Abstract
Anomalies in the yield of ion-induced secondary electrons from single-crystalline target are studied. They are (1) disappearance ofchannelling dips in the angular distribution of the yield of secondary electrons in MeV light ion channelling, and (2) an increase of the yield at angle of incidence on a surface smaller than about 10°. These are interpreted in terms of ion trajectories affected by crystal periodicity and effective mean escape length for secondary electrons in a solid.