Sputtering of the refractory cores of interstellar grains

Abstract

Sputtering yields are calculated for the release of Si and O from amorphous SiO2 and of C from amorphous carbon, under impact of 4He+, 12C+, 16O+, 28Si+ and 56Fe+ ions, for energies in the range 40 ≤ E ≤ 500 eV. The yields are derived using the TRIM code, which simulates the results of the transport of ions in matter by means of classical Monte Carlo techniques. The probability of ejection of an atom is computed at a given energy, for a number of angles of incidence, and then integrated to obtain the mean yield at that energy. These numerical results are then fitted by a simple function of energy for convenience in subsequent applications; the parameters of these fits are tabulated. Illustrative C-shock calculations show that sputtering of charged grains by heavy neutral species dominates at low shock velocities. © 1997 RAS.