Princeton American Chemical Society Section Presents

”Water in the Atmosphere: The Molecule that Changes Everything”

Princeton University, Frick Chemistry Laboratory
Tuesday, December 9, 2025

Mixer and refreshments, outside of Frick Auditorium       6:30 pm

Seminar and Discussion, Frick Auditorium       7:00 pm

Our speaker will be Joseph Francisco, PhD, Department of Earth and Environmental Science and Department of Chemistry, University of Pennsylvania

 Abstract: Water is one of the most abundant resources in our atmosphere and, because of its ability to be both a hydrogen bond donor and acceptor, water can form very stable new chemical species, not considered in the chemistry of the atmosphere before. These new chemical entities can dramatically affect the chemistry in the atmosphere, including heterogeneous removal and alteration of the photochemical properties of the atmospheric species. It also provides fundamental new insight into chemistry on clouds that have never been imagined – turning clouds into mini-chemical reactors. An overview of both experimental and theoretical investigations of water effects on gas phase reactions will be made, with the goal of providing an understanding of new fundamental concepts underlying water effects on reactions in our atmosphere.

Bio Sketch: Joseph S. Francisco is the President’s Distinguished Professor of Earth and Environmental Science and Professor of Chemistry at the University of Pennsylvania. He received his bachelor’s degree from the University of Texas at Austin in 1977 and his doctorate from Massachusetts Institute of Technology in 1983. From 1983-85, Francisco trained as a Research Fellow at the University of Cambridge in England and then returned to MIT as a Provost Postdoctoral Fellow. He was also a Visiting Associate in Planetary Science at the California Institute of Technology. Over his career to date, Francisco has published more than 820 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; and author of the forthcoming book, Atmospheric Chemistry by Cambridge University Press. He is a recipient of the Willard Gibbs Medal Award, the Linus Pauling Medal, and the Centenary Prize from the Royal Society of Chemistry (London). He was elected to the American Academy of Arts and Sciences, the National Academy of Sciences, the American Philosophical Society, and the German National Academy of Sciences Leopoldina. 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. He was President of the American Chemical Society in 2010. He currently serves on the Board of Directors for the American Association for the Advancement of Science.

Reservations are requested: The event is free and open to the public.