RUI: Thermodynamics of Nucleation: Pathways to Atmospheric Aerosols

The Environmental Chemical Sciences Program in the Division of Chemistry supports Professor George Shields at Furman University, Greenville, SC, and his students will work on a computational study to better understand the energetics of molecular clusters in the atmosphere which can subsequently form particles that are involved in cloud formation. Understanding the beginning stages of cloud formation is important because some clouds reflect sunlight back into space and help cool the Earth.

Professor Shields will work with 12 undergraduate students for 10 weeks during the summers of 2025-2027. The undergraduate students will take part in a three-week program at the start of the summer that combines the beginning stages of research with modules taught by the faculty on various activities essential for the research enterprise. They also take part in a Pathway Program, which prepares them for graduate school or industrial careers.

In addition, a postdoctoral associate will learn how to mentor undergraduate research students and work closely with the PI throughout this project.

In this project the researchers will optimize their processes for calculating highly accurate Gibbs free energy changes for the formation of prenucleation clusters from acids, bases, and other molecules that are present in the atmosphere. Results will be used to establish probable pathways for formation of prenucleation clusters using the Gibbs free energy values and a range of initial atmospheric concentrations for each of the monomers.

The two acids believed to be responsible for most particle formation over land and ocean, sulfuric and methanesulfonic acids, will be directly compared to gain insight on these processes. The researchers will also compare the anionic systems sulfate and bisulfate interactions with water, to compare their calculated energies with the values in existing database.

Cation systems will also be explored so as to compare experimental work using mass spectrometry with the theoretical results. The synergy between experiment and computation will reveal much about the process of formation of prenucleation complexes.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.