Gain spectra of a long-pulse XeCl laser, measured in the range 307.5–308.8 nm with a resolution of 1 cm-1

The gain spectrum of a long-pulse ( ~ 0.5 μs) XeCl laser was investigated in a master oscillator—single-pass amplifier configuration. One Fabry–Perot etalon with a free spectral range ~200 cm^-1 and a finesse F = 30 was used to tune the frequency of the XeCl master oscillator. This made it possible to generate frequency-tunable radiation with a linewidth ~1 cm^-1 and to record, with approximately the same precision, the gain spectrum of the XeCl laser in the range 307.5–308.8 nm. The time dependence of the small-signal gain of the active medium of the XeCl laser was investigated, with a resolution of ~10 ns, for the 0–2 transition in the XeCl molecule.