March 10, 2004
Director of Media Relations

AMHERST, Mass.-Mark Marshall and Helen Leung, professors of chemistry at Amherst College, are among the authors of a recent paper that explored the bond between the hydroxyl radical (HO) and water (H2O). In a recent issue of Chemical & Engineering News it was reported that "Atmospheric chemists, in particular, find H2O-HO interesting, as the HO radical oxidizes organic pollutants and may also play a role in the chemistry of earth's ozone hole." "The hydroxyl radical is like nature's detergent," Marshall says. The research also demonstrates the intrinsically quantum mechanical nature of this species and provides evidence for the changes in the electronic environments of the molecules that signal the start of a chemical reaction.

Marshall and Leung study the detailed structure and dynamics of small molecules and chemical complexes. This research, first reported online in Chemical Physical Letters last December and appearing in print in January, examined the manner in which the extremely reactive hydroxyl radical (OH) interacts with potential reaction partners such as water. The hydroxyl radical, a powerful oxidant, is maligned for the damage it can cause in biological systems such as the human body, but is also capable of reactions that remove pollutants such as volatile organic compounds (VOCs) from the atmosphere. Since water is ubiquitous in living things and in the atmosphere, chemists have speculated on the importance of the chemistry of an H2O-HO radical complex, in atmospheric science, genetics and other fields.

Leung received both B.S. and B.A. degrees from California State University, Northridge and a Ph.D. from Harvard University. She was a postdoctoral fellow at the Harvard-Smithsonian Center for Astrophysics. Leung has taught at Amherst since 2002. Marshall, a member of the Amherst College faculty since 1987, received a B.S. degree from the University of Rochester and Ph.D. from Harvard University, and was a postdoctoral fellow at the National Research Council, in Ottawa, Canada.

The H. Axel Schupf '57 Fund for Intellectual Life supported Marshall during a sabbatical year at the University of Pennsylvania while he worked on this project. Both Leung and Marshall have received a Henry Dreyfus Teacher-Scholar Award. A National Science Foundation grant to Amherst College also supported the work.