HCF(X^~1A^’) radicals were produced by laser photolysis of HCFBr₂ at 213 nm, and electronically excited from the ground state to X^~1A^”(030) at 492.70 nm with a dye laser pumped by a Nd∶YAG laser. The reaction rate constant of HCF(X^~1A^’) with SO₂ at room temperature (T＝293 K) was determined to be k＝(1.81±0.15)×10^－12 cm³•molecule^－1•s^－1, when the total pressure was 1862 Pa. Based on the high level ab initio calculations, the mechanism of this reaction was proved to be a typical addition-elimination reaction. The temperature and pressure dependences of the total reaction rate constant were calculated by applying RRKM-TST model. The calculations could provide a well consistent description for our experimental work.

Key words: HCF(X^~1A^’) radical, laser photolysis/laser induced fluorescence, reaction rate constant, pressure dependence, temperature dependence