Time-resolved CH (A^2Δ and B^2∑^−) laser-induced fluorescence in low pressure hydrocarbon flames

Abstract

Total collisional removal rate constants for the CH A(2)Delta and B(2)Sigma(-) electronic states are obtained in low pressure (<20-Torr) hydrocarbon flames. The B state is consistently removed ~70% faster than the A state. Variations of +/-50% are observed for different rotational levels and positions in the flame. For these flames, A-state emission following excitation of the B state indicates a rapid electronic-to-electronic energy transfer pathway that is insensitive to collision environment. Upper limits to the collider specific cross sections are obtained for H(2)O, N(2), and CO(2). The CH concentration and temperature profiles are measured and parametrized using a unique method.