Surface tracks by MeV C60 impacts on mica and PMMA

Muscovite mica has been bombarded by C-60 ions with energies between 2 and 15 MeV. The produced surface tracks have been analyzed by atomic force microscopy (AFM). The particle impacts formed hillocks with a height which increases with energy from 2 to 6 nm. For impacts of I, Ge-3, C-8, C-10, Cu-9, and Cu-10 MeV ions, hillocks smaller than 0.6 nm have been found. Irradiation with GeV monoatomic particles at similar energy loss performed by other research groups has only changed the frictional properties of the mica surface but did not produce any hillocks. The results can be understood qualitatively by taking into account the large difference in the velocity of the projectiles and the secondary particles along the track. PMMA irradiated with MeV C-n, Ge-n, and I ions exhibited holes with diameters between 18 and 45 nm after development. The measured track area as a function of energy loss shows an approximately linear behavior, pointing towards a diffusive spreading of energy. (C) 1998 Elsevier Science B.V. All rights reserved.