Laser ablation-ICP-MS depth profiling to study ancient glass surface degradation

Abstract

In general the analysis of archeological glass represents a challenge for a wide variety of objects because of the presence of physical and/or chemical damage on the surface of the artifact, also known as weathering or corrosion. To retrieve accurate bulk elemental information by laser ablation-inductively coupled plasma-mass spectrometry (ICP-MS), the original, pristine glass needs to be "reached", thereby penetrating the alteration layer which is often more than 10 μm thick. To study this alteration layer the laser was operated in the drilling mode, either with a low (1 Hz) or a high (10 Hz) pulse repetition rate for a period of 50 s yielding detailed spatial information for ca. 20 elements over a shallow depth (ca. 5 μm) or less-detailed spatial information for 50-60 elements over a greater depth (ca. 50 μm). Quantitative elemental depth profiles (in wt%) were obtained with the so-called sum normalization calibration protocol, based on summation of the elements as their oxides to 100 wt%. We were able to associate the increase of SiO2 (in wt%) in the alteration layer to the volumetric mass density change in the glass as a result of depletion of Na2O and K2O. Also the interaction of the number of laser shots with the alteration layer is shown experimentally via depth measurements using profilometry. Chemical and physical changes in four ancient glass artifacts, directly and indirectly measureable by laser drilling, were studied as a function of internal and external factors such as age, composition, and exposure conditions.

Combined LA-ICP-MS/LIBS: powerful analytical tools for the investigation of polymer alteration after treatment under corrosive conditions

“…LA-ICP-MS is an analytical technique commonly reported in the literature for elemental depth profiling experiments 54 , 55 but has, to our knowledge, never been employed to investigate the uptake of corrosive species in polymers. In this section, we present LA-ICP-MS as a powerful analytical tool to investigate sulfur uptake within polyimides after weathering experiments.…”

Effect of soil pH on the degradation of silicate glasses

“…The width of the fissures, and consequently the percentage surface area that was degraded, depended on the soil pH ( Figure 10). Historical soda lime silicate glasses usually present dealkalization layers on their surface but this was not observed in these tests, 6,9,[41][42][43] this could be due to the high chemical durability of soda lime silicate glasses meaning that more time is need to produced such layers. According to literature, the dissolution of silica in aqueous solutions takes place on pH 9 or above.…”

“…This is the main reason that a large number of ancient glass objects have been preserved until today. [6][7][8][9] The degree of alteration of ancient glass and the mechanisms involved in that alteration are useful information for two subjects of study: (i) historical analysis of either the typological and/or aesthetic aspects of glass objects and for the historical characterization from a material science perspective; and (ii) the development of conservation strategies for the chemical stabilization of glass objects following excavation and their proper preservation for the future. 1,2 Despite the chemical durability of these glasses, which mainly depends on their composition, 3 degradation does occur during burial, albeit at a very slow rate.…”

“…4,5 The most common degradation pathologies that result from burial affect the surfaces, producing dealkalization layers, pits, craters, and other corrosion products. [6][7][8][9] The degree of alteration of ancient glass and the mechanisms involved in that alteration are useful information for two subjects of study: (i) historical analysis of either the typological and/or aesthetic aspects of glass objects and for the historical characterization from a material science perspective; and (ii) the development of conservation strategies for the chemical stabilization of glass objects following excavation and their proper preservation for the future. 10,11 Degradation of glass depends on its chemical composition and its surrounding environmental conditions.…”

High-speed and high-resolution 2D and 3D elemental imaging of corroded ancient glass by laser ablation-ICP-MS

“…While being a wellestablished analytical technique for the characterisation of ancient glass, [15][16][17] its use remains mostly limited to obtaining the bulk chemical composition of the (unaltered) substrate, whereas published studies in which this technique is used to specically study the surface degradation are scarce. [18][19][20] LA-ICP-MS analysis is based on the direct micro sampling of a solid volume and the subsequent elemental analysis of the generated material via a mass spectrometry detector. It is considered a "quasi" non-destructive (or micro-destructive) technique, requiring minimal or no sample preparation, while providing higher sensitivity/lower detection limits (in the ng g −1 range) compared to more conventional techniques used for glass characterisation.…”