Velocity dependence of electronic excitation transfer reactions: (CO*,N2*,Kr*)+Hg(6 1S) → (CO,N2,Kr)+Hg(6 3P1)

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Abstract
The velocity dependences of the sensitized fluorescence of mercury by metastable CO(a 3Π, N2(A 3Σ+u), and Kr(5 3P2,0) were determined using crossed molecular beams with the metastable beams time‐of‐flight velocity selected. With CO(a) and N2(A) excitation is directly to Hg(6 3P1), whereas with Kr(3P) higher triplet states of mercury are also excited. The collisional energy ranges studied with CO, N2, and Kr were 32–516, 30–468, and 31–394 meV, respectively. The cross section collisional velocity dependence was found to be quite similar for the three systems, with a negative v−n velocity dependence in the low velocity region becoming neutral or positive at higher velocities. The values of n were 0.750±0.014 for CO(a) + Hg up to 242 meV, 1.009±0.016 for N2(A) + Hg up to 202 meV, and 0.810±0.024 for Kr(3P) + Hg up to 140 meV. The results are compared with velocity dependences of other nonadiabatic reactions, and discussed in terms of electronic coupling vs curve crossing theories for such processes.