15min:

SERGEY CHESKIS, IGOR DERZY, School of Chemistry, Tel Aviv University, Tel Aviv 69978, Israel; VLADIMIR A. LOZOVSKY, Semenov Institute of Chemical Phisics, Russian Academy of Sciences, 4 Kosygina str., 117977 Moscow, Russia.

Intracavity Laser Absorption Spectroscopy (ICLAS) and Cavity Ring-Down Spectroscopy (CRDS) were used to detect absorption spectra of CH(C^{2 +} X² ) at 314 nm, ¹CH₂ (b¹B₁ a¹A₁) at 590 and 620 nm, NH (A³ _i X^{3 -}) at 336 nm , and NH₂ (A²A₁ X²B₁) at 598 nm in a low-pressure (30 Torr) stoichiometric methane/oxygen/nitrogen flat flame doped with a small amount of nitrous oxide . The CH and NH radicals were monitored by CRDS whereas ¹CH₂ and NH₂ were monitored by ICLAS. The absolute concentration profiles of those radicals were measured. The radical absorption spectra were recorded with good signal-to-noise ratio. The spectra of the ¹CH₂ radical were measured in different spectral ranges that allowed us better determination of its absorption cross section. For the first time the absolute concentrations of NH and NH₂ were measured in the flames of this kind. The agreement between experimental results and model predictions based on the GRI-Mech 2.11 mechanism is discussed.