Soft-x-ray lasing to the ground states in low-charged oxygen ions

Abstract

Optimal schemes for the creation of a transient population inversion between the ground and excited states of an ion in a subpicosecond-pulse laser-produced plasma are discussed. First results on experimental investigations of possible amplification in the soft-x-ray spectral region on transitions to the gorund states in O ii, O iii, C iii, and N iii ions are reported. Ions are produced due to optical field ionization of ${\mathrm{O}}_{2}$, ${\mathrm{CO}}_{2}$, and ${\mathrm{N}}_{2}$ gases in an intense Ti:sapphire laser field. Amplificaiton on the 2p3s${(}^{3}$P)-2${\mathit{p}}^{2}$${(}^{3}$P) transition (\ensuremath{\lambda}=374.12 \AA{}) in O iii ions and on the 2${\mathit{p}}^{2}$3s${(}^{2}$P)-2${\mathit{p}}^{3}$${(}^{2}$D) transition (\ensuremath{\lambda}=616.56 \AA{}) in O ii ions has been observed.