During his second year at Hamilton, Tim Evans '05 took a sophomore seminar titled "The Natural and Cultural History of the Adirondack Park." During that class, he investigated acid rain in many ways, including its chemical formation, its effect on aquatic ecosystems, and government policy solutions to the acid rain problem. That class inspired Evans to further study the physical aspect of acid rain formation. He now has the chance to model the reactions with computers.
Evans is working this summer on expanding a 20-year-old chemistry theory that deals with the formation of acid rain. While working under the advisement of Winslow Professor of Chemistry George Shields, Evans will "find other examples in which clusters of gaseous water catalyze atmospheric sulfur reactions" other than in the reaction between sulfur trioxide and water in his project, "Effect of water clusters on the biogeochemical sulfur cycle."
| Summer Research 2004 |
As Evans investigates the catalytic effects of clusters of water into important sulfur reactions, he hopes that by doing so computationally, the experiment "will reduce discrepancies between theory and experiment." Specifically, Evans is investigating stable structures of carbon disulfide (OCS) bound with differently-sized water clusters. He is also working on modeling the atmospheric reaction between OCS and an oxygen atom to see if this reaction can be catalyzed with water clusters.
Evans explained why the reactions are so important by referencing a study done 20 years ago, which proved "adding a second water to the gas-phase reaction between sulfur trioxide and water to form sulfuric acid would almost eliminate the activation energy barrier of the last step in acid rain formation." He hopes that this computational project will find other examples in which clusters of gaseous water catalyze atmospheric sulfur reactions. Evans is not working alone on this project. Aside from the advisement of Professor Shields, five of Evans' colleagues are also pursuing the study of water clusters. Mary Beth Day '07 has submitted a paper to the International Journal of Quantum Chemistry on work she has done on larger water clusters named Octamers, and Meghan Dunn, a George Washington State University student, has published a paper in JACS that was the first foray into atmospheric chemistry done in the Hamilton College laboratory. Three of Hamilton's incoming first-year students, Dan Tomb '08, Greg Hartt '08 and Philip Holdredge '08, are investigating the structures and reactions of the hydroxyl radical, sulfur dioxide, carbon disulfide, hydrogen sulfide, and dimethylsulfide.
Evans claims the most difficult part of his research has been familiarizing himself with the supercomputer system and some advanced modeling software. Mastering UNIX has also caused Evans a bit of difficulty. However, dealing with the technology this summer will make his fall semester much easier, as Evans plans to continue this project in the fall as his senior thesis project in chemistry. Evans says that his project in the fall will involve "a more global investigation of the biogeochemical sulfur cycle."
--by Emily Lemanczyk '05
