Heavy Ion Rutherford Backscattering Spectrometry

Abstract

Theory predicts enhanced mass and depth resolution as well as greater sensitivity for RBS with heavy ions vs. protons or alphas. In this study the actual analytical capabilities of Heavy Ion RBS (HIRBS) were evaluated for several heavy ion beams. The optics of interest were: selectivity, i.e., the mass resolution, the profiling ability, i.e., depth resolution, and sensitivity, i.e., quantitative aspects. Four heavy ion beams were employed in this work: 23.49 MeV ('16)O('2+), 23.25 MeV ('20)Ne('3+), 37.89 MeV ('40)Ar('4+), and 38.60 MeV ('84)Kr('5+). Targets of 45 to 197 amu were irradiated and observed with a silicon surface barrier detector (SSBD). A summary of experimental results follows. Selectivity. For a quantitative resolution of the stable isotopes ('63)Cu and ('65)Cu, all ion masses up to 60 amu are applicable. The qualitative resolution of the stable isotopes of ('107)Ag and ('109)Ag is feasible with these heavy ion beams. For target masses between 80 and 120 amu, the ('16)O, ('20)Ne, and ('40)Ar ions are equally applicable. For target masses above 120 amu, the ('40)Ar beam provides the best mass resolution. Profiling ability. A depth resolution of between 100 and 200 (ANGSTROM) for most elements is possible with these beams at normal incidence. At grazing incidence, a depth resolution of 10 to 20 (ANGSTROM) is feasible for most elements. ...