High-resolution ejected-electron spectrum of magnesium autoionising levels following two-electron excitation by low-energy electron impact

The ejected-electron spectrum of magnesium vapour following autoionisation of two-electron excited states of the type 1s 2 2s 2 2p 6 3pnl is presented for the first time. Ejected electrons were energy analysed at 75 degrees to the direction of an incident electron beam of energy 17 to 500 eV. 46 lines are reported in the ejected-electron energy range 0.5 eV to 4.5 eV, of which 40 have been assigned to eight series. Comparisons are made with ultraviolet observations and theoretical calculations.