Thermal decomposition of nitrogen trifluoride in shock waves

Abstract

The thermal decomposition of nitrogen trifluoride has been reinvestigated behind incident shock waves in dilute (1%) NF3/Ar mixtures over the temperature range 1150–1530 K and at 0.80–1.81 atm total pressures. The reaction kinetics were followed by monitoring NF2 radical concentrations in absorption at 260 nm. In several experiments, the infrared emission at 5.17 μ was also monitored. Under the experimental conditions used, the reversible dissociation NF3+M?NF2+F+M is known to be first order in both NF3 and Ar concentrations, and the low pressure limit second-order rate constant was found to be k1(cm3 mol−1 s−1) =1016.61±0.13 ×exp[−(48.0±0.8 kcal mol−1)/RT] using an approximate iterative procedure. A numerical solution of the differential rate equation yielded comparable results. The temperature dependence of the absorption coefficient for NF2 and the equilibrium constant were also determined.