Modification of ground-state chemical reactivity via light–matter coherence in infrared cavities

Abstract

Reaction-rate modifications for chemical processes due to strong coupling between reactant molecular vibrations and the cavity vacuum have been reported; however, no currently accepted mechanisms explain these observations. In this work, reaction-rate constants were extracted from evolving cavity transmission spectra, revealing resonant suppression of the intracavity reaction rate for alcoholysis of phenyl isocyanate with cyclohexanol. We observed up to an 80% suppression of the rate by tuning cavity modes to be resonant with the reactant isocyanate (NCO) stretch, the product carbonyl (CO) stretch, and cooperative reactant-solvent modes (CH). These results were interpreted using an open quantum system model that predicted resonant modifications of the vibrational distribution of reactants from canonical statistics as a result of light–matter quantum coherences, suggesting links to explore between chemistry and quantum science.

Editor’s summary

Hybrid light-matter states called polaritons, which are formed by strong interactions between resonant molecular transitions and photonic modes in microcavities, could be used to control chemical reactions with electromagnetic fields, a long-standing goal in chemistry. Unfortunately, such “polariton chemistry” still lacks a series of convincing demonstrations. Ahn et al . performed a joint experimental and theoretical study of alcoholysis of phenyl isocyanate with cyclohexanol under various strong light-matter coupling conditions. Through a rigorous analysis of their theoretical and experimental results, the authors provide compelling arguments for how cavity-altered reactivity may arise. These results are needed in this emerging field because they provide an important corroboration of earlier observations that became controversial after several reports of failed attempts. —Yury Suleymanov

Abstract

Robust experiment and modeling confirm that chemical reactions can indeed be modified under vibrational strong coupling.