Signature of plasmon excitations in the stopping ratio of fast hydrogen clusters

Abstract

In the present work, we have explored the interference effects which arise when H2 + and H3 + cluster ions interact with a thin layer of SiO2 in order to obtain a clear signature of plasmon excitations induced by these energetic projectiles. For this purpose, high-energy-resolution experiments were carried out as a function of the incoming projectile energy, covering an energy range between 40 and 200 keV/amu. The ratio Rn between the energy loss of the cluster and the sum of the energy loss of its constituents has a steep increase between 70 and 100 keV/amu for both cluster ions, which is associated with the plasmon excitation threshold.