The energy spectrum of negative ions in condensed matter

The mobilities of negative ions in nonpolar dielectric liquids are discussed by taking into account the structure of the liquid around the ions. It is found that the exchange repulsive interaction between the lone electron of the negative ion and the electron shells of the atoms or molecules comprising the liquid can reduce significantly the effect of electrostriction which leads to the formation of a solid-like shell around a positive ion. It allows to explain the difference in mobilities of positive and negative ions in dielectric liquids. Estimations are made for the negative ion of the oxygen molecule in gaseous He and Ne, and liquefied Xe. The influence of the surface barrier on the electron energy spectrum of a negative ion localized on the surface of dielectrics is investigated. Increase of the potential barrier results in a decrease of the electron binding energy and it can lead to detachment of the electron. Estimations are made for the negative ion of the oxygen molecule placed on the surface of solid Ar, Kr, and Xe. With increasing distance front the surface the image force becomes more important and it determines the shift of the electron binding energy of the negative ion.