resembling Roman ancient glass. SR1-2 : Na2O >>CaO + K2O; SR3-8:Na2O = CaO + K2O; SR 9-14: Na2O <<CaO + K2O. Quenching in oxidizing conditions. REFERENCES:[1]Colomban P.,Glasses, glazes and ceramics-recognition of the ancient technology from the Raman spectra. In Raman Spectroscopy in Archaeology and Art History, Edwards HGM, Chalmers JM (eds). Royal Society of Chemistry: London, 2005; 192, Chapt. 13. [2] Colomban, P., Tournie, A., Bellot-Gurlet, L.,J. Raman Spectrosc. 37 (2006) 841-852 [3] Colomban, P., Journal of Cultural Heritage 9 (2008) e55-e60 [4] Colomban, P., J. Non-Crystalline Solids 322 (2003) 180-187.
ON THE FOOTSTEPS OF THE ANCIENT GLASS MAKERS: TOWARD AN EXPERIMENTAL GLASS CLASSIFICATION BY USING RAMAN SIGNATURE BASED ON ROMAN GLASS REPLICAS
Raneri Simona
;Masotta Matteo;Lezzerini Marco;Bersani Danilo
2018-01-01
Abstract
In the last decade, Raman spectroscopy has been applied successfully to non-invasive characterization of ancient glass, allowing to differentiate composition and toexploreaspects as glass maker technology and dating [1-3]. One of the most used methods in the field of art and archaeology, proposed for the first time by Colomban et al. [4],isbased on the relation between the structure of silica glass and its Raman signature. In particular, the band arearatio (A500/A1000) of the Si-O bending - at 500 cm-1- and stretching - about 1000 cm-1- was proposed as polymerization index. Further information is obtained by the analysis of the wavenumberand relative amplitude of the different Si-O stretching components, related to the Qnunits constituting the glass. The method has been widely and successfully applied on numerous ancient glass [4 and references therein], providingan empirical approach to classify different "glassy silicate families". The aim of this work is to investigate the dependence of the Raman spectra of silica glasses on their compositions, fabrication procedures (fluxing agents and quenching environment) and on the experimental setup (kind of spectrometer and, mostly, excitation laser line). Their influence on the polymerization index and on the apparent changes on the Qn stretching bands is evaluated. For this scope, we created and analyzed a series of artificial glass samples (named SR1-14) resembling ancient Roman ones, with a compositional rangeshown in Fig. 1. The compositional data have been determined by EMPA analysis. Micro-Raman measurements have been performed on artificial glass by using different laboratory micro-Raman apparatus, with 632 to 473 nm excitation wavelengths, and a portable Raman with 532 nm excitation. Spectra have been processed in order to determine parameters as the polymerization index and Si-O bands frequencies and intensities. The obtained results have been therefore compared with reference glassand discussed on the basis of compositional data. Figure 1. Composition of artificial glass made resembling Roman ancient glass. SR1-2 : Na2O >>CaO + K2O; SR3-8:Na2O = CaO + K2O; SR 9-14: Na2O <I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
