Low pressure flame determinations of rate constants for OH(A) and CH(A) chemiluminescence

Absolute excited state concentrations of OH(A), CH(A,B), and C 2(d) were determined in three low pressure premixed methane-air flames. Two-dimensional images of chemiluminescence from these states were recorded by a filtered CCD camera, processed by Abel inversion, and calibrated against Rayleigh scattering. Using a previously validated 1-D flame model with known chemistry and excited state quenching rate constants, rate constants are extracted for the reactions CH + O 2 → OH(A) + CO and C 2H + O → CH(A,B) + CO at flame temperatures. Variations of flame emission intensities with stoichiometry agree well with model predictions.