Chemical Reactions of C_n⁺（n=3, 4, 5） with O₂ in an RF Ion Trap

C_n⁺ （n=3, 4, 5） cluster ions have been produced and stored in our RF ion trap by method of laser ablation Furthermore, by means of the advantage of mass selective storage and long storage time of ion trap, we have developed the study of chemical reactions of C_n⁺ cluster ions with O₂ in the ion trap Chemical reaction rate constants of reactants and branching ration of products have been discussed through the results from the endothermicity and exdothermicity of these reaction processes.