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Electron Irradiation (electron + irradiation)

Distribution by Scientific Domains

Polymers and Materials Science	55%
Physics and Astronomy	16%
Chemistry	16%

Selected Abstracts

Controlled Synthesis of Abundantly Branched, Hierarchical Nanotrees by Electron Irradiation of Polymers,

ADVANCED MATERIALS, Issue 1 2006
O. Cho
Hierarchical silicon oxycarbide tree-like nanostructures, which consist of trunks and abundant branches, have been fabricated by electron irradiation of organosilicon polymers. The nanotree structures have two different morphologies, cluster-assembled and nanowire-assembled. The morphology of the nanotrees can be controlled by the irradiation parameters. The proposed approach promises a straightforward means to fabricate complex hierarchical organic,inorganic nanostructures. [source]

Precipitation of MgO·nAl2O3 in Mg-Doped ,-Al2O3 under Electron Irradiation

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 1 2003
Kenji Kaneko
A number of nanoscale precipitates with random orientations were produced by electron irradiation of polycrystalline Mg-doped ,-Al2O3. The precipitation behavior and microstructural changes were observed using in situ high-resolution transmission electron microscopy. A ring pattern corresponding to a polycrystalline fcc structure was obtained from the region of these precipitates by selected-area diffraction, and they were identified as nonstoichiometric MgO·nAl2O3. It is believed that Al2O3 with MgO(ss) and/or MgO at the grain boundaries is effectively stabilized by the electron irradiation process, forming the fundamental structure of MgO·nAl2O3. The average size of the precipitates is about 10 nm. [source]

Carbon Nanotube Junctions: Multibranched Junctions of Carbon Nanotubes via Cobalt Particles (Adv. Mater.

ADVANCED MATERIALS, Issue 44 2009
44/2009)
Junctions between different carbon nanotubes (CNTs) created using cobalt particles as central nodes (background) are demonstrated by Ming-Sheng Wang and co-workers on p. 4477. The process involves high-temperature electron irradiation of areas where a metal particle is located at the overlapping region of two CNTs. In situ transmission electron microscopy measurements show that the junctions are electrically conductive and mechanically robust. The extension of this technique towards creating more complicated structures, such as a 3D CNT network, is also depicted in the cover. [source]

Multibranched Junctions of Carbon Nanotubes via Cobalt Particles

ADVANCED MATERIALS, Issue 44 2009
Julio A. Rodríguez-Manzo
Junctions between different carbon nanotubes are created using cobalt particles as central nodes (see image). The process involves high temperature and electron irradiation of areas where a metal particle is located at the overlapping region of two nanotubes. In situ transmission electron microscopy measurements show that the junctions are electrically conductive and mechanically robust. A high breaking strength of 1,5,GPa is found for the junctions. [source]

One Nanometer Thin Carbon Nanosheets with Tunable Conductivity and Stiffness

ADVANCED MATERIALS, Issue 12 2009
Andrey Turchanin
Atomically thin (,1,nm) carbon films and membranes whose electrical behavior can be tuned from insulating to conducting are fabricated by a novel route. These films present arbitrary size and shape based on molecular self-assembly, electron irradiation, and pyrolysis, and their technical applicability is demonstrated by their incorporation into a microscopic pressure sensor. [source]

Controlled Synthesis of Abundantly Branched, Hierarchical Nanotrees by Electron Irradiation of Polymers,

Chemical modification of polystyrene by low-energy (<100 eV) electron irradiation studied by mass spectrometry

JOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2008
S. Massey
Abstract Dip-coated thin films of polystyrene were chemically modified (degraded) by low-energy electron irradiation (0,100 eV). The resulting degradation was studied by mass spectrometry with variable electron energy. In the negative-ion mode, H, was observed and was associated with two phenomena. The resonant structure at 9.1 ± 0.4 eV was associated with dissociative electron attachment. The energy of the resonance peak agreed with the results obtained for organic molecules. At a higher energy, a monotonic rise of the emission yield was observed and was associated with nonresonant dipolar dissociation. More mass fragments were observed in the positive-ion mode. The predominant ion was H+ at 100 eV of electron irradiation, and alkyl ions were detected at higher masses. Emission thresholds were measured for the most predominant positive ions. The shape of the emission curve showed that there was no resonant process in the formation of these ions. The energy threshold was measured at about 20 eV, and this meant that the carbon structure of the polymer broke with a recombination of the degradation products with hydrogen atoms before the emission occurred. Below 19 eV, there was only hydrogen loss; this implied that the possible degradation mechanisms did not break the general carbon structure of the material, leading to crosslinking. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source]

Analyses of the factors for the demagnetization of permanent magnets caused by high-energy electron irradiation

JOURNAL OF SYNCHROTRON RADIATION, Issue 3 2009
Yoshihiro Asano
Demagnetization owing to high-energy electron irradiation has been analyzed for permanent magnets used in insertion devices of synchrotron radiation sources, using the Monte Carlo code FLUKA. The experimental data of a thermally treated Nd2Fe14B permanent magnet with a copper or a tantalum block at electron energies ranging from 2 to 8,GeV were compared with the calculation data of the absorbed doses, photoneutron production distributions and star densities. The results indicate that low-energy photoneutrons and bremsstrahlung photons are not involved in the demagnetization process, and suggest that the star density owing to the photoneutrons is strongly correlated with the demagnetization process. [source]

Precipitation of MgO·nAl2O3 in Mg-Doped ,-Al2O3 under Electron Irradiation

Role of total skin electron beam therapy for leukemia cutis in pediatric patients

PEDIATRIC BLOOD & CANCER, Issue 5 2008
Joseph M. Pepek MD
Abstract The role of radiation therapy for those with leukemia cutis, particularly pediatric patients, remains unclear. This report describes the first two cases of disseminated leukemia cutis in adolescents treated with total skin electron beam therapy. Both patients had resolution of their skin disease and significant palliation of symptoms. Total skin electron irradiation is an option for adolescents suffering from significant extramedullary leukemia involving the skin. While it is uncertain if this treatment has any improvement in disease-free survival, the benefits of total skin electron therapy for symptom palliation should be considered. Pediatr Blood Cancer 2008;50:1054,1055. © 2007 Wiley-Liss, Inc. [source]

Multi-peak structure of the kinetic-energy distribution of Na+ desorbed from NaCl during electron irradiation

PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 2 2003
L. Markowski
Abstract Results of electron-stimulated desorption of positive ions measured by the time-of-flight method from thin NaCl layers deposited onto Si(111) crystal are presented. The kinetic-energy distribution of Na+ is characterized by at least a double-peak structure suggesting desorption by the wave packet squeezing process, proposed recently for Li+ desorption from LiF. Moreover, a delayed Na+ signal is observed, indicating desorption of core-excited Na** atoms being in metastable autoionizing states. [source]

Positron annihilation characteristics in UO2: for lattice and vacancy defects induced by electron irradiation

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 10 2007
M.-F. Barthe
Abstract In this work both 22Na based positron lifetime spectroscopy (PALS) and slow positron beam based Doppler annihilation-ray broadening spectrometry (SPBDB) have been used to characterize respectively the bulk and the first micron under the surface of sintered UO2 disks that have been polished and annealed at high temperature (1700 °C/24 h/ArH2). Results show the presence of negative ions that are tentatively identified to negatively charged oxygen atoms located in interstitial sites. The positron annihilation characteristics in the UO2 lattice have been determined and are equal to SL(UO2) = 0.371(5), WL(UO2) = 0.078(7), ,L(UO2) = 169 ± 1 ps. Such disks have been irradiated at room temperature with electrons and , particles at different fluences. After irradiation SPBDB and PALS measurements show the formation of U-related vacancy defects after a 2.5 MeV electrons irradiation whereas no defects are detected for an irradiation at 1 MeV. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

GaAs solar cells grown on Si substrates for space use

PROGRESS IN PHOTOVOLTAICS: RESEARCH & APPLICATIONS, Issue 3 2001
Masafumi Yamaguchi
GaAs single-junction and InGaP/GaAs multi-junction thin-film solar cells fabricated on Si substrates have great potential for high-efficiency, low-cost, lightweight and large-area space solar cells. Heteroepitaxy of GaAs thin films on Si substrates has been examined and high-efficiency GaAs thin-film solar cells with total-area efficiencies of 18·3% at AM0 and 20·0% at AM 1·5 on Si substrates (GaAs-on-Si solar cells) have been fabricated. In addition, 1-MeV electron irradiation damage to GaAs-on-Si cells has been studied. The GaAs-on-Si cells are found to show higher end-of-life efficiency than the conventional GaAs cells fabricated on GaAs substrates (GaAs- on-GaAs cells) under high-fluence 1-MeV electron irradiation of more than 1,×,1015,cm,2. The first space flight to make use of them has been carried out. Forty-eight 2,×,2,cm GaAs-on-Si cells with an average AM0 total-area efficiency of 16·9% have been evaluated in the Engineering Test Satellite No.6 (ETS-VI). The GaAs-on-Si cells have been demonstrated to be more radiation-resistant in space than GaAs-on-GaAs cells and 50, 100 and 200-,m-thick Si cells. These results show that the GaAs-on-Si single-junction and InGaP/GaAs-on-Si multi-junction cells have great potential for space applications. Copyright © 2001 John Wiley & Sons, Ltd. [source]

On the crystal structure of Cr2N precipitates in high-nitrogen austenitic stainless steel.

ACTA CRYSTALLOGRAPHICA SECTION B, Issue 2 2006

The crystal structure and order,disorder transition of Cr2N were investigated utilizing transmission electron microscopy (TEM). Based on the analyses of selected-area diffraction (SAD) patterns, the crystal structure of the ordered Cr2N superstructure was confirmed to be trigonal (), characterized by three sets of superlattice reflections (001), (0) and (1). During electron irradiation, the superlattice reflections gradually disappeared in the regular sequence (001), (0) and (1), indicating that the order,disorder phase transition of Cr2N occurred. The convergent-beam electron diffraction (CBED) observation revealed that the space group of disordered Cr2N is P63/mmc, which corresponds to an h.c.p. (hexagonal close packed) sublattice of metal atoms with a random distribution of N atoms in six octahedral interstices. The redistribution model of N atoms through the order,disorder transition is discussed based on the characteristics and disappearing sequence of superlattice reflections. [source]