Electronic energy loss of H3+ ion clusters in SiO2 films

A new technique based on the 151.2 keV resonance of the 18O(p,α)15N (Γ=50 eV) nuclear reaction was used to study the energy loss of H3 clusters in Si18O2 films. This approach enabled to work with target thickness from 2.5 up to 50 nm. For depths between 2.5 and 7.0 nm, the ratio R reached values between 1.8 and 2.1. The maximum effect observed with the thinnest film is R=2.1±0.4. The experimental results also show that, for thicknesses above 50 nm, H3 molecules loss energy at the same rate of a cluster of three independent protons. Results of theoretical calculations based on the dielectric formalism and using Lindhard's dielectric constant showed good agreement with the experimental results.