Experimental study of the C(3P)+N(4S)+M→CN(B 2Σ+)+M recombination

The kinetics of the CN(B 2Σ+→X 2Π) violet band emission produced by the reaction of active nitrogen with cynogen (C2N2) have been studied as a function of the number densities of atomic carbon, atomic nitrogen, and total pressure. CN(B 2Σ+) in vibrational states v?7 is produced by energy transfer from a stabilized metastable CN(4Σ+) precursor CN(4Σ+)+M→CN(B 2Σ+, v?7)+M. CN(4Σ+) is formed in a three body recombination process from N and C atoms C(3P)+N(4S)+M→CN(4Σ+)+M. There is a collisional equilibrium between CN(B 2Σ+) and CN(A 2Π) at energies around 40 000 cm−1. CN(B 2Σ+) in vibrational levels v<7 is populated by energy transfer from CN(A 2Π): CN(A 2Π, v?19) +M→CN(B 2Σ+, v<7)+M. Written as a single step, the CN(B 2Σ+) formation is adequately described by C(3P)+N(4S) +M→CN(B 2Σ+)+M (1). The rate coefficient of Reaction (1) was measured absolutely and is k1= (9.4±2.5) ×10−33 cm6 molecule−2⋅sec−1 (M=argon).