Critical velocities for the nanostructure creation on a metal surface by an impact of slow highly charged Arq+, Krq+, and Xeq+ ions

We study the interaction of highly charged ions (Ar q + , Kr q + , and Xe q + , charge q ≫ 1 ) with metal surfaces for low to moderate ionic velocities. We calculate the neutralization energy and the deposited kinetic energy, both necessary for the nanostructure (hillocks or craters) creation. The cascade neutralization above the surface we analyze within the framework of the time-symmetrized two-state vector model and the micro-staircase model. The energy deposition inside the solid (nuclear stopping power) we consider using the charge dependent ion-target atom interaction potential. We define the critical ionic velocities as a measure of the interplay of the neutralization energy and the deposited kinetic energy in the process of the surface modification. These quantities enable us to distinguish the velocity regions characteristic for the particular nanostructure shapes. Graphical abstract