Resonantly enhanced, three-photon ionization of Xe: Optically pumped rare-gas laser

Three-photon ionization of xenon, resonantly enhanced by the Xe6p[1/2]₀ state at 80 119 cm^-1, is observed when a xenon atom simultaneously absorbs one ArF (51733-cm^-1) and two XeF (28 482-cm^-1) photons. For ArF and XeF laser intensities in the 1-100-MW cm^-2 range, the peak electron density is more than an order-of-magnitude larger than that obtainable by the nonresonant, two-photon ionization of Xe by ArF. The spontaneous radiative lifetime of the 6p[1/2]₀ level and the rate constant for quenching of the state by background Xe atoms were measured to be 29±{}4 ns and 4±{}1 ×{} 10^-10 cm³{s}^{{-}1}$, respectively. Excitation of the $6p{[1/2]}₀$ state is both selective and intense and has resulted in lasing on the $6p{[1/2]}₀{→}6s{[3/2]}₁$ transition at 828.0 nm, which represents the first optically pumped rare-gas laser.