Stopping powers for 20–140 keV H + and He + on Ni, Ag and Au

Abstract

The stopping powers for 20–140 keV H + and He + ions in Ni, Ag and Au have been measured using the backscattering technique. Targets were thin layers (10–20 nm) of the metal of interest deposited on Si substrates. In some cases the metal layer was overlaid with a thin Au layer (10–20 nm). These two layer samples were used to establish the accuracy with which stopping power measurement could be made in the underlying material with the aim that this technique could later be used to make measurements in reactive (i.e. easily oxidized) metals. The layer thicknesses were determined using Rutherford backscattering with 1 MeV He + ions and a well calibrated detector geometry. Suitable corrections were applied for electronic screening. The energy loss of the keV ions was determined using an electrostatic analyser after correcting for the energy dependent neutral particle component in the backscattered beam. This correction factor was determined in situ in the scattering chamber and on the targets as used in the stopping power measurements; i.e. with the same surface condition. The stopping powers obtained are compared to other published data.