Energy deposition process density

The defects generated in ion—soHd interactions influence the kinetic processes that occur both inside and outside the cascade volume. At times long after the cascade lifetime (t > 10 s), the remaining vacancy—interstitial pairs can contribute to atomic diffusion processes. This process, commonly called radiation enhanced diffusion (RED), can be described by rate equations and an analytical approach (27). Within the cascade itself, under conditions of high defect densities, local energy depositions exceed 1 eV/atom and local kinetic processes can be described on the basis of ahquid-like diffusion formalism (28,29). 

DEPTH PROFILE. The secondary electrons produced by ionization processes from an incident beam of high-energy electrons are randomly directed in space. Spatial "equilibrium" is achieved only after a minimum distance from the surface of a polymer in contact with a vacuum or gaseous environment (of much lower density). Consequently, the absorbed radiation dose increases to a maximum at a distance from the surface (2 mm for 1 MeV electrons) which depends on the energy of the electrons. The energy deposition then decreases towards zero at a limiting penetration depth. 

During irradiation by swift ions, latent ion tracks are formed along the path of the ions. After irradiation, the material is subjected to chemical treatment leading to formation of the hollow channel from the latent ion track. The size and shape of the etched ion track is determined by the chemical processing. The etch process depends on the energy deposition density of the ion along its path, on the radiation... 

The sp -character of ta-C is strongly correlated with high mass density, which is achieved by a deposition process in which the atoms or clusters of atoms that form the film have high kinetic energy [51,52]. This favors the formation of sp -bonding which is characteristic of diamond. Although the diamond structure is relatively empty (only 34% of its volume can be filled by hard spheres) diamond C nonetheless has the highest known number density of atoms. 

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