The theoretical and experimental distinguishing of photoassociation into the XeCl(B) state

The spectrum of excitation into the XeCl(B) state is simulated by a procedure rigorously taking into account the bound-bound (bb) and free-bound (fb) transition contributions. The cross-sections for bb-absorption and photoassociation are calculated, and at their maxima, near λ = 308 nm, they amount to 1.2 × 10−16 cm2 and 1.4 × 10−38 cm5, respectively. An experimental approach is developed enabling the distinguishing of fb-transition contributions by monitoring the excitation into the XeCl(B) state in conditions when the equilibrium between nonexcited XeCl(X) molecules and free Xe and Cl atoms does not have time to be completed. The experimentally obtained ratio of intensities for the bb- and fb-transitions, amounting to 1.8–3.3, is in good agreement with the calculations. These experiments enabled estimation of the rate constant for XeCl(X) state dissociation in bimolecular collisions with Xe atoms as being (3–6) × 10−11 cm3 s−1.