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^-2ṡsec^-1 (M=argon).