Recent experiments in polariton photochemistry have demonstrated some promising results of using moleculecavity coupling to change photochemical reactivity. One of the first experiments to demonstrate a change of photochemical reactivity in the strong coupling regime is shown in Fig. , adapted from Ref. 3. In this work, the rates of a photo-isomerization reaction (panel (i) between spiropyran and mecrocyanine via a photoexcited ring cleavage) were modified by resonant coupling between the molecules to a Fabry-Pérot cavity, with a reported Rabi splitting of Ω R = 700 meV. In Fig. ii), the proposed mechanism of this modification 3 was an increase in the decay rate of the pathway (1) (radiative relaxation from the lower polariton state) relative to the pathway (2) (excited state isomerization) caused by the formation of the lower polariton. This mechanism led to the slowdown of the isomerization reaction inside the cavity at resonance (Fig. -(iv)) but was not present in the off-resonant case (Fig. ).