The Weichman Lab develops new spectroscopic tools to elucidate the structures, dynamics, and chemical interactions of complex molecules and strongly interacting light-matter systems.

Catalysis and quantum control of reactions via strong light-matter coupling

Most key chemical problems hinge on the transformation of molecular material into desired products or useful energy. There is an ongoing need for novel, broadly applicable tools to better manipulate reaction efficiency and specificity. Polaritons – hybrid states arising through strong light-matter interactions typically engineered inside optical microcavities – have great prospects for rationally steering reaction trajectories and photochemistry. Polaritons inherit delocalization and coherence from their photonic contribution while maintaining molecular structure, interactions, and reactivity. This interplay between the local dynamics and collective phenomena of an ensemble of molecules in dialog with a common field of light is a powerful sandbox for new chemistry. However, a poor understanding of the underpinnings of cavity-altered reactivity has thus far precluded its application to genuine synthetic problems. The Weichman Lab is working to directly track the dynamics of strongly-coupled condensed-phase chemical reactions, with aims to interrogate detailed polariton reaction mechanisms and inform prospects for cavity catalysis in increasingly complex systems.

Quantum state resolved dynamics in cold nanoscale molecules

 A rigorous understanding of structure and dynamics in pristine, isolated, and typically small molecular systems has been made possible through high resolution spectroscopy. This information is essential to develop a complete understanding of many-body quantum mechanics, benchmark state-of-the-art theoretical methods, and build libraries of molecular fingerprints. Achieving a similarly detailed picture of molecules of transitional size, on the brink of treatment with our current toolkit, is an important frontier in modern physical chemistry. This goal is met with intrinsic challenges that can be overcome with novel spectroscopic and cold molecule techniques. We use cavity-enhanced frequency comb spectroscopy and buffer gas cooling techniques to fully resolve individual rovibrational quantum states in unprecedentedly complex  molecular systems. This work will bridge our understanding of small molecules with that of emergent phenomena in extended materials, and will facilitate future research avenues in laboratory astrophysics, aerosol science, and quantum information.