An analysis of the temporal emission of broadband tunable excimer lasers such as Xe
2Cl shows that the laser pulse can be described in terms of a

-switch model rather than by steady-state considerations. For electron-beam (

-beam) pumped rare gas halide mixtures, transient absorption of the majority gas-usually argon-acts as a chemical

-switch. The ring-up time of the delayed laser pulse may be conveniently used for optimization of the laser gas mixture.