Electron Capture by Polar Molecules

It is shown that binding of electrons in the electric dipole field of polar molecules cannot possibly occur, if the molecules have an electric dipole moment smaller than the critical value $D_0=1.63\mathrm{}\times {10}^{-18\mathrm{}}$ esu cm, irrespective of the size of the dipole. This result casts doubts on a proposed mechanism of electron scattering by polar molecules, namely, electron capture with rotational excitation of the molecule.