Professor Joseph Francisco

Izaak M. Kolthoff Lectureship in Chemistry
Professor Joseph Francisco
Department of  Chemistry and Department of Earth and Environmental Science
University of Pennsylvania
Host: Professor Don Truhlar


A Fresh Look at the Chemistry Behind Acid Rain

The two major components of acid rain are sulfuric acid (H2SO4) and nitric acid (HNO3). Sulfur dioxide (SO2) is the main precursor of H2SO4.  Atmospheric sulfur dioxide is oxidized homogeneously by reaction of SO2 with OH and O2 leading to SO3, which then reacts with water to form sulfuric acid. This is the now accepted acid rain mechanism for generation of atmospheric sulfuric acid. In this talk we will review the traditional acid rain mechanism and we will introduce a new acid rain mechanism that relies on the photochemistry of SO2  and show how this new chemistry can be an important ingredient in the overall mechanism of acid rain formation not yet considered by current atmospheric models.

Sulfur dioxide has been proposed in solar geoengineering as a precursor of H2SO4 aerosol, a cooling agent active in the stratosphere to contrast climate change due to the anthropogenic emissions of greenhouse carbon dioxide. Considering the introduction of SO2 in the stratosphere, the photochemistry of HOSO is critical to understanding the role of SO2 mitigating climate change. The spectroscopy and photochemistry this new species provide important insights that help to better understand SO2 chemistry in earth's upper atmosphere.


Professor Joseph S. Francisco’s laboratory focuses on basic studies in spectroscopy, kinetics, and photochemistry of novel transient species in the gas phase. He has made significant contributions in many areas of atmospheric chemistry by applying new tools from experimental physical and theoretical chemistry to atmospheric chemical problems. His research has transformed our understanding of chemical processes in the atmosphere at the molecular level. Francisco’s work has led to important discoveries of new chemistries occurring on the interfaces of cloud surfaces as well as fundamental new types of chemical bonding that control these processes.

Professor Joseph S. Francisco

Francisco 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 700 journal articles, written several book chapters, and he is the co-author of the fundamental textbook in chemical kinetics and dynamics, Chemical Kinetics and Dynamics. He is a recipient of the Alexander von Humboldt U.S. Senior Scientist Award, the EdwardW. Morley Medal from the Cleveland Section of the American Chemical Society, and a John Simon Guggenheim Fellowship. Francisco is a Fellow of the American Chemical Society, the American Physical Society, the American Association for the Advancement of Science, and the American Academy of Arts and Sciences. He is also a Member of the National Academy of Sciences, the American Philosophical Society, and the German National Academy of Sciences Leopoldina.

Francisco is currently the 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. From 2005-07 he served as President of the National Organization for the Professional Advancement of Black Chemists and Chemical Engineers and was President of the American Chemical Society in 2010. Also in 2010, Francisco was appointed to the President’s Committee on the National Medal of Science by President Barack Obama.


Start date
Thursday, Sept. 30, 2021, 4 p.m.
End date
Thursday, Sept. 30, 2021, 5 p.m.

This seminar will be presented remotely and live-streamed
Location To Be Determined
Zoom Link