RUI: Thermodynamics of Nucleation: Atmospheric Aerosols from Acids, Bases, and Peptides

Furman University, Greenville SC

Investigators

Abstract

Professor George Shields of Furman University is supported by the Environmental Chemical Sciences Program of the Division of Chemistry and the Atmospheric Chemistry Program of the Division of Atmospheric and Geospace Sciences. The goal of the project is to examine properties of molecular complexes in the atmosphere. These molecules are formed from water molecules, sulfuric acid molecules, and other trace molecules. Such molecules are important because they are fundamental to how particles, and from these, clouds, form. The mechanism for the start of cloud formation is currently not well-understood. Undergraduate students carry out the research and gain experience in chemical modeling for several years. The team includes female students and students from underrepresented minorities. A post-doctoral associate participates in the research and the mentoring of the undergraduate students. Professor Shields has a long-standing collaboration with researchers working with undergraduate research groups, known as MERCURY. Historically, about half of the undergraduate students from these cohorts attend graduate school. The quantum chemical calculations determine the minimum energy structures, thermodynamics for formation, and relative abundance of molecular clusters. Clusters that serve as neutral and ionic cloud condensation nuclei contain acids, bases, and water. The acids considered are sulfuric acid, formic acid, and amino acids. The bases include ammonia and amines. The work combines a genetic algorithm for configurational sampling with efficient high-level quantum chemical methods that have been computationally expensive for systems of this size until now. The calculated trends in thermodynamics of cluster formation are compared with experimental nucleation rates. 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.