Abstract
α-quartz has been irradiated with heavy ions: , , and at an energy of about 1 MeV/amu in order to cover a range of electronic stopping powers dE/dx between 2.4 and 9 keV/nm and , , , , , and between 1 and 5.8 MeV/amu for dE/dx>7 keV/nm. The extent of the induced damage is determined using Rutherford backscattering ion channeling with a 2-MeV beam. The damage cross section A is obtained using a Poisson law =1-exp(-Aφt), where φ is the flux and t the irradiation time. This damage cross section is linked to the effective radius through the relation A=π, where is the radius of an equivalent cylinder of damage. Using high-resolution electron microscopy, cylinders of amorphous matter have been observed, whose radius corresponds to when the track is continuous (i.e., for A≥1.3× ; ≥2 nm). A thermal-spike model is applied to calculate the radii of the observed tracks assuming that the observed amorphous cylinders correspond to a rapid quench of a molten liquid phase along the ion path. The model is applied only when the latent track is continuous and cylindrical. A good agreement is obtained taking into account that the initial spatial energy deposition on the electrons depends on the ion velocity.
- Received 1 November 1993
DOI:https://doi.org/10.1103/PhysRevB.49.12457
©1994 American Physical Society