Photochemical decomposition of gaseous hydrogen azide

Abstract

The photochemical decomposition of HN₃ has been investigated at room temperature (25 ± 3°C) and with 2139 Å radiation. The decomposition leads to NH and N₂, both of which are also vibrationally excited and are capable of causing further decomposition of HN₃. The vibrational energy of both NH′ and N′₂, but not the electronic energy of NH, are removed by collision with CO₂. The hydrocarbons (i-C₄H₁₀ and C₂H₆) also deactivate N′₂ and remove NH′ by chemical reactions. The detailed mechanism is discussed and ratios of relevant rate constant derived. It has been shown that (a) occurs to the extent of (95–97 %), while (b) occurs to the extent of (5-3 %) :HN₃+hv(λ= 2139 Å)→NH′+ N′₂, (a), HN₃+hv→H + N₃(b).