Speaker
Prof.
Heather Allen
(Ohio State University)
Description
The air-water interface has been the focus of research in
the Allen Lab at Ohio State for more than a decade. We
utilize nonlinear and linear optical spectroscopic methods
to understand the local intermolecular interactions and
organization of water itself with various solutes and
monolayers. Motivated by atmospheric aerosol chemistry of
marine and urban regions, and biophysical applications
related to lung lining and biomembranes, monovalent and
divalent cations and anions continue to be investigated by
our group using conventional and heterodyne-detection
vibrational sum frequency generation (VSFG) spectroscopy.
Interest is in the surface propensity and availability for
reaction at water surfaces. Ion valency, polarizability,
size, shape, and identity of the counterion are critical
factors in considering ion organization and subsequent
changes in interfacial electric field at the air water
interface. The hydrating water molecules play a key role in
the interfacial organization of other species in the
solution, and is studied directly as it reveals the details
of ion interfacial distributions. Phospholipids and fatty
acids are also investigated using both VSFG and Brewster
angle microscopy (BAM). Head group differences, especially
with regard to hydrogen bonding capability and extent, are
discerning factors for surface organization and shape
distinction at the water surface.
