Experimental electronic stopping cross-section of EUROFER97 for slow protons, deuterons and helium ions

The experimental electronic stopping cross-section of EUROFER97 for slow protons, deuterons and helium ions is deduced from backscattering experiments from ultrathin film stacks redeposited by magnetron sputtering from bulk EUROFER97 and tungsten on silicon substrates as well as bulk EUROFER97 using Time-of-Flight Low-Energy Ion Scattering (ToF-LEIS). Two different experimental approaches were employed. In absolute measurements, the energy of ions backscattered from the W layer in spectra recorded for the ultrathin film stacks was compared to the signal from bulk W under the same experimental conditions. In relative measurements, the intensity of the spectra from bulk EUROFER97 and a Cu reference sample using the same experimental conditions were compared. In both approaches, the energy-converted spectra were compared to Monte-Carlo simulations for quantitative analysis and to account for the contributions of multiple and plural scattering. The deduced electronic stopping cross-sections of EUROFER97 are compared to predictions by SRIM using Bragg's rule of stopping power additivity and recently combined RT-TDDFT and MD simulations for protons in bulk Fe in the off-channeling geometry. The differences between the results from the two approaches are discussed.