Photoionization of N2O: Mechanisms of photoionization and ion dissociation

Abstract

From high resolution photoionization mass spectrometric data on normal and isotopically substituted N₂O it is concluded that the formation of NO⁺ below the à state of N₂O⁺ but above the thermochemical threshold involves the calculated but hitherto unobserved ⁴A″ state. This state decays to NO⁺ from low vibrational levels, and mainly to O⁺ from higher levels. The O⁺ ion is a more important product of N₂O photodissociation than previously thought. The B̃ state of N₂O⁺ is shown to decompose to NO⁺ and N₂⁺ and the C̃ state to NO⁺, N₂⁺, N⁺, and O⁺. The branching in autoionization from the Ã, B̃, and C̃ Rydberg series to states of different continua has been determined and is found to depend more on the type of series than on the principal quantum number. The shapes of the resonances are strikingly different in the different final channels. The relevance of these findings to ionospheric O⁺+N₂ reaction is discussed.