Laser Excitation and Ionization in a Dense Li Vapor: Observation of the Even-Parity, Core-Excited Autoionizing States

Abstract

The first optical absorption from excited states to autoionizing core-excited levels has been observed in lithium. A 1-MW dye laser tuned to the $1s^{2}2s\to 1s^{2}2p$ resonance produced ∼${10}^{16}$ excited atoms/${\mathrm{cm}}^2$ in a heat-pipe oven. Far-uv absorption spectra of ${\mathrm{Li}}^{*}\mathrm{}\left(2p\right)\mathrm{}$ and ${\mathrm{Li}}^{+}$ were obtained. A curve of the evolution from excited neutrals to ∼95% ions is presented, and the significance of the Li observations for understanding the ionization mechanism is discussed.