Generation of N3 in the thermal decomposition of NaN3

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+N3k4→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.