Temperature Dependence of the Onset for Negative-Ion Formation in CO2

Abstract

We have studied the formation of ${\mathrm{O}}^{-}$ ions with zero kinetic energy from C${\mathrm{O}}_2$, a reaction typical of the forms $e^{-}+XYZ\to X^{-}+YZ or \to X{Y}^{-}+Z$, where $\mathrm{XYZ}$ is a triatomic molecule. We find that the onset energy shows a marked dependence on the temperature of the gas, and we conclude that such onset measurements must be extrapolated to 0°K to give meaningful electron affinities.