Interaction of Highly Charged Ions with the Surface of Insulators

The interaction of highly charged ions (HCIs) with surfaces has been the subject of in-tense scientific research in the last years. Special attention was paid to the interaction with the surface of metals, where the formation of hollow atoms and their relaxation dynamics has been studied in detail [1]. From theses studies the interaction scenario for metal surfaces has been revealed and found to be consistent with the classical-over-barrier-model [2]. In contrast, the study of the interaction of HCIs with insulating surfaces is not as complete and still lacks some understanding [3].
The main differences between metals and insulators can be found in the higher work function, the lower density of electrons in the conduction band, and the much lower conduc-tivity. Therefore, the microscopic and macroscopic charging of insulating surfaces, which constitutes an important part of the interaction mechanisms, makes these studies difficult. Different methods can be used to overcome this difficulty. Using thin layers of a deposited material is one of the possibilities and will be presented here for the interaction of highly charged Ne ions with the SiO2 surface. Secondary electron emission from these layers and the calorimetric determination of the potential energy retention in these layers will be compared to results on Au surfaces.
In addition, the main aspects of the interaction of HCIs with insulating surfaces will be reviewed briefly. By means of the emission of x-rays and secondary electrons the formation and relaxation of hollow atoms above insulating surfaces will be discussed. Furthermore, the more applicative aspects of the interaction of HCIs with insulators like potential sputtering and single ion induced surface tracks and modifications will be covered.