Ion emission from insulators during impact of accelerated dust particles and comparison with other techniques

Dust particles of 0.2 to 20 μn size are accelerated to velocities between 1 (large particles) and 60 km/s (small particles). Ion emission from insulator-covered metal films bombarded with these particles is discussed. The mass spectra generated by this method and the excitation functions are compared with those of other techniques, namely keV and MeV-sputtering and laser-irradiation. There are certain regimes of energy deposition in each case, where similar desorption phenomena occur, such as the emission of larger intact molecules. A quantum-mechanically diabatic theory is adopted for these far-from-equilibrium surface-gas phase transitions. However, with energy depositions of higher density and area, the released species may form a collision plasma leading to far different ion types and energies due to near-to-equilibrium plasma interactions.