Abstract: On a flowing afterglow apparatus, the quenching of SO(c¹Σ^－) by SO₂, O₂, CO₂, N₂, He, CS₂, CH₃OH, C₂H₅OH, C₃H₇OH, C₄H₉OH, CH₃COCH₃, C₆H₆, CH₂Cl₂, CH₂Br₂, CHCl₃, or CCl₄ was studied firstly and successfully. The quenching rate constants of SO(c¹Σ^－) by them were measured. By analysis, it demonstrates that the quenching rate constants of SO(c¹Σ^－) by the alkanol molecules, C_nH_2n+1OH(n=1, 2, 3, 4), are semi-proportional to the number of C—H bond in them; the quenching by the non-polar small molecules, such as CO₂ and N₂ is not efficient; while it is obvious by SO₂ because of its strong polarity. The size and volume of halogen atoms in the halomethane molecules play an important role in quenching SO(c¹Σ^－), and it seems that there is no evident correlation between the quenching rate constants and the number of the chlorine atom in the chlomethane molecules.

Key words: SO(c¹Σ^－), Quenching rate constant, Alkanol molecules, Collisional complex, Dynamics