Measurement of non-Rutherford cross sections of exp 4 He ions on exp 14 N at a laboratory backscattering angle of 171 deg between 7.5 and 9.8 MeV

The ratio of the non-Rutherford to the Rutherford cross section of exp 14 N was measured using exp 4 He ions in the energy range between 7.5 and 9.8 MeV at a laboratory backscattering angle of 171 deg in order to complete the data published by Foster et al. (Nucl. Instr. and Meth. B 79 (1993) 454), who measured the ratio at a lower backscattering angle of 167 deg . This is important because of the interest in using high energy helium ion backscattering to determine the nitrogen content in heavy substrates. Non-Rutherford backscattering spectra and exp 14 N depth profiles of nitrogen-implanted titanium alloys, that serve as an application of the new cross sections, are shown in this work as well. The measurements were done at beam energies of 7.5--8.2 MeV and from 9 to 9.8 MeV. Results show a resonance around 9.3 MeV with cross sections that are about 100 times higher than the values for Rutherford backscattering. Copyright (c) 2002 Elsevier Science B.V.