Symmetry of negative ions of polar molecules

The spin and space symmetry of negative ions of polar molecules are studied. It was previously known that a dipole moment exceeding 1·625 debye is a sufficient condition for the existence of the corresponding ion. It is shown that such an ion has the same space symmetry in its electronic wavefunction as does the neutral molecule. Additional negative ion states of one or more other symmetries exist if the molecule has a symmetry axis or plane, and has a dipole moment exceeding 9·638 debye. The above results are proven in the approximation that the nuclei are held stationary.