The Spectra of Sc IV, Ti V, Mn VIII and Fe IX in the Isoelectronic Sequence A I to Fe IX

The successful excitation of scandium in a vacuum hot spark has enabled the completion of the spectroscopic data in the isoelectronic sequence A I to Fe IX and has led to the identification of radiation connecting the higher terms with the ground state (${}_{}{}^1{}_{}{}^{}S_0^{}{}_{}{}^{}$) in all ions up to and including Fe IX.