Role of Energy Loss-Range Profile of Heavy Ions in Tailoring the Optical Properties of Polycarbonate

Polycarbonate (PC) samples have been implanted with 115 keV N+, Ar+ and Kr+ at fluences ranging from 5x10(14) to 1x10(16) ions/cm(2) to be employed for optical studies. A Decrease in optical energy gap, enhancement in reflectivity and reduction in transmittance, particularly in UV-region, is observed for all implanted samples. The change in optical properties of PC, first, by keeping energy deposited/cm(2) constant (i.e. keeping energy*fluence constant) and then by keeping same depth of penetration for different ions have been analysed in detail. The changes are found to be more prominent for N+ compared to Ar+ and Kr+ when the fluence/energy deposited/cm(2) by the ions is same. Further, the energy for N+ is reduced to 46 keV, while for Kr+ it is increased to 200 keV to ensure the same penetration depth for N+, Ar+ and Kr+ in PC. Finally, the results are explained on the basis of energy loss-range profiles of these ions in polycarbonate and through Raman spectroscopy. This study convincingly demonstrates that not only the types of ion species, their energies and fluences, but the total energy deposited by ions and their depth of penetration also plays an important role in tailoring the optical properties of polymeric materials.