Magnetically induced anions

Abstract

The main focus of this review is on magnetically induced anions. Before discussing these new anionic states which exclusively exist in the presence of magnetic fields, we review in some detail the anionic physics without external field. For completeness, we also outline the properties of field-free existing anions when exposed to magnetic fields. The magnetically induced states constitute an infinite manifold assuming that the nucleus of the anion is infinitely heavy. At laboratory field strengths the corresponding binding energies show two different scaling properties belonging to the ground ($\propto B^2$) and the excited ($\propto B^3$) magnetically induced states. We provide a detailed discussion of the physics of the moving anion taking into account the coupling between the anionic centre of mass and its electronic degrees of freedom. A number of field-adapted techniques exploiting exact constants of motion and the adiabatic separation of motions are applied to simplify the Hamiltonian that describes the effective interaction between the centre of mass and the electronic degrees of freedom. Employing classical simulations the autodetachment process of the anions in the field is observed and a rich variety of spectral properties of moving anions is predicted: depending on the parameters, such as the mass and polarizability of the neutral system as well as the field strength, induced bound states, resonances and detaching states of the corresponding anions are to be expected. An outline of an {\it{ab initio}} quantum approach is provided that allows quantum dynamical investigations of the moving anion.