NCN quantitative measurement in a laminar low pressure flame

摘要: Abstract The present work has been performed to quantitatively determine the NCN radical concentration profile in a laminar low-pressure CH 4 /O 2 /N ( ϕ  = 1.25) flame. Laser induced fluorescence (LIF) technique implemented order record spectrum 326.7–330.1 nm range flame conditions, and secondly measure spatially resolved by exciting main congested branch of around 329.13 nm. LIF calibrated into absorbance using cavity ring-down spectroscopy (CRDS). calibration absolute done PGOPHER spectral simulation program. experimental simulated spectra were found be very good agreement. It allowed reconsidering exact assignment transitions involved strong bandhead at temperature, which actually originate from contribution both origin (0 0 0) band (0 1 0Σ + ) component (0 1 0) contrary ambient temperature where only is significant Thanks electronic transition dipole moments extracted available lifetimes, we provide direct determination absorption cross-section: σ λ  = 329.13 nm) = (9.4 ± 1.8) × 10 −17  cm /molecule 1830 K. This cross-section was constant within ±15% 1500–1900 K range. Its important for research groups concerned with chemistry high prompt-NO formation. From that peak mole fraction determined equal 170 ± 90 ppb uncertainty mainly linked CRDS measurement conditions close detection limit should reduced yielding higher concentration.