Laser-induced fluorescence of CN(X2 Σ+) produced by photolysis of C2N2 at 160 nm

Laser-induced fluorescence has been used to investigate the energy partitioning into the electronic, vibrational, rotational, and translational degrees of freedom of CN radicals produced in the photolysis of cyanogen (C2N2) at λ=160 nm (7.75 eV, 62 500 cm−1). The CN radicals that were produced in the (X2 Σ+) state were found to be vibrationally and rotationally excited. The initial distributions of the rotational line intensities of the (0,0) and (1,1) bands in the violet (B2 Σ+↔X2 Σ+) band system are characterized by Boltzmann distributions in which Trot (0,0) ∼1400 K and Trot(1,1) ∼1100 K. The observed Boltzmann character of the rotational state distributions is explained by a type II predissociation, which produces statistically randomized energy distributions in the fragments. It is observed that approximately 95% of the vibrational energy in CN(X2 Σ+) appears in the v″=0 and v″=1 levels. Evidence is presented which shows that C2N2 predissociates to produce equal amounts of CN(A2 Πi) and CN(X2 Σ+).