Enhancing Infrared-Laser Dissociation of Molecules with the Electromagnetic Vacuum

Controlling bond breaking is a long-standing goal in molecular physics. Infrared nanocavities are currently being developed for reaching exotic coupling regimes of cavity QED with a few molecules, but it is not well understood how chemical reactions would proceed in such systems. We study infrared laser photodissociation of a single molecule that strongly interacts with a resonant infrared vacuum, subject to a strong laser field that either resonantly drives the molecule or injects photons into the cavity. We show that the intensities required for photodissociation are significantly lower inside the cavity than in free space. By directly injecting photons into the cavity, the molecule dissociates with 2 orders of magnitude less laser energy than by directly driving the vibrational mode. This photodissociation enhancement is a purely quantum mechanical effect that cannot be captured semiclassically. Our Letter provides fundamental mechanistic understanding of chemical dynamics that can be used for designing new types of nanophotonics experiments that probe single-molecule chemistry.