Vibrational predissociation of the Ar⋅⋅⋅Cl2 van der Waals complex: The small molecule limit for intramolecular vibrational redistribution

A converged three‐dimensional quantum treatment of vibrational predissociation in the Ar⋅⋅⋅Cl2(B3Π0u+,υ′) van der Waals complex is presented. The potential energy surface used is a sum of pairwise Morse atom–atom interactions adjusted asymptotically to a C6/R6+C8/R8 anisotropic van der Waals form. Calculations have been performed in the energy region of Ar⋅⋅⋅Cl2(B,υ’=6, 10, and 11) excited levels. In agreement with the experimental findings, the final rotational distribution of Cl2 is found to be strongly dependent on the initial υ’ state being excited, as well as on the number of vibrational quanta lost in the vibrational predissociation process. The role of intramolecular vibrational redistribution for υ’=10 and 11 for which the Δυ=−1 channel is closed is also studied. It is found that the vibrational predissociation (VP) dynamics are dominated by the coupling of the zero‐order ‘‘bright’’ state with a single ‘‘dark’’ state from the υ’−1 manifold of van der Waals vibrationally excited states which then d...