Vibrational Dynamics at Aqueous–Mineral Interfaces

Abstract

The dynamics of water at mineral surfaces has attracted much attention due to the marked differences, compared to the bulk, in the ability of interfacial water populations to redistribute vibrational energy, largely due to perturbations in the local hydrogen-bonding environments at interfaces. However, many unanswered questions persist regarding these geochemically and technologically relevant systems. The evolution of our understanding and current state-of-the-art interpretation are reviewed for three important mineral/aqueous interfaces (Al2O3, SiO2, and CaF2). While we focus on time-resolved vibrational Sum Frequency Generation (vSFG), as it is inherently surface specific, we include complementary time-resolved techniques such as IR and THz spectroscopies, which combined can provide a broader picture of interfacial dynamics at mineral surfaces. We show that vibrational dynamics are uniquely positioned to inform on structure at interfaces, which could be missed using conventional static vibrational spectra. Insights presented here shine light on previous successes and suggest future avenues for transient vibrational spectroscopy at mineral/aqueous interfaces.