Experimental Study of Hydroxyl Stretching in Aluminosilicate Glass Cooled from High Temperature at Variable Quench Rates

Abstract

The physical properties of natural silicate magma are strongly influenced by the dissolution of water into the aluminosilicate melt framework. Of note is the presence of hydroxyl species (X-OH) that break apart the rigid silicate framework. Glass scientists observe an unusual broad absorption band associated with the stretching of hydroxyl species near 3500 cm-1 in the infrared spectra of water-bearing glasses. In an earlier study, we deconvolved this broad O-H stretching band into seven universal bands at uniform 150 cm-1 intervals in both natural and artificial aluminosilicate glasses. Our observation questions the standard explanation, that variable degrees of hydrogen bonding cause the unusual ‘low-energy tail’ of the prominent broadband absorption. We suggest that the low-energy tail results from the interaction of photons with a series of vibrational modes preserved in the glass at quantum states that differ by 1.8 kJ/mol. In this study, we present the results of an experimental study on water-rich, natural obsidian glasses quenched from high temperatures within cold-seal pressure vessels. We characterize the infrared absorption features in glasses cooled at quench rates varying by several orders of magnitude. Our results further our understanding of the nature of absorption bands associated with dissolved water in silicate glass.