Experimental study of the reactions of N2(A 3Σ+u) with CH3CN and HCN: The effect of vibrational energy in N2(A)

The rate constants and product channels have been determined for the reactions of N2 (A 3Σ+u, v=0–3) with CH3CN and HCN. The discharge–flow technique was employed, with LIF (laser induced fluorescence) detection of N2(A,v) and CN(X,v′) and resonance fluorescence detection of H atoms. For N2(A,v)+HCN, the rate constant increases from (5.8±0.9)×10−12 cm3 s−1 for v=0 to (3.1±0.5)×10−11 cm3 s−1 for v=3, and for N2(A,v)+CH3CN, the rate constant increases from (1.3±0.2)×10−11 (v=0) to (6.0±0.9)×10−11 cm3 s−1 (v=4). A large dependence of the product channels on v is also observed. While cleavage of the C–H bond is the principal channel for reaction of N2 (A, v=0) with both reagents, dissociation of CH3CN to CH3+CN is the major channel for reaction of N2 (A, v>2). The data are discussed in terms of initial attack of N2(A) at the CN bond of the reagent, followed by vibrational energy redistribution within the molecule.