Fig. 1.

Interaction of helium ions with nanoporous AAO. a Shows the principles of the experimental setup. Helium ions with keV energy are generated in a gas field ion source and then are scanned over the sample in a high vacuum chamber. Secondary electrons that are generated by the sample are used for in situ monitoring of the ion-beam interactions with <1 nm resolution. The studied samples are thin films of nanoporous membranes of aluminum oxide (either supported by a substrate or locally stand free in vacuum). b, c Symbolic illustration of observed phenomena: the microscopic response of the matter to irradiation is determined by the interplay between the nature of the chemical bonds, ionization effects, and irradiation-induced diffusion