Coulomb repulsion of lattice ions under swift heavy ion irradiation

When swift heavy ions (SHI) move through a solid, they interact with the nuclei and electrons of the atoms. If the projectile velocity exceeds the Bohr velocity, the main process is the excitation of the electron subsystem, i.e. excitation and ionization of the target atoms. Due to their kinetic energy, the excited electrons leave the region near the SHI trajectory. The electrical neutrality of the lattice is violated, and the positive charge of the ions can lead to damage of the lattice structure (Coulomb explosion). It is shown that the trajectory of an excited electron has a turning point providing very short repulsion time of positively charged ions. Due to the large inertia of the lattice ions, the atomic displacement during this time is much less than the lattice constant. No Coulomb explosion is possible due to Such displacements. (c) 2005 Elsevier B.V. All rights reserved.