Greg Engel Professor of Chemistry and Molecular Engineering

Research in the Engel Group focuses on excited state reactivity including excitonic transport, non-radiative relaxation to photochemical products, and new methods to image excited state dynamics. Excited states in the condensed phase have an extremely high chemical potential thereby making them highly reactive and difficult to control. Our control strategy involves exploiting coherent response of the environment to the excitation event. In particular, we develop methodologies to manipulate two fundamental components of excited state dynamics: exciton migration and non-radiative relaxation.

Our approach is inspired by biological systems optimized by evolution to exploit manifestly quantum mechanical phenomena to drive coherent energy transfer, to steer trajectories through conical intersections and to protect long-lived quantum coherence. Currently, we are focusing on four key scientific efforts: (1) new techniques to image excited state dynamics, (2) understanding mechanisms of quantum transport in photosynthesis, (3) dynamics of conical intersections in the condensed phase, and (4) engineering quantum dynamics in new classes of synthetic materials.

The Engel Group program explores the interface between biology and quantum mechanics by creating new tools to explore design principles of coherent processes in proteins. Photosynthetic light harvesting and photoenzymatic dynamics exploit coherent protein motions for chemical control in a way that we do not yet fully understand. For example, Photosynthetic antenna complexes operate with near perfect quantum efficiency and steer excitonic motion with exquisite precision. These complexes exploit both incoherent (Förster) energy transfer along with coherent (wavelike) motion of energy in a process called Environmentally Assisted Quantum Transport that offers quantum efficiency superior to either mechanism alone. The Engel group seeks to isolate and copy the microscopic details of this process. In particular, we want to know if the process is a result of evolutionary fine-tuning and, regardless, how we can enable coherent energy transfer in synthetic systems for light harvesting, sensing, and communications.

To probe these systems, we design new femtosecond spectrometers to observe how electronic states couple to one another much the way COSY NMR explores nuclear spin coupling. Exploiting this analogy, we recently developed the first optical analog to MRI for rapid detection electronic couplings. The Engel group is strongly interdisciplinary; graduate students matriculate through Chemistry and the Biophysical Sciences while postdoctoral scholars have PhDs in Chemistry or Physics. The group contains pure theorists, organic chemists, inorganic chemists, physical chemists, physicists, and biophysicists. Engel and his lab members collaborate with physicists, biologists, engineers, and corporate partners to develop new technologies and new science.