SOFT-X-RAY LASING TO THE GROUND-STATES IN LOW-CHARGED OXYGEN IONS

Optimal schemes for the creation of a transient population inversion b etween the ground and excited states of an ion in a subpicosecond-puls e laser-produced plasma are discussed. First results on experimental i nvestigations of possible amplification in the soft-x-ray spectral reg ion on transitions to the ground states in O II, O III, C III, and N I II ions are reported. Ions are produced due to optical field ionizatio n of O-2, CO2, and N-2 gases in an intense Ti:sapphire laser field. Am plification on the 2p3s(P-3)-2p(2)(P-3) transition (lambda = 374.12 An gstrom) in O III ions and on the 2p(2)3s(P-2)-2p(3)(D-2) transition (l ambda = 616.56 Angstrom) in O II ions has been observed.