Abstract: Using laser induced fluorescence technique and shifting the position of the burner, two-dimensional concentration distribution diagrams of C_2(X) and CH(X) radicals in a part premixed, rich LPG/air flame were first obtained. The excita- tion and the detection bands were (0, 0) and (0, 1) of C_2(A~(3Π)←→X~(3Π)) transitions respectively, while for CH(X) species, the transition of B~(2∑), v′=0←X~(2Π), v″=0 was excited and the followed process A~(2Δ), v′=0→X~(2Π), v″=0 was detec- ted.
Both C_2(X) and CH(X) radicals concentrated in the thin layer of the inner cone of the flame and in an ellipsoid beyond the cone. C_2 was generated via pyrolysis and then agglomerated to form carbon particles. CH was produced from the reaction of small hydrocarbon radicals with oxygen and/or oxides in flame.