Second Harmonic Generation (SHG) using a femtosecond Ti:sapphire oscillator was employed to determine points of zero charge (PZC) of centrosymmetric SrTiO3 perovskite and non-centrosymmetric z-cut alpha quartz. The interfaces of these materials in contact with water were studied with varying bulk water pH and NaCl concentration. For the SrTiO3 perovskite, we found that the surface is positively and negatively charged below and above pH 10, respectively. We also found that increasing NaCl concentration impacts SHG response by a combination of changing the ordering of water molecules at the interface with SrTiO3 and the depth of sampling the nonlinear optical response. For the non-centrosymmetric quartz, the SHG signal from the bulk was dominant over that from the interface. The rotational dependence of quartz SHG was collected to reveal the interfacial response. In this case, the surface was found to be neutral in the acidic pH range of 2-4. These results enable us to explore a wide range of oxides with the purpose of understanding the in-situ surface behavior of these materials.

Determination of point of zero charge of perovskites and oxides using second harmonic generation

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.