Abstract
Electronic energy loss of light ions transmitted through nanometer films of Al has been studied at very low ion velocities. For hydrogen, the electronic stopping power is found to be perfectly proportional to velocity, as expected for a free electron gas. For He, the same is anticipated, but shows a transition between two distinct regimes, in both of which is velocity proportional—however, with remarkably different slopes. This finding can be explained as a consequence of charge exchange in close encounters between He and Al atoms, which represents an additional energy loss channel.
- Received 28 April 2011
DOI:https://doi.org/10.1103/PhysRevLett.107.163201
© 2011 American Physical Society