Electron emission from Ne9+ interacting with thin SiO2 films

The secondary electrons emitted during the interaction of highly charged ions with solid surfaces carry detailed information about the complex interaction mechanism. In the past, the study of the secondary electrons emitted from the interaction with metal surfaces revealed the fascinating dynamics of the hol-low atoms formed above and below the surface. However, in the case of the interaction with insulating surfaces there is still some controversy whether the relaxation dynamics is the same as for metals. In addition, the microscopic and macroscopic charging of the insulating surfaces, which constitutes an im-portant part of the interaction mechanisms, makes these studies difficult.
Here, we report on the emission of electrons from Ne9+ interacting with thin SiO2 films. The typical LMM and KLL Auger electrons resulting from the last steps in the neutralisation process are observed on top of a broad secondary electron background. The mean peak positions of the Auger electrons are shifted to lower energies compared to the Auger electrons from metal sur-faces. Two mechanisms will be discussed for the interpretation of this obser-vation: the macroscopic charging of the SiO2 surface and a weaker screening of the ions in the SiO2 film.