Shining light on the interface: From metallomembranes to hydrophobic droplets in water

DIPC Seminars

Saranya Pullanchery
EPFL, Switzerland
Hybrid Seminar: Donostia International Physics Center
Aitzol García-Etxarri
Add to calendar


Subscribe to Newsletter
Shining light on the interface: From metallomembranes to hydrophobic droplets in water

Aqueous interfaces are ubiquitous in nature. An interface's chemical and physical properties are intricately linked to the organization of the first few molecular layers at the surface. Characterizing this interfacial molecular structure is a challenging task because one has to separate the few layers of molecules at the interface from the bulk. Vibrational sum frequency generation spectroscopy, a second-order nonlinear optical technique, has emerged as a unique tool with exquisite interface selectivity to characterize the vibrational structure of molecules at interfaces. In this seminar, I will demonstrate two examples of the implementation of this technique to understand the molecular mechanism of chemical processes at interfaces. In the first part, I will discuss the molecular mechanism of interaction between divalent cations and negatively charged model lipid membranes, and the molecular details of ion specificity. In the second part, I will demonstrate how water is not just a passive medium but can directly influence the chemical properties of an interface with the example of hydrophobic droplets in water. Hydrophobic droplets acquire a negative charge when in contact with water. The origin of this negative charge has been debated for over a century. Using vibrational sum frequency scattering, we revealed the molecular mechanism of this interfacial charging phenomenon.