Damage of ion irradiated C-60 films

Thin C-60 films deposited on clean silicon substrates were ion irradiated a nd subsequently investigated by using the Raman spectroscopy technique. The C-60 films were bombarded with He, N and Bi ions at energies from 30 to 80 0 keV and fluences in the range 10(11)less than or equal to phi less than o r equal to 10(16) ions cm(-2). Our results reveal that both, the nuclear (S -n) and the electronic (S-e) energy transfers destroy the C-60 molecules. I n addition it is shown that there is a well established relationship betwee n the total energy density transfer phi(S-n + S-e) and the amount of destro yed C-60 molecules. The damage process of the C-60 starts when the total tr ansferred energy density reaches the value required to release one atomic b ond of C-60, and the destruction is completed at a transferred energy great er than or equal to 0.5 eV A(-3), which corresponds to the energy density o f the C-60 molecule. (C) 1999 Elsevier Science B.V. All rights reserved.