Gas phase atomic association reactions of Ar+, Kr+, and Xe+ at temperatures near 1 K

We report the measurement of gas phase three-body atomic ion–atom association reaction rate coefficients at temperatures near 1 K using a free jet flow reactor. The association rate coefficients for the reactions of Ar+ with Ar and Ne, Kr+ with Kr and Ar, and the reactions of Xe+ with Xe, Kr, and Ar have been measured. In all these cases except Ar++Ne, the rate at 1 K is in excess of 9×10−29 cm3/s and a strong negative temperature dependence is observed. These observations are discussed with respect to several microscopic descriptions of the association process.