Theoretical and experimental binding energies for the d7s2 4F levels in Ru-, including calculated hyperfine structure and M1 decay rates

Relativistic configuration interaction (RCI) calculations predict that the 4d75s22J=9, 7, 5 and 3 4F levels of Ru- are all bound with binding energies 1.076, 0.905, 0.795, and 0.725 eV, respectively. Using laser photodetachment threshold spectroscopy, the binding energies of the 2J=9 and 2J=7 levels are measured to be 1.04638(25) and 0.8653(10) eV, respectively, in good agreement with the calculated values. Hyperfine structure constants for all levels and magnetic dipole decay rates have also been calculated, and a systematic study of the important role of quadruple excitations is presented.