Direct investigations of the kinetics of the reactions of CN radicals with N atoms and 3CH2 radicals with NO

The kinetics of two elementary reactions of radicals important in fuel nitrogen chemistry were investigated by means of the laser photolysis -laser induced fluorescence and molecular beam mass spectrometry methods. Reaction (-1) CN+N=C+N₂ was investigated at 900 Pa total pressure. The rate constants decreased by one order of magnitude between room temperature and 534 K and could be fitted with the following Arrhenius expression: k_-1(294 K≤T≤534 K)=10^{(11.29±0.06)}exp((1770±170)/T) cm³mol^-1 At 750 K an upper limit of 5·10¹¹ cm³mol^-1 was determined for reaction (-1). In the reaction of ³CH₂ radicals with NO the addition complex CH₂NO as well as the final products OH and HCN were detected and the branching ratios (α) for the following channels have been determined: CH₂+NO→(CH₂NO)^* (CH₂NO)^*(+M)→NCO+H₂ α_{300-1025 K}<0.15 →HCN+OH α_{300 K}=0.015±0.08; α_{1025 K}=0.63±0.25 →CN+H₂O α_{300-1025 K}<0.1 By monitoring the OH formation, rate constants between 294 and 1025 K were derived: k_2a(294K≤T≤1025 K)=10^{(12.54±0.05)}exp((190±10)/T)cm³mol^-1s^-1.