Intracavity laser absorption spectroscopy measurements of CN using red system A–X. Simultaneous observation of CN, NH2, HNO and 1CH2 in low pressure hydrocarbon flames doped with nitrogen oxides

Absorption spectra of the CN radical have been measured by Intracavity Laser Absorption Spectroscopy in hydrocarbon flames doped with minor amount of nitrogen oxide. Spectra of the CN red band system (A2Π←X2Σ+) have been observed in the spectral range of 642 nm along with lines of other species from flame: NH2, HNO, 1CH2, and NO2. The sensitivity of about 2.3×1010 cm−3 at 1700 or ∼100 ppb at 30 Torr at 1700 K has been demonstrated.