VISUALIZATION IN AN ELECTRON-MICROSCOPE OF THE IMPACT OF ENERGETIC PROJECTILES IN AMORPHOUS TARGETS

Crystalline and amorphous NI3B have been irradiated at 300 K with GeV uranium ions and with 30 MeV C-60 fullerene ions. These projectiles de posit a very large amount of energy in the targets via electronic exci tation and ionization, which results in the creation of amorphous trac ks in the crystalline compound and of 'disordered amorphous' matter ly ing in the vicinity of the projectile path in I-he initially amorphous target, which is the first state leading to the well-known anisotropi c growth of amorphous materials submitted to high electronic excitatio ns. It is shown here that it is possible to directly visualize in an e lectron microscope the impact of the ions in the amorphous targets. Th is allows us to compare the sizes of the observed impacts with those o f disordered regions that were previously extracted from phenomenologi cal models describing damage creation in amorphous matter and to compa re the extension of damaged regions induced in the same compound when bombarded in its crystalline and amorphous forms.