Vacuum ultraviolet excitation of XeCl2 van der Waals complexes and small clusters

The vacuum ultraviolet (≈ 166 nm) excitation of XeCl2 van der Waals complexes or clusters induces a charge transfer reaction leading to the formation of the XeCl∗ exciplex. A selectivity on the final product is observed, the XeCl (B 2Σ12 state being almost exclusively populated when exciting the 1-1 complexes, whereas the XeCl (C 2Π32) state appears only when larger clusters are present in the expansion. An orbital symmetry effect in the excited state of the complex may account for this selectivity. Comparison with the two-photon excitation at the same total energy has been performed.