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Graduate Center of the City University of New York
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Radiation Effects and Defects in Solids
ABSTRACT The self-standing films of polymethyl methacrylate (PMMA) were irradiated under vacuum w... more ABSTRACT The self-standing films of polymethyl methacrylate (PMMA) were irradiated under vacuum with 50 MeV lithium (Li3+) and 80 MeV carbon (C5+) ions to the fluences of 3 × 1014, 1 × 1015, 1 × 1016 and 1 × 1017 ions µm−2. The pristine and irradiated samples of PMMA films were studied by using ultraviolet–visible (UV–Vis) spectrophotometry, Fourier transform infrared, X-ray diffractrometer and atomic force microscopy. With increasing ion fluence of swift heavy ion (SHI), PMMA suffers degradation, UV–Vis spectra show a shift in the absorption band from the UV towards visible, attributing the formation of the modified system of bonds. Eg and Ea decrease with increasing ion fluence. The size of crystallite and crystallinity percentage decreases with increasing ion fluence. With SHI irradiation, the intensity of IR bands and characteristic bands of different functional groups are found to shift drastically. The change in (Eg) and (N) in carbon cluster is calculated. Shifting of the absorption band from the UV towards visible along with optical activity and as a result of irradiation, some defects are created in the polymer causing the formation of conjugated bonds and carbon clusters in the polymer, which in turn lead to the modification in optical properties that could be useful in the fabrication of optoelectronic devices, gas sensing, electromagnetic shielding and drug delivery.
The self-standing films of non-conducting polymethyl methacrylate (PMMA) were irradiated in vacuu... more The self-standing films of non-conducting polymethyl methacrylate (PMMA) were irradiated in vacuum using high energy light ions (HELIs) of 50 MeV Lithium (Li +3 ) and 80 MeV Carbon (C +5 ) at various ion dose to induce the optical changes in the films. Upon HELI irradiation, films exhibit a significant enhancement in optical reflectivity at the highest dose. Interestingly, the photoluminescence (PL) emission band with green light at (514.5 nm) shows a noticeable increase in the intensity with increasing ion dose for both ions. However, the rate of increase in PL intensity is different for both HELI and can be correlated with the linear energy transfer by these ions in the films. Origin of PL is attributed to the formation of carbon cluster and hydrogenated amorphous carbon in the polymer films. HAC clusters act as PL active centres with optical reflectivity. Most of the harmful radiation like UV are absorbed by the material and is becoming opaque after irradiation and this PL active...
IOP Conference Series: Materials Science and Engineering
The effects of multi walled carbon nanotube (MWCNT) as well as swift heavy ion (SHI) irradiation ... more The effects of multi walled carbon nanotube (MWCNT) as well as swift heavy ion (SHI) irradiation on the optical and electrical properties of polymethyl methacrylate (PMMA) have been investigated. The self-sustaining films of non-conducting PMMA and PMMA/MWCNT nanocomposites were irradiated under vacuum with 50 MeV Lithium (Li 3+) and 80 MeV Carbon (C 5+) at 1×10 13 ion fluence. One peak photoluminescence (PL) band was found in Raman spectra. All these results were explained on the basis of charge transfer complex (CTC). Keywords: Hydrogenated amorphous carbon (HAC), Multiwalled carbon nanotubes (MWCNT), Polymethyl meth acrylate (PMMA), and Swift heavy ion (SHI).
Radiation Effects and Defects in Solids
ABSTRACT The self-standing films of polymethyl methacrylate (PMMA) were irradiated under vacuum w... more ABSTRACT The self-standing films of polymethyl methacrylate (PMMA) were irradiated under vacuum with 50 MeV lithium (Li3+) and 80 MeV carbon (C5+) ions to the fluences of 3 × 1014, 1 × 1015, 1 × 1016 and 1 × 1017 ions µm−2. The pristine and irradiated samples of PMMA films were studied by using ultraviolet–visible (UV–Vis) spectrophotometry, Fourier transform infrared, X-ray diffractrometer and atomic force microscopy. With increasing ion fluence of swift heavy ion (SHI), PMMA suffers degradation, UV–Vis spectra show a shift in the absorption band from the UV towards visible, attributing the formation of the modified system of bonds. Eg and Ea decrease with increasing ion fluence. The size of crystallite and crystallinity percentage decreases with increasing ion fluence. With SHI irradiation, the intensity of IR bands and characteristic bands of different functional groups are found to shift drastically. The change in (Eg) and (N) in carbon cluster is calculated. Shifting of the absorption band from the UV towards visible along with optical activity and as a result of irradiation, some defects are created in the polymer causing the formation of conjugated bonds and carbon clusters in the polymer, which in turn lead to the modification in optical properties that could be useful in the fabrication of optoelectronic devices, gas sensing, electromagnetic shielding and drug delivery.
The self-standing films of non-conducting polymethyl methacrylate (PMMA) were irradiated in vacuu... more The self-standing films of non-conducting polymethyl methacrylate (PMMA) were irradiated in vacuum using high energy light ions (HELIs) of 50 MeV Lithium (Li +3 ) and 80 MeV Carbon (C +5 ) at various ion dose to induce the optical changes in the films. Upon HELI irradiation, films exhibit a significant enhancement in optical reflectivity at the highest dose. Interestingly, the photoluminescence (PL) emission band with green light at (514.5 nm) shows a noticeable increase in the intensity with increasing ion dose for both ions. However, the rate of increase in PL intensity is different for both HELI and can be correlated with the linear energy transfer by these ions in the films. Origin of PL is attributed to the formation of carbon cluster and hydrogenated amorphous carbon in the polymer films. HAC clusters act as PL active centres with optical reflectivity. Most of the harmful radiation like UV are absorbed by the material and is becoming opaque after irradiation and this PL active...
IOP Conference Series: Materials Science and Engineering
The effects of multi walled carbon nanotube (MWCNT) as well as swift heavy ion (SHI) irradiation ... more The effects of multi walled carbon nanotube (MWCNT) as well as swift heavy ion (SHI) irradiation on the optical and electrical properties of polymethyl methacrylate (PMMA) have been investigated. The self-sustaining films of non-conducting PMMA and PMMA/MWCNT nanocomposites were irradiated under vacuum with 50 MeV Lithium (Li 3+) and 80 MeV Carbon (C 5+) at 1×10 13 ion fluence. One peak photoluminescence (PL) band was found in Raman spectra. All these results were explained on the basis of charge transfer complex (CTC). Keywords: Hydrogenated amorphous carbon (HAC), Multiwalled carbon nanotubes (MWCNT), Polymethyl meth acrylate (PMMA), and Swift heavy ion (SHI).