Two mega-electron volt proton-irradiation effects on fullerene films

Abstract

Polycrystalline fullerene (C₆₀) films prepared on hydrogen-passivated Si(1 1 1) substrates were irradiated by 2 MeV protons with fluences ranging from 6×10¹⁵ to 1×10¹⁷ ions/cm². Ferromagnetic-like ordering is reported for samples irradiated with a fluence of 6×10¹⁵ ions/cm² [S. Mathew et al., arxive:cond-mat/0503315]. Raman spectroscopy results indicate an enhancement of the characteristic A_g and H_g modes of C₆₀ after irradiation, especially for the fluence 6×10¹⁵ ions/cm². High-resolution transmission electron microscopy and transmission electron diffraction results show the crystalline nature of both as-deposited and irradiated films in the fcc structure. Stability of the fullerite structure under the above irradiation condition is discussed.

Keywords:

• Fullerene and related materials
• Irradiation effects
• Raman spectroscopy

Acknowledgements

We thank Prof. S.N. Behera for his important suggestions and encouragement throughout the course of this work.