Polaritonic\nBright and Dark States Collectively Affect\nthe Reactivity of a Hydrolysis Reaction

Vibrational strong coupling (VSC) has emerged as a means\nfor modifying\nchemical reactivity. Despite the intriguing discoveries and progresses\nin the field, the precise mechanisms that govern polaritonic chemistry\nstill deserve further interrogation. Herein, we use the hydrolysis\nof ammonia borane in D<sub>2</sub>O as an exemplary reaction and systematically\ninvestigate the influence of VSC on its reactivity. Experimental evidence\nof the coexistence of a resonant effect and reaction acceleration\nis observed in this system. In particular, we find that when the O–D\nstretching mode of D<sub>2</sub>O is strongly coupled to a cavity\nmode, reaction acceleration is observed. The reaction rate acceleration\nfactor, μ, is consistently observed to be dependent on the coupling\nconditions between the vibrational and cavity modes, and reaches a\nminimum at zero mode detuning, suggesting that a resonant effect is\nlikely in play. In addition, we find that μ decreases with an\nincreasing Rabi splitting. Based on these experimental findings, we\npropose that the overall influence of VSC on this reaction is likely\ndetermined collectively by the polaritonic bright and dark states.\nThese findings could help shed new light on the intricate effects\nof VSC on ground-state reaction landscapes.