Physical/Analytical Seminar: "Exploring photocatalytic mechanisms via ultrafast time-resolved spectroscopy"

Presenter: 

Laura Sawyer   

Chemistry & Biochemistry Department, The University of Arizona

Hosted by: Dr. Vanessa Huxter

Abstract: Photoredox catalysis has found widespread application in green chemistry, drug discovery and the production of industrially relevant chemicals. The field of photocatalysis includes a wide range of potential activation pathways in which the absorption of light brings the catalyst into an excited state to drive the catalytic process. Light-driven reactions offer the advantage of employing less reactive/low-energy reagents, unveiling previously elusive or unknown mechanistic pathways and positively influencing industrial production. Indirect methods, such as redox potential measurements, bond dissociation energies and spectroelectrochemistry, fall short in revealing comprehensive information about intermediates involved in catalytic processes. Optical ultrafast time-resolved techniques can be used to track processes central to photoredox catalysis, such as charge transfer, intersystem crossing, and internal conversion. Using steady-state measurements, LED exposure, time correlated single photon counting and transient absorption spectroscopy, we can map the mechanisms of various molecules. The following seminar will discuss Tripyrrindione complexes synthesized by the Tomat Lab and the commercially available xanthene dye Rhodamine 6G. 

Bio: Laura Sawyer is a 6^th PhD Candidate in the College of Optical Sciences. As a member of the Huxter Group, Laura’s research focuses on using advanced optical spectroscopy techniques to explore the fundamental mechanisms of photoredox catalysis, specifically exploring the proposed excited state radical mechanism of Rhodamine 6G. Laura previously received her Bachelor's in Electrical and Computer Engineering at Western New England University in Springfield, Massachusetts in May 2020. Her accomplishments during her graduate studies includes Outstanding Teaching Assistant (May 2022), Eli Lilly Travel Award recipient (August 2024) and Outstanding Graduate Student (May 2025).