Observation of a new Cd I autoionising level by (e,2e) spectroscopy

Electron-electron coincidence spectroscopy is used to detect a previously unknown Cd I autoionising level at 12.01 eV. This is done by an analysis of the angular distribution of ejected electrons observed in coincidence with electrons scattered through a chosen angle. The new level has J>1 and, for a scattering angle of 3 degrees and 150 eV impact energy, an excitation probability one fifth that of the Cd I (4d 9 5s 2 5p) 3 P 1 12.06 eV autoionising level.