MeV Electron Beam Irradiation Research Articles

Synthesis and characterisation of starch grafted superabsorbent via 10 MeV electron-beam irradiation

A starch-graft-polyacrylamide (St-g-PAM) superabsorbent crosslinked by N,N′-methyl bisacrylamide (MBA) was prepared using 10MeV simultaneous electron beam irradiation at room temperature and subsequent alkaline hydrolysis. The effects of the irradiation dose, acryliamide-to-anhydroglucose unit (AM-to-AGU) ratio and crosslinker amount on the properties of the obtained polymers were evaluated. The structure of the graft copolymer was confirmed by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM). Optimisation treatments were carried out and found for a total dose of 8kGy, an AM-to-AGU ratio of 4.5molmol−1 and a crosslinker-to-AM ratio of 0.4%mol mol−1. The obtained superabsorbent polymer showed the maximum absorptions of 1452gg−1 and 83gg−1 for distilled water and saline solution, respectively (relative to its own dry weight). The results suggest 10MeV electron beam irradiation is more efficient than γ-ray irradiation due to its higher energy and dose rate.

The effects of electron irradiation on the optical properties of the organic semiconductor polypyrrole

The optical properties of polypyrrole (Ppy) thin films upon 2 MeV electron beam irradiation changes with different doses. The induced changes in the optical properties for Ppy thin films were studied in the visible range 300 to 800 nm at room temperature. The optical band gap of the pristine Ppy was found to be 2.19 eV and it decreases up to 1.97 eV for a 50 kGy dose of 2 MeV electron beam. The refractive index dispersion of the samples obeys the single oscillator model. The obtained results suggest that electron beam irradiation changes the optical parameters of Ppy thin films.

Formation of uniformly sized gold nanoparticles over graphene by MeV electron beam irradiation for transparent conducting films

Highly flexible, transparent, and conducting sheet was fabricated by decoration of uniformly sized gold nanoparticles (Au NPs) with high-density on large-area graphene by MeV electron beam irradiation (MEBI) at room temperature under ambient conditions. The Au NPs with an average size of 13.6 ± 3.5 nm were clearly decorated on the graphene after MEBI with an irradiation energy of 1.0 MeV. The sheet resistances of the Au NPs/graphene significantly decreased. For the Au NPs/trilayer graphene, the sheet resistance reached to ∼45 Ω/sq, and the optical transmittance was ∼90.2% which is comparable to that of conventional indium tin oxide film.

MeV Electron-Beam Induced Clusterization of Platinum Chloride on Graphene for Transparent Conductive Electrodes

The use of graphene-based transparent conductive electrodes critically depends upon the enhancement of electrical conductivity with a negligible loss of optical transmittance of graphene. Hence, the hybridization of graphene and metal nanostructures has been intensively investigated to improve electrical conductivity. Here we demonstrate clusterization of PtCl2 on graphene by a facile method, MeV electron-beam irradiation (MEBI) under ambient conditions, as characterized by scanning electron microscopy, transmittance electron microscopy, and resonant Raman spectroscopy. The workfunction difference between PtCl2 nanoclusters and graphene results in p-type doping of graphene, to achieve a reduced sheet resistance of 69.1 % with respect to that of pristine graphene while maintaining transmittance of 91.7 %. The mechanism of formation of PtCl2 nanoclusters on graphene is likely to be defect-mediated clusterization due to the high energy electron-beam.

Reversible growth of UO2 nanoparticles in aqueous solutions through 7 MeV electron beam irradiation

Uranium dioxide (UO2) nanoparticles of rod-shaped structures with diameter 80nm and length 500nm, have been grown in aqueous solutions of uranyl nitrate with electron beam irradiation using a 7MeV linear electron accelerator. These nanoparticles were found to be stable under de-aerated condition; however they decomposed upon exposure to air or oxygen. The bimolecular rate constant for decomposition of these nanoparticles has been estimated to be 4.3×10−1M−1s−1, in the aerated and oxygen saturated solutions, assuming these to be of pseudo-first order processes. The nitrogen-purged decomposed solution again produced the black coloured UO2 sol upon such irradiation and these reversible phenomena could be repeated for several cycles. There was also decomposition of the UO2 nanoparticles along with evolution of hydrogen upon addition of acid in the de-aerated condition.

Homogeneous and stable p-type doping of graphene by MeV electron beam-stimulated hybridization with ZnO thin films

In this work, we demonstrate a unique and facile methodology for the homogenous and stable p-type doping of graphene by hybridization with ZnO thin films fabricated by MeV electron beam irradiation (MEBI) under ambient conditions. The formation of the ZnO/graphene hybrid nanostructure was attributed to MEBI-stimulated dissociation of zinc acetate dihydrate and a subsequent oxidation process. A ZnO thin film with an ultra-flat surface and uniform thickness was formed on graphene. We found that homogeneous and stable p-type doping was achieved by charge transfer from the graphene to the ZnO film.

电子束辐照对GaN基LED发光性能的影响

The influence of different energy electron beam irradiation on the luminescence properties of GaN-based LED has been studied.GaN-based LED epitaxial wafers are irradiated under the simulation of space electron radiation by 1.5,3.0,4.5 MeV electron beam irradiation in the laboratory and photoluminescence(PL) spectra is applied to measure luminescent properties.The results show that LED luminous intensity increase about 25% when the radiation doses is 10 kGy with electron energy is 1.5 MeV,while reduced ~16% in dose irradiation in 100 kGy.Under 3 MeV electron beam irradiation,the color purity of LED increased,while in the higher energy irradiation the device failed.

Morphological changes in nanoparticulate silver films due to electron beam irradiation of polystyrene substrates

Results of the studies on the effect of 8 MeV electron beam irradiation of polystyrene substrates on the morphology of silver particulate films deposited at 455 K in a vacuum of 8 × 10 −6 Torr are reported. Optical absorption studies show the presence of transverse and longitudinal plasmon resonance for films deposited on irradiated polystyrene. Scanning electron microscopy reveals a decrease in particle size with smaller inter-particle separation for irradiated films. Larger clusters are formed in the case of films deposited on polystyrene after 300 h of irradiation. In this paper, we show that the morphology of silver nanoparticulate films can be modified by electron irradiation of inert polymer substrates like polystyrene. The change observed due to irradiation is attributed to the formation of free radicals, thereby altering the polymer–metal interaction.

Anchoring Au and Pt Nanoparticles on Multiwalled Carbon Nanotubes via Electron Beam Induced Amorphous Carbon Encapsulation

Au and Pt nanoparticles (NPs) were anchored on multiwalled carbon nanotubes (MWCNTs) via electron beam induced amorphous carbon encapsulation by energy-tunable MeV electron beam irradiation (MEBI) under ambient conditions. MEBI allowed the formation of size-homogeneous Au and Pt NPs on MWCNTs, as observed by transmission electron microscopy. Anchoring of metal NPs was achieved by MEBI-induced amorphous carbon encapsulation. The chemical doping effects of Au and Pt NPs were also verified by Raman spectroscopy. MEBI may provide a facile methodology for anchoring metal NPs to enhance electrical conductivity without destruction of MWCNTs.

Anchoring Au and Pt Nanoparticles on Multiwalled Carbon Nanotubes via Electron Beam Induced Amorphous Carbon Encapsulation

Au and Pt nanoparticles (NPs) were anchored on multiwalled carbon nanotubes (MWCNTs) via electron beam induced amorphous carbon encapsulation by energy-tunable MeV electron beam irradiation (MEBI) under ambient conditions. MEBI allowed the formation of size-homogeneous Au and Pt NPs on MWCNTs, as observed by transmission electron microscopy. Anchoring of metal NPs was achieved by MEBI-induced amorphous carbon encapsulation. The chemical doping effects of Au and Pt NPs were also verified by Raman spectroscopy. MEBI may provide a facile methodology for anchoring metal NPs to enhance electrical conductivity without destruction of MWCNTs.

The decoration of multi-walled carbon nanotubes with metal nanoparticles of uniform size using MeV electron beam irradiation

An easy method for decorating multi-walled carbon nanotubes (MWCNTs) with metal nanoparticles (NPs) of a uniform size is reported. The NPs were obtained by energy-tunable MeV electron beam irradiation (MEBI) on NiCl 2·6H 2O-coated and PtCl 2-coated MWCNTs at room temperature and ambient conditions. X-ray photoelectron spectroscopy clearly revealed that MEBI induced Cl desorption, leading to the formation of Ni (5.16 ± 0.74 nm) and Pt (1.63 ± 0.15 nm) NPs. Since this was achieved without destruction of MWCNTs, MEBI can be a universal method for obtaining any metal NP on CNTs if the metal forms a compound with Cl.

Electrical properties of Ge nanocrystals grown in a SiO2 matrix using MeV electron beam irradiation

AbstractThe structural and electrical properties of Ge nanocrystals (Ge‐NCs) grown in a SiO2 matrix using high energy electron beam irradiation are investigated. The Ge‐NCs in a SiO2 were formed by irradiation of the electron beam on a tri‐layers (SiO2(20 nm)/Ge(5 nm)/SiO2(10 nm)) grown on a Si(001) substrate and followed by annealing. For a sample exposed in the atmosphere by electron beam with energy of 1 MeV and a dose of ∼5 × 1016 e/cm2, and then annealed at 700 °C for 10 min, transmission electron microscopy (TEM) measurement revealed the formation of Ge‐NCs with average size of ∼20 nm in a SiO2 matrix. For a metal–oxide–semiconductor (MOS) structure synthesized by Al deposition on the top of the sample, the capacitance–voltage (C –V) measurements showed the hysteresis loops with a flatband voltage shift (ΔVFB) of ∼5.0 V, which would originate mainly from Ge‐NCs as the charge storage nodes. In contrast, for a sample annealed at above 900 °C for 10 min without electron beam irradiation, we could obtain a similar hysteresis loop of ∼4.0 V. This indicates that the e‐beam irradiation process can lead to temperature reduction of ∼200 °C for Ge‐NCs formation by annealing process. We propose that the temperature reduction would result from crystallity enhancement of Ge layers in the initial stage of Ge‐NCs formation due to Ge atomic displacements induced by the high energy electron beam. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Effect of electron beam treatments on degradation kinetics of polylactic acid (PLA) plastic waste under backyard composting conditions

AbstractThe effects of electron beam irradiation on backyard composting behaviour of polylactic acid (PLA) polymer were evaluated. Samples (10 mm2 × 0.75 mm) from thermoformed PLA drinking cups were exposed to 10 MeV electron beam irradiation at doses of 0, 72, 144 and 216 kGy. Irradiated PLA samples were placed in heat‐sealed, plastic screen and added to organic feedstock in a rotating composter within a computer‐controlled environmental chamber for 10 weeks at 35°C. Changes in weight, structural integrity and molecular weight were assessed over time. Results show that irradiation enhanced PLA breakdown. PLA weight decreased by increasing amounts as irradiation dose increased. Sample brittleness increased with irradiation dose and composting time. Finally, PLA molecular weight decreased as irradiation dose and compost time increased. Molecular weight D values for irradiated PLA were found to be about 430 kGy. After 1 week in a typical backyard composter, molecular weight D values increased to about 560 kGy and then fell to about 380 kGy after 2 weeks of composting. Samples irradiated at 216 kGy showed a reduction in weight of 9.4% after 10 weeks of composting, and a reduction of weight‐average molecular weight of 93.7% after 6 weeks. Copyright © 2008 John Wiley & Sons, Ltd.

Preparation of crosslinked chitosan by electron beam irradiation in the presence of CCl4

AbstractIn this article, we report the synthesis of crosslinked chitosan using 8 MeV electron beam (EB) irradiation in the presence of carbon tetrachloride. The crosslinked chitosan is characterized by dissolution, Fourier transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD), scanning electron microscopy (SEM), differential scanning colorimetry (DSC), and nanoindentation studies. The insolubility of irradiated films in acetic acid indicates that chitosan has undergone crosslinking reaction. FTIR analysis also confirms the crosslinked structure of chitosan. Mechanical properties such as elastic modulus and hardness are calculated from the nanoindentation data. Modulus and hardness of chitosan increase with increase in the irradiation dose due to the increase in the crosslinking. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Effects of 1 MeV Electron Beam Irradiation on Multilayer Graphene Grown on 6H-SiC(0001)

Graphene layers grown on 6H-SiC(0001) were irradiated with 1 MeV electron beam to functionalize its surface. A surface analysis using atomic force microscopy, the near edge X-ray adsorption fine structure spectra of C K-edge, and photoemission spectroscopy suggests that the electron beam irradiation in ambient condition can induce oxidation of the graphene layer.

Chemical phase transitions of a Si oxide film on SiC by MeV electron beam irradiation

An ultrathin Si oxide film grown on a 6H-SiC(0001) wafer was irradiated with 1MeV electron beam to examine its effect on the chemical species of a Si oxide/SiC wafer, where the Si oxide film was composed of SiO2, Si suboxides (Si3+, Si2+, and Si1+), and Si oxycarbides (Si–C–O). Scanning photoelectron microscopy and Si 2p core-level spectroscopy show that e-beam irradiation induces chemical phase transitions from the Si suboxides and Si oxycarbides to SiO2. This suggests that e-beam irradiation is an efficient and simple method of producing a chemically uniform SiO2 film on SiC without thermal and chemical treatments.

Structure Change under 1 MeV Electron Beam Irradiation of Amorphous-contained Nano-sized W-dendrites Fabricated on Alumina Substrates with Electron-beam-induced Deposition

Structure Change under 1 MeV Electron Beam Irradiation of Amorphous-contained Nano-sized W-dendrites Fabricated on Alumina Substrates with Electron-beam-induced Deposition

Effect of electron beam irradiation on polypropylene films—dielectric and FT-IR studies

Electron beam treatment studies have been carried out to investigate the potential for improvements in the dielectric properties of polypropylene (PP) films, after 1.5 MeV electron beam irradiation. The irradiation doses were conducted at 295 and 1080 kGy. The induced changes in the ac conductivity σ ac and dielectric properties for the irradiated films were studied, in the frequency range 100 Hz–1 MHz at room temperature. A slight increase in absorbance (measured by FT-IR) for the irradiated films has been observed. Further, it has been also found that the value of σ ac increased linearly with increasing frequency, meanwhile the frequency exponent s decreased with increasing electron dose.

Crystallization under 1 MeV Electron Beam Irradiation of Nanometer-Sized W-Dendrites Fabricated on Alumina Substrates with Electron-Beam-Induced Deposition

Nanometer-sized W-dendritic form structure was fabricated with electron-beam-induced deposition (EBID) in a 200 kV transmission electron microscope. The as-prepared nanodendrites are composed of W-nanocrystals and amorphous. The as-prepared nanodendrites were then irradiated with 1 MeV electron beam in a high voltage transmission electron microscope. The effect of the irradiation is investigated. The irradiation transformed effectively almost all the amorphous part to crystalline state. Morphology of the nanodendrite also changes. The irradiation induced crystallization and morphology change are discussed.

Hydrogel Networks of Poly(ethylene oxide) Star‐Molecules Supported by Expanded Polytetrafluoroethylene Membranes: Characterization, Biocompatibility Evaluation and Glucose Diffusion Characteristics

The present work discusses the grafting by electron beam irradiation of poly(ethylene oxide) (PEO) star-shaped polymers onto porous expanded polytetrafluoroethylene (EXPTFE) surfaces. The resulting materials are intended to combine the good biocompatible properties of PEO with the outstanding mechanical properties of PTFE. The star-shaped PEOs were synthesized via anionic polymerization. 3 Mev electron beam irradiation was applied to graft these PEO stars onto porous EXPTFE surfaces. The hydrophobic EXPTFE surface had to be pre-modified with N-vinylpyrrolidone. ESCA was used to quantify the amount of grafted star-shaped PEO. Unmodified EXPTFE surfaces are well known, when implanted in a body, to be rapidly covered by a layer of cells and fibrin. The EXPTFE coated with PEO were implanted in the peritoneal cavity of rats (or under the back skin). This implantation did not induce any inflammation reactions and SEM analysis had attested the absence of adsorbed cells and fibrin. The glucose diffusion properties of these membranes were studied by a lag time analysis method and compared to those of pure PEO hydrogels. As expected, glucose diffuses through the hydrogel coated membrane and diffusion is not affected by the presence of the EXPTFE membrane.