Collisions of electrons with interstellar grains

We have computed cross-sections for elastic and inelastic scattering of electrons on small grains at low-collision energies. Significant differences are again found between the results obtained in the presence and the absence of a ‘permanent’ grain dipole moment. In addition to spherical grains, scattering on ellipsoidal grains is investigated. We conclude that the rate of electron attachment to interstellar grains may be substantially lower in regions of molecular clouds from which the radiation field is excluded, and where the grains are less likely to possess a dipole moment.