Ion irradiation hardening of C-60 thin films

The nanoindentation technique is used to measure the hardness and the Young 's modulus of ion irradiated C-60 films, 70 nm thick, deposited on a Silico n substrate. An increase of hardness from 1.3 GPa for the pristine sample t o 10 GPa after irradiation with 800 keV Bi+ and N2+ ions was observed. The Young's modulus also increases from 60-150 GPa after the irradiation. The r esults are discussed in terms of the damage and amorphization produced as c onsequences of the electronic and nuclear energy transference due to the ir radiation. (C) 1999 Elsevier Science S.A. All rights reserved.