This analysis also provides a possible explanation for the resonance effect at normal incidence (𝑘 ‖ = 0) for a 1D FP cavity. In Eq. 23, it is clear that the peak of this function is located at 𝜔 c = 𝜔 0 for 𝑘 ‖ = 0. Thus, the VSC-modified rate constant occurs only when 𝜔 c = 𝜔 0 . This is because there is a van-Hove-type singularity in the 1D DOS, 𝑔 1D (𝜔 k ), which manifests itself as the 1/