The Phase Effect in Electronic Stopping: A Survey of the Contributing Physical Processes

The phase effect in electronic stopping deals with the question whether the energy loss of an ion due to the interaction with electrons depends on the state of aggregation of the target. It is commonly accepted that charge changing collisions of the projectile and changes in the electronic states of the target contribute to the phase effect In addition, the energy loss measurements might possibly be influenced by different impact parameter selection in the two experiments (solid and gas phase). Quantitative results of our calculations show that generally the impact parameter selection inherently present in a transmission experiment is quenched by the inevitable multiple scattering of the projectiles. Thus, electronic excitation and ionization in the projectile and the target are the only processes that contribute significantly to the phase effect