Kinetic mechanisms in nitrogen-chlorine radical systems. Part 1.—The formation and detection of the NCl2 and N3 free radicals using time-resolved absorption spectrophotometry

Abstract

The ultra-violet, infra-red and mass spectra of gaseous NCl₃, N₃Cl and N₃Br are reported. The use of an ultra-violet absorption spectrophotometric system for the measurement of small optical densities in a low-pressure discharge-flow apparatus is described. The radicals NCl₂(from the reaction Cl + NCl₃) and N₃(from the reaction Cl + N₃Cl) were detected by means of their ultra-violet absorption spectra, using this system. The rate of removal of NCl₂ radicals at 298 K and from 1–3 torr total pressure was second-order in [NCl₂] and independent of total pressure, and a mean value for the second-order rate constant, k₂=(5.5 ± 0.4)× 10¹¹ cm³ mol^–1 s^–1, was found under these conditions.