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Poly(ethylene terephtalate) (PET) and poly(ethylene naphthalate) (PEN) samples (0.125 mm of thickness) are irradiated with a
150 keV Mg+ ion beam at fluences ranging from 1 × 1014 up to 1 × 1016 cm−2
. Destruction of numerous bonds within both poly-
mers, increasing progressively with fluence, is confirmed via Raman and Fourier-transform infrared spectroscopy measurements.
Raman spectroscopy demonstrates the emergence of graphite-like structures—both the G and D bands, the fingerprints of such
structures, appear in the spectra for heavily modified samples. Further analysis of the absorbance spectra confirms the formation
of carbon clusters containing up to 1600 and 1300 carbon atoms for PET and PEN, respectively, which transform into vast
conducting networks in the subsurface layer. The ID /IG ratio near 0.6 suggests that the carbon structures consist of both chains and
rings. The optical bandgap is reduced from 3.85 and 3.15 eV (pristine PET and PEN, respectively) to 0.85 and 0.95 eV for the most
irradiated samples, values typical of semiconductors. The results suggest that PEN is slightly more radiation-resistant than PET.
Nevertheless, the changes in surface resistivity for both polymers due to ion bombardment are very similar; their resistivity is
reduced by more than five orders of magnitude for the most heavily processed samples.
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