Generation of N3 in the thermal decomposition of NaN3

Abstract

Gaseous azide radicals at concentrations up to 10¹³ molecules cm⁻³ appear to have been generated in a flow system in the thermal decomposition of solid NaN₃ at temperatures between 150 and 350 °C. Between 150 and 250 °C the activation energy for the decomposition is 0.80±0.15 eV. The addition of small concentrations of oxygen atoms to the reactor excites NO γ‐band chemiluminescence from the reaction O+N₃^k4→NO (A ²Σ⁺)+N₂. The γ‐band emission may be used as a sensitive tracer for N₃ in kinetic measurements; k₄ was determined to be (10±4) ×10⁻¹² cm³ molecule⁻¹ s⁻¹. Large concentrations of O atoms quantitatively convert the N₃ to NO, and the resulting O/NO afterglow has been used to determine absolute concentrations of the N₃ radicals. Several other chemiluminescent emissions are observed, most notably the nitrogen first‐positive emission excited in azide‐radical recombination.