Reaction rates of NH 2-radicals with NO, NO 2, C 2H 2, C 2H 4 and other hydrocarbons

Abstract

Absolute rate constants for gas phase reactions of NH2 radicals with nitrogen dioxide, nitric oxide, acetylene and ethylene have been determined in a discharge flow system with laser-induced resonance fluorescence detection of NH2. The radicals were produced by the fast reaction F+NH3. The kinetic measurements were performed in the temperature range 209≤T≤505 K at pressures of one torr He as the main carrier gas. The following rate constants were obtained: k N O 2 + N H 2 ( T ) = 1.9 ⋅ 10 20 ⋅ T − 3.0 [ c m 3 / mol sec ] k NO + N H 2 ( T ) = 2.7 ⋅ 10 17 ⋅ T − 1.85 [ c m 3 / mol sec ] k C 2 H 2 + N H 2 ( T ) = 1.42 ⋅ 10 16 ⋅ T − 2.7 [ c m 3 / mol sec ] The rate constant for the reaction of C2H4 with NH2 shows little temperature dependence kC2H4+NH2(T)=1.3·109 [cm3/mol sec]. The reactions of NH2 with allene and propylene are slow. The measurements lead to the upper limits kC3H4+NH2≤5·108 [cm3/mol sec] and kC3H6+NH2≤6·108 [cm3/mol sec] at room temperature.