Materials modifications with cluster beams: Bulk and surface modifications

It is now well accepted that electronic excitation and ionization arising f rom the slowing down of swift heavy ions can lead to structural modificatio ns in some metallic targets as it has been known for a long time in insulat ors. A rapid overview of some results obtained after GeV monoatomic heavy i on irradiations will be given. It will then be shown that new specific effe cts take place during irradiations with cluster ions. The projectiles used are energetic cluster beams: 10 to 40 MeV Au-4 or C-60 ions. The rates of l inear energy deposition in electronic excitation are close for GeV monoatom ic and for 10 MeV cluster ions, but the cluster ions have characteristic ve locities which are one order of magnitude smaller than those of monoatomic ions. This leads to a strong spatial localization of the deposited energy d uring the slowing down process. The density of deposited energy can then re ach values as high as a few 100 eV/atom. This very high density of energy d eposited in the electronic system of the targets can lead to spectacular st ructural modifications: generation in the vicinity of the ion trajectories of isolated or agglomerated point defects, new crystalline phases, amorphiz ed regions...After an overview of such damage induced in bulk metals, semic onductors, and insulators, we will discuss surface damage, consisting in th e formation of bumps, craters, "lava-flows" on the target surface.