title: NCO quantitative measurement in premixed low pressure flames by combining LIF and CRDS techniques.
abstract: NCO is a short-lived species involved in NO(x) formation. It has never been quantitatively measured in flame conditions. In the present study, laser-induced fluorescence (LIF) and cavity ring-down spectroscopy (CRDS) were combined to measure NCO radical concentrations in premixed low-pressure flames (p = 5.3 kPa). NCO LIF excitation spectrum and absorption spectrum (using CRDS) measured in a stoichiometric CH(4)/O(2)/N(2)O/N(2) flame were found in good agreement with a simulated spectrum using PGOPHER program that was used to calculate the high-temperature absorption cross section of NCO in the A(2)Σ(+)-X(2)Π transition around 440.479 nm. The relative NCO-LIF profiles were measured in stoichiometric CH(4)/O(2)/N(2)O/N(2) flames where the ratio N(2)O/O(2) was progressively decreased from 0.50 to 0.01 and in rich CH(4)/O(2)/N(2) premixed flames. Then, the LIF profiles were converted into NCO mole fraction profiles from the absorption measurements using CRDS in a N(2)O-doped flame.
authors.affiliation: Laboratoire PC2A, UMR8522 CNRS/ Université Lille1, Cité Scientifique, 59655 Villeneuve d'Ascq, France. nathalie.lamoureux@univ-lille1.fr
authors.forename: Nathalie
authors.initials: N
authors.lastname: Lamoureux
authors.forename: Xavier
authors.initials: X
authors.lastname: Mercier
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Pauwels
authors.forename: Pascale
authors.initials: P
authors.lastname: Desgroux