Negative ions in the gas phase

TABLE 4.4 Electron Affinities of Atoms, Molecules, and Radicals Electron affinity of an atom (molecule or radical) is defined as the energy difference between the lowest (ground) state of the neutral and the lowest state of the corresponding negative ion in the gas phase. A(g) + e = A-(g) Data are limited to those negative ions which, by virtue of their positive electron affinity, are stable. Uncertainty in the final data figures is given in parentheses. Calculated values are enclosed in brackets. ... 

Kiser, R. W. Doubly-Charged Negative Ions in the Gas Phase. 85, 89-158 (1979). 

Electron affinity of an atom (molecule or radical) is defined as the energy difference between the lowest (ground) state of the neutral and the lowest state of the corresponding negative ion in the gas phase. 

A dozen years ago experimental evidence for the existence of doubly-charged negative ions in the gas phase was first reported by Stuckey and Kiser Subsequent observations and reports by other investigators have confirmed the existence of these novel ions. It has been established that these unique species can have lifetimes of the order of 0.1 ms or longer. Still, little is known of the mechanisms of formation and of the properties of these doubly-charged negative ions. 

A sin e mechanism can now be proposed for the formation of doublynegative ions in the gas phase. This mechanism is consistent with all experimental facts provided to the present, and is as follows. 

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