<p>A comparative study on the optical and structural properties of nanocomposite thin films with the effect of low- and high-energy ion bombardment has been performed in this study. The fabrication of Au-C₆₀ nanocomposite thin films by incorporating nanosized Au into a fullerene C₆₀ matrix via thermal co-deposition technique has been successfully achieved. These films were irradiated by 120&#xa0;keV Ar and 150&#xa0;MeV Ag ion beam using two different low-energy and high-energy ion accelerators. The optical spectra of pristine and irradiated thin films were observed in the wavelength region from 300 to 1000&#xa0;nm, indicating a minor blue shift in wavelength at higher fluences for the low-energy ion irradiation but no significant changes in high-energy ion irradiation. This behavior of optical response by Au nanoparticles under irradiation is explained by Maxwell Garnett’s effective medium theory. The shift in SPR bands is explained with the help of induced interaction between particles due to ion irradiation. To understand the disorders and defects induced in the fullerene C₆₀ matrix due to ion irradiation, Raman Spectroscopy measurements were done before and after irradiation in case of low-energy and high-energy ion beams. The transformation of fullerene C₆₀ into amorphous carbon has been seen in both cases. XPS technique was used to extract information on element composition in Au-C₆₀ nanocomposite thin films and the change in chemical bonding before and after irradiation. The surface morphology of nanocomposite thin films investigated by AFM and FESEM technique reveals the formation of island structure-like formation with increased fluence of Au ions.</p>