In the resonant condition, for the parallel configuration, the rate is first increased with ∆ and then saturates. But for the anti-parallel dipole configuration, the rate drops quickly with an increasing ∆. Despite the opposite trends in the parallel and anti-parallel dimer, the rate modification effect is asymmetric in the resonant condition for two dipole orientations, as shown in Fig. . Therefore, we anticipate that the rate modification resulting from the direct intermolecular dipolar interaction may not be completely averaged out in a randomly oriented ensemble.