Influence Of Electron Beam Irradiation Research Articles

The influence of electron beam irradiation conducted in air on the thermal, chemical, structural and surface properties of medical grade polyurethane

It is well known that polyurethane (PU) provides good irradiation resistance; however, extremely high irradiation doses can alter the structure and/or function of macromolecules, resulting in oxidation, chain scission and crosslinking. In this present study, modifications to the material characteristics resulting from irradiation were extensively examined through a broad array of analytical techniques. Fourier transform infrared spectroscopy (FTIR) revealed that there were a number of changes to the chemical structure after electron beam irradiation while dynamic frequency sweeps identified an occurrence of crosslinking particularly in the higher irradiation doses. The degree of crosslinking was further analysed by implementing the crosslink density experiment, which illustrated a high level of crosslinking at 200kGy only. X-ray diffraction (XRD) and differential scanning calorimetry (DSC) identified an increase in phase segregation and as a consequence it could lead to soft segment mobility. This increase in mobility could be responsible for an increase in the degree of chain orientation. Surface morphology of the electron beam irradiated material was determined using scanning electron microscope (SEM) imagery and this provided evidence that the surface of the material had clearly transformed with the development of additional ridges. The influence of such modifications initiated a significant reduction in the contact angle at the upper irradiation dose regime. Overall, this study demonstrated that the medical grade PU was highly affected by radiation exposure, particularly at high irradiation doses.

The structural and optical properties of supercontinuum emitting Si nanocrystals prepared by laser ablation in water

Laser ablation of Si(100) targets immersed in deionized water at room temperature was studied by applying the second harmonic of a ns pulsed Nd:YAG laser and by employing different methods for characterization of the resulting nanocrystals (NCs). Spontaneous Raman scattering showed first order Raman spectra of the Si NCs, which varied in their Raman shift and width. The Raman data were analyzed using a phonon confinement model, involving three-dimensional confinement and lognormal size distributions for the nanocrystallites constituting the samples, indicating the presence of particles greater than ∼2 nm diameter. High-resolution transmission electron microscopy and electron diffraction of the as-prepared samples showed NCs with diameters greater than ∼1.75 nm and quantum dots, corresponding to Si/SiOx. The optical properties of the Si NCs were studied with cathodoluminescence (CL) spectroscopy for sample temperatures in the 50–300 K range, which exhibited a supercontinuum emission ranging from the near ultraviolet to the red regions. The emission is characterized by four major emission bands, peaked at 1.88, 2.18, 2.64 and 3.44 eV, which practically remain at the same positions as the temperature is varied. These bands are assigned to excitonic recombination in the Si NCs, whose electron/hole transition energies are consistent with the quantum confinement of carriers in four size-dispersed groups of Si NCs. The influence of electron beam irradiation on the passivation of the NCs was examined, showing quenching of the CL as a function of electron-beam exposure time. This quenching is attributed to desorption of hydrogen, disruption of the NC surface passivation, and formation of nonradiative recombination channels involving surface states in the gap. The approach used in this study demonstrates the possibility of growing nano-scale Si crystals with the potential for incorporation into optoelectronic devices or for use in biomedical applications.

Influence of electron-beam irradiation in SEM on the cathodoluminescence and electron-beam-induced current in InGaN/GaN light-emitting diodes with a buried active region

The influence of irradiation in a scanning electron microscope on the optical properties inherent to light-emitting diodes (LEDs) with multiple InGaN/GaN quantum wells, assembled by means of the flip-chip mounting technique, has been investigated via the cathodoluminescence (CL) and electron-beam-induced current methods. It is demonstrated that the action of an electron beam qualitatively varies both these LEDs and structures with a thin upper GaN layer only at large beam energies. It has been revealed that irradiation not only leads to changes in the spectrum and intensity of CL but also decreases the energy corresponding to the excitation of emission associated with quantum wells. A similar effect is also observed in structures whose external quantum efficiency has been decreased several times due to long-running tests performed at an injection current density of 35 A/cm2 and a temperature of 100°C.

Study on the influence of electron beam irradiation on the thermal, mechanical, and rheological properties of ethylene-octene copolymer with high comonomer content

Ethylene-octene copolymer (EOC) was irradiated using electron beam irradiation at different dosages (30, 60, 90, and 120 kGy). Effect of irradiation dosage on thermal and mechanical properties was studied. When compared to low density polyethylene, EOC exhibited higher degree of crosslinking reflected in increased gel content, higher elastic modulus (G 0 ), and lower tan d obtained by rheology measurement at 150 � C. Crosslinking caused improvement in high-temperature creep and room temperature and also ele- vated temperature elastic properties. Differential scanning calorimetry revealed that e-beam irradiation has caused a gradual reduction in crystallinity and a presence of a fraction with higher melting temperature. In the case of EOC, as the extent of crosslinking increased, stress at break showed an increasing trend whereas irradiation dosage had an inverse effect on elongation at break. Radia- tion dosage has positive effect on thermal stability estimated by thermogravimetric analysis. After 30 min of thermal degradation at 220 � C, slightly higher C¼ ¼O peak for crosslinked sample was found by Fourier transform infrared spectroscopy while for room tem- perature samples no C¼ ¼O peak was detected. V C 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 128: 3026-3033, 2013

Theoretical study on influence of electron beam irradiation on the first-order hyperpolarizability of BBO crystals

A mechanism not based on the traditional thermodynamics effect but on the microscopic origin of the nonlinear effect was investigated for full consideration of the correlation between the e-beam irradiation electric field (IEF) and the properties of the nonlinear material BBO (β-BaB2O4). Firstly, the IEF magnitude is computed under different conditions of beam intensity, ray energy and radiation dose. Secondly, the relationship model of IEF and nonlinear coefficients is built according to quantum mechanics principle. The results show that low-energy irradiation of 0–400 MeV ray energy (corresponding to IEFs of 0–12 × 10−4 a.u.) has no obvious effect on the nonlinear optical properties of BBO crystals. When the energy is higher than 420 MeV (corresponding to an IEF of 13 × 10−4 a.u.), the hyperpolarizability changed significantly, indicating permanent damage of the BBO crystals. With an increase of the ray energy, βx and βy tend to decrease, but βz increases markedly especially when the ray energy is more than 450 MeV (corresponding to an IEF of 16 × 10−4 a.u.).

Influence of electron beam irradiation on growth of Phytophthora cinnamomi and its control in substrates

Very extensive production procedure, especially in plants growing under covering, require methods, which would allow quick elimination or substantial reduction of populations of specific pathogens without affecting the growth and development of the cultivated plants. Among soil-borne pathogens, the Phytophthora species are especially dangerous for horticultural plants. In this study, irradiation with electron beam was applied to control Phytophthora cinnamomi. The influence of irradiation dose on the reduction of in vitro growth and the population density of the pathogen in treated peat and its mixture with composted pine bark (1:1), as well as the health of Chamaecyparis lawsoniana and Lavandula angustifolia plants were evaluated. Application of irradiation at a dose of 1.5kGy completely inhibited the in vitro development of P. cinnamomi. This irradiation effect was connected with the disintegration of the hyphae and spores of the species. Irradiation of peat and its mixture with composted pine bark with 10kGy resulted in the inhibition of stem base rot development in Ch. lawsoniana. Symptoms of the disease were not observed when the substrates were treated with 15kGy. In the case of L. angustifolia, stem root rot was not observed on cuttings transplanted to infected peat irradiated at a dose of 10kGy. Irradiation of the horticultural substrates did not affect plant growth.

Influence of electron beam irradiation on physicochemical properties of poly(trimethylene carbonate)

Electron beam (EB) irradiation of poly(trimethylene carbonate) (PTMC), an amorphous, biodegradable polymer used in the field of biomaterials, results in predominant cross-linking and finally in the formation of gel fraction, thus enabling modification of physicochemical properties of this material without significant changes in its chemical structure. PTMC films ( M w : 167–553 kg mol −1) were irradiated with different doses using an electron accelerator. Irradiation with a standard sterilization dose of 25 kGy caused neither significant changes in the chemical composition of the polymer nor significant deterioration of its mechanical properties. Changes in viscosity-, number-, weight-, and z-average molecular weights of PTMC for doses lower than the gelation dose ( D g ) as well as gel–sol analysis and swelling tests for doses above D g indicate domination of cross-linking over degradation. EB irradiation can be considered as an effective tool for increasing the average molecular weight of PTMC and sterilization of PTMC-based biomaterials.

The influence of electron beam irradiation on colour stability and hardness of aesthetic brackets

Electron beam irradiation can be used to improve the mechanical properties of polymers. The aim of this study was to investigate the influence of electron beam irradiation with an energy dose of 100 kGy on the mechanical properties and colour stability of conventional polymer brackets and experimental filled composite brackets. The conventional brackets tested were Aesthetik-Line, Brillant, and Envision. The experimental brackets contained urethane dimethacrylate, as a monomer matrix and functional silane-treated SiO(2) fillers with a filler content of either 10 (Exper 1) or 40 (Exper 2) vol per cent. The influence of electron beam post-curing on Vickers hardness (VH) of the polymer brackets was investigated. Additionally, a possible discolouration of the brackets after electron beam irradiation was determined according to the three-dimensional L* a* b* colour space. The irradiated brackets were compared with untreated control groups. Statistical analysis was performed using the Wilcoxon test. With the exception of Brillant brackets, all investigated brackets showed a significant enhancement of VH after electron beam post-curing. However, the brackets suffered a significant increase in discolouration. Aesthetik-Line brackets showed the highest discolouration, ΔE, and Exper 2 brackets the lowest ΔE values. The discolouration of the examined brackets differed significantly. These results demonstrate that the mechanical properties of polymer brackets could be modified by electron beam irradiation. Nevertheless, clinical use of electron beam post-curing might be restricted because of unacceptable colour changes.

Electronic transport properties of In-doped ZnO nanobelts with different concentration

In this paper, zinc oxide (ZnO) nanobelts with five different indium (In) concentrations (1.98, 2.73, 3.33, 4.20, and 5.16 wt%) were prepared by simple vapor deposition with HAuCl(4) (1% solution) as catalyst. Detailed structural and compositional characterizations were performed by XRD, TEM, EDS, PL, and Raman spectroscopy. Moreover, the current-voltage (I-V) characteristics of In-doped ZnO nanobelts with different In concentrations were determined by nano-manipulation and measurement systems. The results show that the resistivity of these nanobelts decreases with increasing In concentration when the doping concentration of In is lower than 4.20%, but, on the contrary, when the In concentration is higher than 4.20% their resistivity increases. Also, all of the nanobelts keep ohmic contact very well. Simultaneously, the influence of electron beam irradiation (20 kV) on the nanobelts was studied, and it was found that electron beam irradiation can improve the conductivity of the nanobelts. Under the same voltage, the current increased gradually during irradiation until equilibrium was reached. The degree of influence of the irradiation on the resistivity of the nanobelts is the greatest when the In dopant concentration is 4.20%, which is suitable for making irradiation sensors.

Investigation of electrochemical properties of RuO 2 thin films modified by e-beam irradiation

The influence of electron beam irradiation on the electrochemical properties of electrodeposited RuO 2 thin films was investigated using a 1 MeV electron beam. Crystallinity change before and after electron beam irradiation was investigated by X-ray diffraction, and the oxidation state of ruthenium was determined by X-ray photoelectron spectroscopy. Scanning electron microscopy was utilized to examine the morphology of the films. The results show that electron beam irradiation altered the oxidation state of ruthenium and increased crystallinity. Cyclic voltammetry was employed to evaluate the electrochemical properties of the synthesized RuO 2 films in terms of their application as electrodes of electrochemical capacitors. RuO 2 irradiated with 40 kGy showed 2.7 times higher capacitance (520 Fg −1) than the as-electrodeposited sample (190 Fg −1).

Enhanced performance as a lithium-ion battery cathode of electrodeposited V2O5 thin films by e-beam irradiation

The influence of electron beam irradiation on the electrochemical properties of electrodeposited V2O5 thin films was investigated. V2O5 thin films were deposited electrochemically onto indium tin oxide-coated glass from an aqueous vanadyl sulfate hydrate (VOSO4⋅nH2O) solution using Pt and Ag/AgCl as the counter electrode and reference electrode, respectively. Electrodeposition was performed potentiostatically at 1.7 V vs. Ag/AgCl. Electrodeposited samples were then subjected to a 1-MeV electron beam using an electron beam accelerator at the Korea Atomic Energy Research Institute. For comparison, a control sample was not irradiated with the electron beam. Crystallinity change before and after electron beam irradiation was investigated by X-ray diffraction and the oxidation state of vanadium determined by X-ray photoelectron spectroscopy. Scanning electron microscopy was utilized to examine surface morphology. It was observed that electron beam irradiation altered the oxidation state of vanadium and increased crystallinity. Significant morphological changes of V2O5 thin films were also observed with electron beam irradiation. Cyclic voltammetry was employed to evaluate the electrochemical properties of the synthesized V2O5 films in terms of their application as electrodes of lithium-ion battery. Compared with the control sample, which was not irradiated with an electron beam, the electron beam-irradiated V2O5 specimens showed much higher capacitance.

电子束辐照对GaN基蓝光LED性能的影响

电子束辐照对GaN基蓝光LED性能的影响

Influence of electron beam radiation on mechanical and thermal properties of styrene‐butadiene‐styrene block copolymer

AbstractElectron beam crosslinking of elastomers is a special type of crosslinking technique that has gained importance over conventional chemical crosslinking method, because the former process is fast, pollution free, and simple. The technique involves the impingement of high‐energy electrons generated from electron accelerators and the subsequent production of free radicals on target elastomers. These radicals result in crosslinking of elastomers via radical–radical coupling. In the process, some chain scission may also take place. In this work, a high‐vinyl (∼ 50%) styrene‐butadiene‐styrene (S‐B‐S) block copolymer was used as the base polymer. An attempt was made to see the effect of electron beam radiation on the mechanical and thermal properties of the block copolymer. Radiation doses were varied from 25 to 300 kGy. Mechanical properties like tensile strength, elongation at break, modulus at different elongations, hardness, tear strength, crosslink density, and crosslink to chain scission of the irradiated samples were studied and compared with those of unirradiated ones. In this S‐B‐S block copolymer, a relatively low‐radiation dose was found effective in improving the level of mechanical properties. Differential scanning calorimeter and dynamic mechanical analyzer were used to study the thermal characteristics of the irradiated polymer. Influence of a stabilizer at different concentrations on the properties of S‐B‐S at varied radiation doses were also focused on. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

The influence of electron-beam irradiation on electrical characteristics of metal–insulator–semiconductor capacitors based on a high- k dielectric stack of HfTiSiO(N) and HfTiO(N) layers

We describe the influence of electron irradiation (at 30 kV with a dose of up to 100 μC/cm 2) on the electrical characteristics of metal–insulator–semiconductor structures based on a high- k dielectric stack of HfTiSiO(N) and HfTiO(N). The capacitance–voltage ( C– V) and current–voltage characteristics were investigated after irradiation and compared to those of unirradiated samples. To better understand the irradiation effect, the capacitance–voltage ( C– V) and current–voltage characteristics were also characterized for structures which were stressed at constant voltages. The irradiation induces a parallel shift of the C– V curves towards negative bias due to the introduction of positive charges in the bulk dielectric and semiconductor–dielectric interface. Annealing at 300 °C restored the C– V characteristics to those of the untreated state. A small decrease of the dielectric constant, from 11.7 to 10.7, was observed after irradiation. No measurable change in leakage current due to irradiation was observed.

The influence of electron-beam irradiation on some mechanical properties of commercial multilayer flexible packaging materials

The influence of electron-beam irradiation on mechanical properties of commercial multilayer flexible packaging materials based on coextruded and laminated polypropylene (PP), low-density polyethylene (LDPE), ethylene vinyl alcohol copolymer (EVOH) and poly(ethylene terephthalate) (PET), irradiated with doses up to 120 kGy, was studied. The tensile strength and elongation at break of the irradiated PET/PP film increase, while the penetration and sealing resistance decreased. In addition, the irradiated PET/LDPE/EVOH/LDPE film presented increase in the tensile strength on some radiation doses and decrease of the penetration and sealing resistance, except for sealing resistance at radiation dose of 15 kGy that resulted in a slight increase of ca 4%.

418 液晶TV大画面用シリカ系ガラスの靭性に及ぼす電子線照射の影響(知的材料・構造システム)

418 液晶TV大画面用シリカ系ガラスの靭性に及ぼす電子線照射の影響(知的材料・構造システム)

Influence of Electron-Beam Irradiation on Bioactive Compounds in Grapefruits (Citrus paradisi Macf.)

Phytochemical levels in fruits and vegetables can be affected by several postharvest factors. In the present study, the effect of electron-beam (E-beam) irradiation was studied on grapefruit bioactive compounds. 'Rio Red' and 'Marsh White' grapefruits were irradiated with E-beam at 0, 1.0, 2.5, 5.0, and 10.0 kGy. Changes of various bioactive compounds, such as vitamin C, flavonoids, carotenoids, furocoumarins, and limonoids, were measured. The acidity decreased slightly with an increasing E-beam dose, whereas the total soluble solids were increased. Irradiation did not affect the vitamin C content at 1 kGy; however, doses beyond 1 kGy significantly reduced the vitamin C content. Lycopene and beta-carotene did not change significantly from the irradiation. Lycopene levels decreased as the E-beam dose increased, while the beta-carotene content slightly increased. Dihydroxybergamottin levels exhibited a decreasing trend, while the bergamottin content did not change. Naringin, a major flavonoid of grapefruit, showed a significant increase over the control at 10 kGy in both 'Rio Red' and 'Marsh White'. Nomilin continued to decrease with an increasing dose of E-beam irradiation, while limonin levels remained the same at all of the doses. Low-dose E-beam irradiation has very little effect on the bioactive compounds and offers a safe alternative to existing postharvest treatments for the disinfection and decontamination of grapefruits.

Expansion of Stacking Faults by Electron-Beam Irradiation in 4H-SiC Diode Structure

The influence of electron-beam irradiation on defects in 4H-SiC diode structures was investigated by cathodoluminescence (CL) microscopy and spectroscopy. In addition to threading edge and screw dislocations, two types of stacking faults (SFs) were characterized by their emission energy, geometric shape, and the sensitivity of electron-beam irradiation. The SFs at λ = 425 nm (2.92 eV) expand from the surface of basal plane dislocation with line direction [11-20] and change their geometric shape by electron-beam irradiation. The SFs at λ = 471 nm (2.63 eV) are only slightly influenced by electron-beam irradiation. The former corresponds to the Shockley-type SFs previously observed in the degraded p-i-n diodes, and the latter to in-grown SFs with 8H structure. The panchromatic CL images constructed by the sum of monochromatic CL images suggest that there are nonradiative recombination centers in the vicinity of Shockley-type SFs. The nucleation sites and the driving force for SF expansion are discussed.

Evaluation of van der Waals forces between the carbon nanotube tip and gold surface under an electron microscope

Carbon nanotubes (CNTs) have been widely used as nanobuilding blocks to assemble nanostructures and nanodevices. Therefore, the interaction between a CNT and an environment is important. In the present study, the interaction forces, which consisted mainly of van der Waals forces, between a single multi-walled carbon nanotube tip and a gold surface were evaluated under a scanning electron microscope by means of nanorobotic manipulation. The influence of electron beam irradiation was also investigated. It was found that electron beam irradiation can increase the interaction forces by producing contamination at the contact area. The van der Waals forces were calculated theoretically and the theoretical values were close to the experimental values.

1345 ナイロンシートと異種高分子間の接着に及ぼす電子線照射の影響(J14-9 知的材料・構造システム(9) 炭素・ポリマー関連材料,ジョイントセッション,21世紀地球環境革命の機械工学:人・マイクロナノ・エネルギー・環境)

1345 ナイロンシートと異種高分子間の接着に及ぼす電子線照射の影響(J14-9 知的材料・構造システム(9) 炭素・ポリマー関連材料,ジョイントセッション,21世紀地球環境革命の機械工学:人・マイクロナノ・エネルギー・環境)