THEORY OF NEGATIVE-ION DECAY IN AN EXTERNAL ELECTRIC-FIELD

A theory of the decay of a weakly bound negative ion in an external electric field taking into account the long-range polarization interaction between the escaping electron and the atomic residue is developed. The calculations are performed for the Rb- and Ca- ions. It is shown that the asymptotic theory of the negative ion decay which neglects the polarizability of the atomic core will strongly underestimate the decay probability and polarizability of negative ions. Our results for Ca- are important for the correct interpretation of recent observations of the Ca- decay in an external electric field. It is shown that the experimental results for the decay probability are more consistent with the electron affinity of 21 meV rather than 17.5 meV obtained in the experimental paper. However, the new value of the electron affinity is still much lower than the results of most accurate theoretical calculations.