Inner-shell photodetachment fromRu−

Abstract

Inner-shell photodetachment from ${\mathrm{Ru}}^{\ensuremath{-}}$ was studied near and above the $4p$ excitation region, 29-to-91-eV photon energy range, using a merged ion-photon-beam technique. The absolute photodetachment cross sections of ${\mathrm{Ru}}^{\ensuremath{-}}$ ($[\mathrm{Kr}]4{d}^{7}5{s}^{2}$) leading to ${\mathrm{Ru}}^{+}$, ${\mathrm{Ru}}^{2+}$, and ${\mathrm{Ru}}^{3+}$ ion production were measured. In the near-threshold region, a Wigner $s$-wave law, including estimated postcollision interaction effects, locates the $4{p}_{3/2}$ detachment threshold between 40.10 and 40.27 eV. Additionally, the ${\mathrm{Ru}}^{2+}$ product spectrum provides evidence for simultaneous two-electron photodetachment (likely to the ${\mathrm{Ru}}^{+}$ $4{p}^{5}4{d}^{6}5{s}^{2}$ state) located near 49 eV. Resonance effects are observed due to interference between transitions of the $4p$ electrons to the quasibound $4{p}^{5}4{d}^{8}5{s}^{2}$ states and the $4d\ensuremath{\rightarrow}\ensuremath{\varepsilon}f$ continuum. Despite the large number of possible terms resulting from the ${\mathrm{Ru}}^{\ensuremath{-}}$ $4d$ open shell, the cross section obtained from a 51-state $\mathit{LS}$-coupled $R$-matrix calculation agrees qualitatively well with the experimental data.