Browsing by Author "Kumar, Shyam"

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    Argon ion implanted CR-39 polymer: Optical and structural characterization
    (Elsevier B.V., 2021-04-03T00:00:00) Chhokkar, Preeti; Kumar, V.; Goyal, Parveen K.; Kumar, Shyam; Tomar, A.K.; Gaur, Anurag; Arya, Anil
    The samples of Polyallyl diglycol Carbonate (CR-39) were implanted with 100 keV argon ions at fluences 1 � 1015, 5 � 1015 and 1 � 1016 ions/cm2 to be employed for optical and structural studies. The changes in transmittance, reflectance, optical energy gap and refractive index have been studied through the UV�Vis�NIR spectroscopic technique. The enhancement in reflectivity and a strong reduction in transmittance, particularly in the UV region, are observed after Ar+ implantation in CR-39 samples. The absorbance value remains low ~0.10, 0.15 and 0.20 in the key communication wavelength region i.e. 800�1600 nm for sample implanted at the fluence of 1 � 1015, 5 � 1015, 1 � 1016 Ar+/cm2, respectively. The Optical energy gap (EOPT) is determined to be 0.92 eV for the implanted layer of the sample implanted at the fluence of 1 � 1016 Ar+/cm2, whereas 3.70 eV for the pristine sample. The surface electrical conductivity is increased from ~1.49 � 10?14 S (pristine sample) to ~8.34 � 10?10 S for sample implanted at the fluence of 1 � 1016 Ar+/cm2. The formation of conjugated ?-bond (-C[dbnd]C-) structure with Ar+ implantation is confirmed via FTIR and Raman measurements. TGA results are analysed in detail and are found to be in strong agreement with the changes observed in different properties of CR-39 after ion implantation. � 2021 Elsevier B.V.
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    Role of energy loss-range profile of heavy ions in tailoring the optical properties of polycarbonate
    (Elsevier B.V., 2021-09-27T00:00:00) Chhokkar, Preeti; Kumar, V.; Goyal, Parveen K.; Kumar, Shyam; Tomar, A.K.; Gaur, Anurag; Arya, Anil
    Polycarbonate (PC) samples have been implanted with 115 keV N+, Ar+ and Kr+ at fluences ranging from 5x1014 to 1x1016 ions/cm2 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/cm2 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/cm2 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. � 2021 Elsevier B.V.