Vicinage effects in Rutherford backscattering intensities of MeV cluster ions penetrating thin layers of condensed matter

Abstract

The intensities of Rutherford backscattering (RBS) from thin layers of 0.5 MeV H +, 1.0 MeV H + 2 and 1.5 MeV H + 3 ion beams have been measured with different targets of C, Si, Ge, TiO 2 and Au. It is found that the RBS intensity ratios within certain critical penetration depths on H + 2 and H + incidences and on H + 3 and H + incidences are less than unity. The cluster to atomic stopping power ratio and the nuclear separation between protons in cluster ions, within which the vicinage effect continues to occur, are determined from the reduction rate in the intensity ratio and the characteristic depth. It is shown from the experimental data that the equipartition rule holds for the stopping of 0.5 MeV protons in C and Si targets and that the characteristics nuclear separation is well explained in terms of v/ ω 0, when the contribution of core electrons, lost by ionization, is involved in the frequency ω 0 of the plasmon wakes trailing individual protons.