Doubly excited states of ammonia in the vacuum ultraviolet range

The cross sections for the emission of dispersed fluorescences in the ultraviolet and visible ranges by excited hydrogen atoms and NH radicals in the photoexcitation of ammonia have been obtained as a function of incident photon energy in the range of 13-40 eV, in which five superexcited states have been found. Three of these states around 22, 30 and 33 eV are doubly excited states, which have been investigated in detail for the first time and the others are single-hole one-electron superexcited states around 15 and 26 eV. It is remarkable that the doubly excited states around 30 eV give as large oscillator strengths for Balmer fluorescences as the nearby single-hole one-electron superexcited states around 26 eV that are built on the (2a(1))(-1) ion core, which seems not to be amenable to the independent electron model.