Atmospheric Chemistry Program Seminar: Guy Symonds, and Nicole Silver, CU ANYL Chem

The Ice Nucleating Properties of Southern Great Plains Mineral Dusts
Guy Symonds,
ANYL 1st year, CU Boulder
"Mixed phase clouds, a collection of supercooled liquid and frozen water droplets, are potentially important regulators of the Earth’s climate. In the troposphere, water droplets are primarily frozen through the immersion-mode freezing mechanism, where a rare particle within the droplet acts as a template and catalyzes the production of the ice phase. Commonly, these ice nucleating particles in the atmosphere are some type of suspended mineral dust. The research being presented examines the ice nucleating behavior of previously unprobed dust samples in the Southern Great Plains area in Oklahoma, United States of America. This location was subject to a field campaign due to its isolation from major industrial activity on the North American continent and so it serves as a “Continental background site”. By examining the ice nucleating activity of these dusts, the contribution to ambient aerosol in the Southern Great Plains area can be determined, as well as their relative contribution to total aerosol ice nucleating activity. Furthermore, these dusts were subjected to aging processes designed to simulate environmental weathering processes to further investigate the variability of their ice nucleating activity and how their freezing properties correlate with chemical changes caused by the aging."
and
Formation of a Polariton Through the Creation of Micro Cavities with an Active Layer of PFO
Nicole Silver,
ANYL 1st year, CU Boulder
"The presence of an exciton polariton, a quasiparticle formed through the strong coupling between a photon and an electron hole pair, creates important properties that have the potential to significantly increase the absorption efficiency of organic semiconductor materials in a solar cell. In my undergraduate research at Cornell University in Andrew Musser’s Light Matters Research Group, I focused on finding evidence of a polariton in the organic semiconductor material Perfluorooctanesulphonate (C8F17O3S), also known as PFO. This presentation will outline the intricate process of forming micro cavities, which involves the development of a spin coating technique and identification of several parameters specific to the polymer PFO. These are determined through absorption spectroscopy, profilometry, evaporation in vacuum, angle dependent reflectivity, and simulations. The process of creating a micro cavity and using an angle dependent reflectivity goniometer to discover two polariton branches in a PFO micro cavity will be discussed along with the identification of polariton branches in two other materials, TM82 and TM83."