IAS Distinguished Lecture - Radical Chemistry Across Interfaces

Abstract

The chemistry of our atmosphere is shaped not only by reactions in the gas phase but also by processes at interfaces that control reactivity in unexpected ways. Radicals such as OH, HO₂, and chlorine, long recognized as central to ozone depletion and oxidative balance, behave differently at the surfaces of cloud droplets, aerosols, and other condensed phases. Interfaces can align radicals, lower barriers, and accelerate reactions by orders of magnitude, producing pathways absent in the gas phase. These effects provide explanations for unresolved problems ranging from the efficiency of sulfur oxidation and acid rain formation to the persistence and recycling of chlorine in the stratosphere. By integrating computational modeling with experimental observations, the speaker reveals a consistent picture: not all chemistry in the atmosphere is gas-driven, interfacial chemistry is not peripheral but fundamental to atmospheric processes. Recognizing this interfacial control reshapes how we understand the chemical resilience and vulnerability of Earth’s atmosphere.


About the Speaker

Prof. Joseph S. FRANCISCO is the President's Distinguished Professor of Earth and Environmental Science and Professor of Chemistry at the University of Pennsylvania (UPenn). He received his bachelor’s degree from the University of Texas at Austin in 1977 and his doctorate from the Massachusetts Institute of Technology (MIT) in 1983. From 1983-85, Prof. Francisco trained as a Research Fellow at the University of Cambridge in England, and then returned to MIT as a Provost Postdoctoral Fellow. He had held various positions at Purdue University and Wayne State University prior to joining UPenn as faculty in the Department of Earth and Environmental Science and Department of Chemistry. He was also a Visiting Associate in Planetary Science at the California Institute of Technology.

Over his career to date, Prof. Francisco has published more than 801 journal articles, written several book chapters, and is co-author of a fundamental textbook, Chemical Kinetics and Dynamics, which has been considered a "classic" in the field for about 30 years. He is also the author of the forthcoming book, Atmospheric Chemistry, to be published by the Cambridge University Press. He was elected to several prestigious organizations, including the American Academy of Arts and Sciences, the US National Academy of Sciences, the American Philosophical Society, and the German National Academy of Sciences Leopoldina.

Prof. Francisco is currently an Executive Editor of the Journal of the American Chemical Society, and he has recently been appointed as a member of the Editorial Board for the Proceedings of the National Academy of Sciences of the United States of America. He has served on the US National Academy of Sciences Council and on the Governing Board of the US National Research Council. He currently serves on the American Academy of Arts and Sciences Council and the Board of Directors for the American Association for the Advancement of Science. He was President of the American Chemical Society in 2010.


For Attendees' Attention

Seating is on a first come, first served basis.