Measurement of non-Rutherford cross sections of 4He ions on 14N 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 14N was measured using 4He 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 14N 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