Time-resolved Fourier transform emission spectroscopy of A2Π-X2Σ+ infrared transition of the CN radical

The A2Π-X2Σ+Δv = −3 bands of the 12C14N radical have been observed by time-resolved Fourier transform spectroscopy in the 1850-3100 cm−1 region with a wavenumber resolution of 0.025 cm−1. The radical was produced in a pulsed positive column discharge in a cyanogene and helium mixture. Seven bands of v = 0-3, 1-4, 2-5, 3-6, 4-7, 5-8, and 6-9 were analyzed to give the molecular constants of each state by least-squares fitting of 801 lines. The pulsed discharge was found to be efficient for production of CN in the excited A2Π state. The vibrational excitation temperature was determined to be 6680 ± 835 K and 6757 ± 534 K for the A2Π and X2Σ+ states, respectively. The population of the A2Π was found to be 4% of that of the X2Σ+ state in the time after turning off the discharge.