Collision-induced luminescence from the impact of ions and cluster ions on solid rare gases

Light emission during the collision of ions and cluster ions on a metal surface covered by rare gas matrices of variable thickness is reported. The light intensity as a function of distance from the metal surface follows the classical image dipole theory. The spectral signature of the light corresponds to the fluorescence of the neutral cluster species deposited as well as to fragments. The nature of the processes involved in this luminescence, in the neutralization and the excitation are discussed. A microscopic model for the mechanism is proposed: in this model rare gas excitons are produced in the collision process.