Vibrational spectroscopy of water at charged liquid/solid interfaces

Summary form only given. Many physical and chemical properties of water/solid oxide interfaces are linked to the isoelectric point of solid surfaces (IEPS). In this paper we have used SFG spectroscopy to monitor the structure of water molecules at water/sapphire interfaces. We have demonstrated that the interfacial water SFG signal intensities depend strongly on the total hydroxyl number density at the interface and showed that the water dipole flips by 180/spl deg/ when the pH of the solution crosses the IEPS of the substrate. The dependence of the SFG signal intensities on total charge density was used to determine the IEPS of non-conductive, low surface area materials.