! 180 fs and then becomes smaller. When driving at the upper/lower polaritonic frequencies the propagation is different from the central frequency excitation. To better quantify this behavior, we calculate the running time integral of the probability flux and use the linear regression to extract the corresponding slope and intercept. Their ratio corresponds to the average rise time. Results of these calculations are shown in Fig. for molecules in and out of the resonant cavity. By this measure, it is seen the dissociative dynamics is significantly slowed down when the driving frequency is resonant with either lower or upper polaritons.