The reaction of cyanogen radicals with nitric oxide

Vibrational energy transfer and a chemical reaction between nitric oxide and the cyanogen radical have been studied by flash photolysing cyanogen and cyanogen bromide in the presence of nitric oxide. The product of the chemical reaction is, at least in part, the unstable compound nitrosyl cyanide NOCN and the rate constant is 2 x 1012 ml. mole-1 s-1 or 1 x 1017 ml. mole-2 s-1 with nitrogen as third body. The compound has a continuous absorption in the ultra-violet and yields vibrationally excited nitric oxide on photolysis. Vibrationally excited cyanogen radicals produced by means of electronic excitation of the radical produce vibrational excitation of the nitric oxide through near resonance energy exchange. Vibrational equilibrium is reached by nitric oxide through further resonance exchanges: CN + NO → NOCN, NOCN + hv → N O (v > 0) + CN, NO (v = 0) + CN (v = n) → NO (v = 1) + CN (v = n – 1 ) , NO (v = 1) + CN (v = m) → NO (v = 2) + CN (v = m –1 ), 2NO {v = 1) ⇌ NO (v = 2) + NO (v = 0), NO (v = 2) +NO (v = 1) ⇌ NO (v = 3) + NO {v = 0), etc.