Surface Tracks and Cratering in Polymers

Abstract

A surface track may be defined as the portion of the surface of a material that is modified or perturbed in response to the energy deposited by an individual ion (or a cluster) penetrating a solid. Three main features are often distinguished in a surface track: a region of lattice disorder, a hole or crater, and a region of raised material with dimensions of the order of nanometers. In certain materials only bumps are seen at the impact sites, and in others, on the contrary, only rimless craters are present. Cratering by single ions has been observed in different materials for projectiles in a broad range of energies, from less than a keV to many GeV. Here we concentrate on summarizing the data on polymers and biopolymers for track-forming ions (i.e. ions in the electronic stopping regime). Surface tracks on other materials (see [1] for a review) will not be treated here, except for comparison purposes. The reader is also referred to the literature on cratering in the nuclear-stopping regime [2–9], but so far most of it, if not all, is for nonpolymeric targets.