16. Structural Transformations in Fullerene C₇₀ Thin Film by 65 MeV Ni Ion Beam Irradiation

Under swift heavy ion irradiation at different fluences, the structural transformations of fullerene C₇₀ thin film prepared by thermal evaporation are investigated. Fullerene C₇₀ thin films are irradiated with 65 MeV Ni ions beam at different fluences from 1 × 10¹² to 1 × 10¹⁴ ions/cm². The impact of energetic ions on the fullerene molecule leads to the extinction of C₇₀ molecule. In order to study the stability of fullerene C₇₀ under ion irradiation, damage cross section and ion track radius of damaged cylindrical zones are determined using fullerene C₇₀ vibration modes and their change at different fluences as recorded by Raman spectroscopy. Damage cross section is found to be 1.01 × 10⁻¹³ cm², and ion track radius of damaged cylindrical zone is found to 1.8 nm. Fullerene C₇₀ is completely converted from crystalline structure to amorphous carbon at a fluence of 1 × 10¹⁴ ions/cm².