Probing the Mineral–Water Interface with Nonlinear Optical Spectroscopy

• Published in: Angewandte Chemie International Edition Vol. 60; no. 19; pp. 10482 - 10501
• Main Authors: Backus, Ellen H. G., Schaefer, Jan, Bonn, Mischa
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 03.05.2021; John Wiley and Sons Inc
• Edition: International ed. in English
• Subjects: alumina; calcium fluoride; Dissolution; Interfaces; Ions; Minerals; Nonlinear optics; Review; Reviews; Second harmonic generation; silica; Spectroscopy; Spectrum analysis; vibrational spectroscopy; Water chemistry; Wetting; nonlinear optics; vibrational spectroscopy; alumina; calcium fluoride; silica
• ISSN: 1433-7851; 1521-3773; 1521-3773
• DOI: 10.1002/anie.202003085

The interaction between minerals and water is manifold and complex: the mineral surface can be (de)protonated by water, thereby changing its charge; mineral ions dissolved into the aqueous phase screen the surface charges. Both factors affect the interaction with water. Intrinsically molecular‐level processes and interactions govern macroscopic phenomena, such as flow‐induced dissolution, wetting, and charging. This realization is increasingly prompting molecular‐level studies of mineral–water interfaces. Here, we provide an overview of recent developments in surface‐specific nonlinear spectroscopy techniques such as sum frequency and second harmonic generation (SFG/SHG), which can provide information about the molecular arrangement of the first few layers of water molecules at the mineral surface. The results illustrate the subtleties of both chemical and physical interactions between water and the mineral as well as the critical role of mineral dissolution and other ions in solution for determining those interactions. The interaction between minerals and water is relevant for a wide range of geological, atmospheric, environmental, and electro(photo‐)chemical systems. This Review highlights the developments made through studying a variety of mineral–water interfaces by nonlinear optical spectroscopy. These methods provide molecular‐level details about the organization of water in the direct vicinity of the interface.