Core-excited autoionizing states in the alkali metals

Abstract

An extension of projectile-electron spectroscopy to keV-energy alkali-metal beams has permitted the first observations of the energies of a number of optically forbidden core-excited autoionizing states of the alkali metals. For example, we have located the $(1s2{s}^{2})^{2}S$ and the $(1s2{p}^{2})^{2}D$ states of Li which lie at 56.31\ifmmode\pm\else\textpm\fi{}0.03 eV and 61.04\ifmmode\pm\else\textpm\fi{}0.03 eV, respectively, above the ground state. Energies for theoretically less-well-established doublet and quartet states in Na, ${\mathrm{Mg}}^{+}$, and K are also presented.