Interfacial water is ubiquitous in nature and technology. Understanding the behavior of water at an interface is crucial as many chemical, biological, geological reactions take place at the interface such as heterogeneous catalysis, protein folding, mineral dissolution etc. One of the most promising areas of research involves understanding how interfacial water governs the chemistry occurring at various geologically significant mineral oxide surfaces. It is widely known that at ambient conditions, depending upon the pH of the solution the terminal hydroxyl groups at aluminum oxide surfaces can be either protonated (positively charged) or deprotonated (negatively charged). Previously, OH stretch studies have shown that the bulk pH and presence of electrolyte in the solution have a profound effect on the structure, orientation and vibrational dynamics of interfacial water molecules. The present work involves the use of Stark active molecules to directly study the interaction between electrolyte molecules and mineral oxide surfaces. Here, the heterogeneous charge density at Al2O3 (0001) surface is investigated by probing the Stark active CN stretch of SCN- molecular ions. Nonlinear spectroscopic techniques which are inherently surface specific, including steady state and time resolved vibrational sum frequency generation spectroscopy, were used. The vibrational lifetime observed for the CN stretch at Al2O3/H2O interface is very fast (fs time scale) as the bend + libration mode of H2O (~2130 cm-1) provides an effective way to transfer energy. At the Al2O3/D2O interface, this combination band is not available and a slower vibrational relaxation time (ps time scale) is observed for the CN stretch.

Insights on the interfacial structure and dynamics of Al2O3(0001)/D2O interface by probing the Stark active SCN- molecular ions

Macromolecular Chemistry: The Second Century

[Author Benefits](https://scimeetings.acs.org/?utm_source=pubs_content_marketing&utm_medium=website&utm_campaign=0320_MCF_NPI_Launch_Spring_Homepage&ref=pubs_content_marketing)

[How to use SciMeetings](https://storage.googleapis.com/dl.morressier.com/acs/SciMeetings-ACSSpring2020-HowToGuide_M3020-Final.pdf)

[Frequently Asked Questions](https://storage.googleapis.com/dl.morressier.com/acs/SciMtng_ACSNMSp2020_FAQ_M3120_Final.pdf)

ACS Spring 2020 National Meeting & Expo

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