In this award, funded by the Chemical Structure, Dynamics and Mechanisms (CSDM) Program of the Chemistry Division, Prof. Alexander V. Benderskii of the University of Southern California and his graduate, undergraduate, and postdoctoral research students will use surface-selective nonlinear optical spectroscopy techniques to learn about the molecular structure and dynamics at liquid interfaces, in particular the nature of the hydrogen bonding. Conceptually, it is the asymmetry of the interfacial environment and the resulting anisotropic interactions that make interfaces fundamentally different from bulk liquids. The goal of this research is to understand the dynamic behavior, and relaxation mechanisms of the aqueous H-bond network of the interfacial water. To achieve this goal, spectroscopic studies will be performed using vibrations of the water molecule itself (OH stretch and bend modes) that report on the dynamics of the H-bonding environment, as well as rotational relaxation measurements of small probe molecules that report on the local microscopic friction and the molecular origins of viscosity.
The properties of water in the thin interfacial region underlie important processes such as solvation, hydration, hydrodynamic drag, wetting, and amphiphilic self-assembly. This has profound implications in biology, biomedical sciences, bioengineering, where the molecular properties of the thin layer of 'biological water' critically affect biochemical and biophysical processes occurring in the interfacial region. The mechanistic aspect of the relaxation processes and the molecular origins of viscosity have direct applications in hydrodynamics and microfluidics. The research will stimulate theoretical developments and lead to better computational models for aqueous and biological interfaces. Teaching and training students at all levels, undergraduate, graduate, and postdoctoral will be an integral part of this project. The educational, training, and outreach activities will include underrepresented minorities in the greater Los Angeles metropolitan area, as well as postdoctoral research student mentoring.
