Inner-shell photoexcitation in an open-shell atom: The Cl2p→ns,mdspectrum as a case study

The $2\overrightarrow{p}ns,md$ excitation spectrum has been measured and calculated for the open-shell Cl atom. A satisfactory accord between experiment and theory was found. Rydberg series cannot be discerned for transitions leading to a $2p,$ $3p,$ $n\mathcal{l}$ open-shell configuration. The $4s,3d$ manifolds are dominant, and the $2p-3p$ coupling is seen to be much stronger than the $3p-n\mathcal{l}$ coupling. Very narrow widths, 16 to 22 meV, for the $4s$ and $3d$ lines are observed. By contrast, only broad structures appear in the region of the highest excitations.