Stopping Power for Fast Nitrogen and Oxygen Diclusters in Carbon

Measurements of stopping powers for several diatomic ions are presented and compared to values derived from well known wake models. While independently determined wake forces can be superposed to calculate correctly the stopping forces on light fast ions, such as H2+, the method appears to be invalid for slower, more highly charged N2+ ions. To include non-linear terms in the interaction wake charge distributions must be determined for pairs of ionic cores. To avoid the complexities of a proper quantum mechanical treatment a semi-classical calculation of free electron scattering by two screened ionic cores was used to determine the stopping forces. While a quantum mechanical calculation is needed to obtain a definitive result the semi-classical calculation provides qualitative agreement with experiment for 3 MeV N2+ ions in carbon.