Short-Wavelength Lasers Pumped by Selective Auger Decay.

This dissertation discusses some of the theoretical and experimental aspects of the design of lasers in the extreme ultraviolet (XUV). XUV laser systems are limited by the short lifetime of the upper laser level and by the large energy needed to pump them. Additionally, the upper level often decays extremely rapidly by autoionization. We have constructed a 20 Joule Nd:YAG/Glass laser system to allow us to pump long lengths of lasing medium with the x-rays emitted from a laser-produced plasma. This allows us to rapidly pump levels lying far above the ground state of the atom. These highly excited levels may then undergo rapid Auger decay to the second ion of the species of interest. We have experimentally investigated systems in which the Auger decay occurs selectively to a small subset of the possible final levels. These final levels are inverted with respect to lower dying unpopulated levels. We then measure the resulting optical gain. We have examined a system in Xe III that lases at 108.9nm and have optimized the gain as a function of Xe pressure, pump pulse length, and energy. We have also measured gain on three transitions in Zn III at 127.0 nm, 130.6 nm, and 131.9 nm and optimized these gains as a function of Zn pressure. The Zn system is the first example of a laser pumped by super Coster-Kronig decay. We have also studied a system in Kr III that is analogous to that in Xe III and have measured gain at 90.7 nm. Finally, we have examined a system in Cs III at 63.8 nm. We have not seen evidence of gain but believe that large populations are being created and that under different conditions gain may occur. Appendices discuss other aspects of the physics of XUV lasers including the application of quasimetastable states to XUV laser systems and the spectroscopy of the highly excited quartet states of neutral sodium.