Cavity-Modified Unimolecular Dissociation Reactions via Intramolecular Vibrational Energy Redistribution

Molecules coupled to infrared cavities in resonance with certain vibrations have demonstrated altered optical and chemical properties, revealing a path toward enhanced reaction selectivity and energy transport. However, the microscopic mechanism governing these modulated properties is not yet well understood. Several theories have been proposed, but so far, explaining each of the observed features of vibrational polariton chemistry remains a challenge. Here, we explore how the intramolecular vibrational energy redistribution can be modified inside a cavity, in turn affecting the rate of unimolecular dissociation. We study a classical model of a triatomic molecule, where the two outer atoms are bound by anharmonic Morse potentials to the center atom. We show how energy-dependent anharmonic resonances emerge and that resonantly coupling the optical cavity to particular dynamical resonance traps can either significantly slow down or increase the intramolecular vibrational energy redistribution processes depending on the strength of vibrational momentum-momentum mode coupling, leading to altered unimolecular dissociation reaction rates. Finally, we show that these results can be explained by studying energy transfer between the molecule and the cavity. These results lay the foundation for further theoretical and experimental work in cavity-modified intramolecular vibrational energy redistribution toward understanding the intriguing experimental results of vibrational polariton chemistry.