De-excitation rates for excited xenon molecules

The time decay of the density of excited xenon molecules $({\mathrm{Xe}}_2\mathrm{*)}$ in the lowest bound diatomic states was monitored by observing the photons (1730 ± 100 Å) emitted in transitions to the repulsive ground state. Mutual ionizing collisions of the excited diatomic states are responsible for the initial decay at high excited‐state density. The measured rate for this process is (3.5 ± 1.4) × 10⁻¹⁰ cm³ sec⁻¹. At lower excited‐state densities, the decay of ${\mathrm{Xe}}_2*$ is controlled by spontaneous emission [(20 ± 8) × 10⁶ sec⁻¹], collisional deactivation [(3,3 ± 1.3) × 10⁻¹⁸ cm²], and electronic recombination.