Abstract: The measurements of quenching rate constants of CH(A,B) radicals by (CH₃)₂NH, (C₂H₅)₂NH, (C₂H₅)₃N, n-C₅H₁₂, n-C₆H₁₄ and n-C₇H₁₆ are presented by using laser photolysis of CHBr₃ at 266 nm and time-resolved fluorescence quenching technique.It is found that the quenching rate constants for both Aand Bstates increase almost linearly with increasing C-Hnumber contained in the alkane molecule.But for larger alkane molecules, it appears that the quenching rate increase is smaller than that for small alkane molecules.The formation cross sections of complexes between electronically excited CHand amine and alkane molecules were calculated by using collision complex model.It is found that the dependence of the formation cross section of complex on the number of C-Hbonds in the alkane molecules is in good agreement with that of the measured quenching cross section.This implies that the attractive forces between CH (Aand B) and alkane molecules are probably important in collisional quenching processes of CH (Aand B) by alkane molecules.The similar conclusion could be drawn for quenching of CH(Aand B) by amine molecules.

Key words: CH radical, Amine molecule, Alkane molecule, Quenching