Abstract:
The present PhD project aims to study a wide selection of glass artifacts from different periods, in order to obtain information on their chemical composition, to trace back their raw materials, to advance hypotheses on their geographic origin and technology and to investigate the phenomena of degradation. Among the various analytical techniques, LA-ICP-MS (laser ablation inductively coupled plasma mass spectrometry) seems to be ideally suited for the analysis of glass due to its high sensitivity (detection limits in the ng g-1 range for some elements) and large linear range (9-10 orders of magnitude), whereas very little or no sample preparation is necessary. Since LA-ICP-MS is a microanalytical technique for direct solid sampling of solid material (via a high-energy, pulsed laser beam of several µm to several hundreds of µm in size), it may be considered "quasi" non-destructive.
The study is divided in different but complementary steps since several approaches are necessary to acquire a complete “picture” of the chemical composition of glass and the phenomena related to the degradation of glass. Laser ablation can be executed in different modes, i.e. ablation on a spot (drilling) or along a line (line scan or raster mode) for retrieval of multi-elemental concentrations in the bulk, depth profiles and elemental maps. Using various laser ablation modes spatial information (lateral resolution of several µm and depth resolution as low as 150 nm) could be obtained for up to ca. 60 (major, minor and trace) elements simultaneously. The laser ablation ICP-MS data can be combined with data from other analytical techniques, e.g. EPMA or UV-Vis spectroscopy, in order to obtain supplementary information related to the material. A selection of different archaeological, historical and artificially aged glasses were analysed by laser ablation ICP-MS (and other techniques) in order to obtain quantitative elemental bulk concentrations, depth profiles and 2D and 3D maps related to the different raw materials used for glass fabrication, glass degradation phenomena, heterogeneity, etc.
