Impact of the experimental approach on the observed electronic energy loss for light keV ions in thin self-supporting films

Energy spectra of keV ions interacting with self-supporting foils of Au and W were recorded with a Time-of-Flight Medium-Energy Ion Scattering system in different backscattering and transmission geometries in an otherwise identical experimental setup. For He ions transmitted through Au spectra of de...
Ausführliche Beschreibung

Energy spectra of keV ions interacting with self-supporting foils of Au and W were recorded with a Time-of-Flight Medium-Energy Ion Scattering system in different backscattering and transmission geometries in an otherwise identical experimental setup. For He ions transmitted through Au spectra of detected particles depending on geometry show two distinct components, i.e. different energy loss distributions in the film, whereas for protons no such phenomenon was observed. The two components in the spectrum of transmitted He could be attributed to impact parameter dependent energy loss, being more prominent for He than for protons. The main origin of the necessary impact parameter selection along different trajectories is expected to be texture in the Au-foils. Electronic stopping powers obtained from both, most probable energy loss in transmission and best fits to spectrum width in backscattering are in agreement within experimental uncertainties. This observation applied for all investigated combinations of projectile and target material. Ausführliche Beschreibung