共查询到20条相似文献,搜索用时 18 毫秒
1.
K. Hirata Y. Saitoh K. Yamada K. Narumi 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2010,268(19):2930-2932
Emission yields of secondary ions necessary for the identification of poly-tyrosine were compared for incident ion impacts of energetic cluster ions (0.8 MeV , 2.4 MeV , and 4.0 MeV ) and swift heavy monoatomic molybdenum ions (4.0 MeV Mo+ and 14 MeV Mo4+) with similar mass to that of the cluster by time-of-flight secondary ion mass analysis combined with secondary ion electric current measurements. The comparison revealed that (1) secondary ion emission yields per impact increase with increasing incident energy within the energy range examined, (2) the 4.0 MeV impact provides higher emission yields than the impact of the monoatomic Mo ion with the same incident energy (4.0 MeV Mo+), and (3) the 2.4 MeV impact exhibits comparable emission yields to that for the Mo ion impact with higher incident energy (14 MeV Mo4+). Energetic cluster ion impacts effectively produce the characteristic secondary ions for poly-tyrosine, which is advantageous for highly sensitive amino acid detection in proteins using time-of-flight secondary ion mass analysis. 相似文献
2.
Single crystal 〈0 0 0 1〉-oriented 6H-SiC was irradiated with Au2+ ions to fluences of 0.032, 0.058 and 0.105 ions/nm2 at 140 K and was subsequently annealed at various temperatures up to 500 K. The relative disorder on both the Si and C sublattices has been determined simultaneously using in situ D+ ion channeling along the 〈0 0 0 1〉 and 〈〉 axes. A higher level of disorder on both the Si and C sublattices is observed along the 〈〉. There is a preferential C disordering and more C interstitials are aligned with 〈0 0 0 1〉. Room-temperature recovery along 〈〉 occurs, which is associated with the 〈0 0 0 1〉-aligned interstitials that annihilate due to close-pair recombination. Disorder recovery between 400 and 500 K is primarily attributed to annihilation of interstitials that are misaligned with 〈0 0 0 1〉 and to epitaxial crystallization. Effects of stacking order in SiC on disorder accumulation are insignificant; however, noticeable differences of low-temperature recovery in Au2+-irradiated 6H-SiC and 4H-SiC are observed. 相似文献
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C. Wrede K. Deryckx B.M. Freeman A. García G.C. Harper A.S.C. Palmer D.A. Short D.I. Will 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2010,268(23):3482-2729
The preparation of isotopically pure targets of 20Ne, 24Mg, 28Si, 32S, and 36Ar by the implantation of 25-70 keV ions into carbon foils is described. 相似文献
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Equilibrium constants for modeling surface precipitation of trivalent metal cations (M3+) onto hydrous ferric oxide and calcite were estimated from linear correlations of standard state Gibbs free energies of formation, () of the surface precipitates. The surface precipitation reactions were derived from Farley et. al. [K.J. Farley, D.A. Dzombak, F.M.M. Morel, J. Colloid Interface Sci. 106 (1985) 226] surface precipitation model, which are based on surface complexation model coupled with solid solution representation for surface precipitation on the solid surface. The values were correlated through the following linear free energy relations and where ‘ss’ stands for the end-member solid component of surface precipitate, is in kJ/mol, rM3+ is the Shannon-Prewitt radius of M3+ in a given coordination state (nm), and is the non-solvation contribution to the Gibbs free energy of formation of the aqueous M3+ ion. Results indicate that the above surface precipitation correlations are useful tools where experimental data are not available. 相似文献
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E. Wendler Th. Bierschenk E. Friedland 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2010,268(19):2996-3000
Rutherford backscattering spectrometry (RBS) in channelling mode was used to study the defect formation in silver (Ag) ion irradiated silicon carbide (SiC). The 4H-SiC samples were irradiated with 360 keV Ag ions at different temperatures (15, 295, 375, 475, 625 and 875 K) over a wide range of fluences (1×1011 to , depending on the irradiation temperature). The results can be divided into two groups: (i) for irradiation temperatures between 15 and 475 K amorphisation of the implanted layers is reached for ion fluences between 7×1013 and . The over-all cross-section of defect production at very low ion fluences which comprises the formation of point defects and of amorphous clusters, is almost identical for all data sets measured in this temperature range. Differences in the damage evolution which occur at higher ion fluences, suggest that the relative contribution of amorphous clusters within single ion impacts in crystalline material decreases with rising temperature. (ii) For irradiations performed at 625 and 875 K no amorphisation is found for ion fluences as high as . With increasing ion fluence the defect concentration exhibits a distinctive plateau due to the balance between formation and recombination of point defects before increasing up to a saturation level well below amorphisation. For this final stage our results indicate a mixture of point defect clusters and extended defects most probably dislocations. A comparison with data from the literature suggests that the damage evolution for implantation at 625 and 875 K is strongly influenced by the mobility of vacancies starting at around 600 K. 相似文献
6.
Haiyan Zhang Tingyu Liu Qiren Zhang Xi’en Wang Xiaofeng Guo Min Song Jigang Yin 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2009,267(7):1056-1060
The electronic structures, dielectric function and absorption spectra for the perfect BaWO4 (BWO) crystal and the BWO crystal containing barium vacancy () have been studied using density functional theory code CASTEP with the lattice structure optimized. The results indicate that the optical properties of the BWO crystal exhibit anisotropy and its optical symmetry coincide with lattice structure geometry of the BWO crystal. For the BWO crystal containing , there exhibit four absorption bands peaking at 0.71 eV (1751 nm), 1.85 eV (672 nm), 3.43 eV (362 nm) and 3.85 eV (322 nm), respectively. The origins of the 370 nm absorption band should be related to the . 相似文献
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Fang Cheng Qiren Zhang Hailin Qiao Xiuwen Zhou 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2010,268(15):2403-2407
The experiments indicate that the perfect KMgF3 crystal has no absorption in the visible range, however the electron irradiation induces a complex absorption spectrum. The absorption spectra can be decomposed by five Gaussian bands peaking at 2.5 eV (488 nm), 3.4 eV (359 nm), 4.2 eV (295 nm), 4.6 eV (270 nm) and 5.2 eV (239 nm), respectively. The purpose of this paper is to seek the origins of the absorption bands. The electronic structures and absorption spectra either for the perfect KMgF3 or for KMgF3: with electrical neutrality have been studied by using density functional theory code CASTEP with the lattice structure optimized. The calculation results predicate that KMgF3: also exhibits five absorption bands caused by the existence of the fluorine ion vacancy and the five absorption bands well coincide with the experimental results. It is believable that the five absorption bands are related to in KMgF3 crystal produced by the electron irradiation. 相似文献
8.
Crystallographic measurement of the β to α phase transformation and δ-hydride precipitation in a laser-welded Zircaloy-2 ferrule tube were carried out using an electron backscattering diffraction pattern (EBSP). A basket-weave structure with sub-micron lath width caused by quenching from the β to α phase was observed in the heat-affected and fusion zones, and mainly showed a grain boundary misorientation angle of 60° with an <1 1 0> rotation axis. This result is consistent with the Burgers orientation relationship of {1 1 0}β//(0 0 0 1)α and <1 1 1>β//<1 1 0>α for the β to α phase transformation. The texture of the quenched α′ phase was strongly inherited from the original α phase, having a radial (0 0 0 1) basal pole and axial {1 1 0} textures, even in the fusion zone. The primary hydride habit plane in the welded Zircaloy-2 was (0 0 0 1)α//{1 1 1}δ, matching previously obtained results for recrystallized cladding tubes. In addition to the primary habit plane, secondary habit planes were observed for the other low-index planes {1 0 0} and {1 0 1} in the fusion zone. The heterogeneous accumulation of hydrides in the transition zone between heat-affected and unaffected zones was mainly due to the residual stress distribution in the narrow region. 相似文献
9.
Aliaksandr Baidak 《Journal of Nuclear Materials》2010,407(3):211-219
Radiation-induced degradation of the strongly basic anion exchange resin Amberlite™ IRA400 in , Cl− and OH− forms has been studied. The research focused on the formation of molecular hydrogen in the gamma-radiolysis of water slurries of these quaternary ammonium resins with varying water content. Extended studies with various electron scavengers (, N2O and O2) prove an important role of in the formation of H2 from these resins. An excess production of H2 in these systems at about 85% water weight fraction was found to be due to trimethylamine, dimethylamine and other compounds that leach from the resin to the aqueous phase. Irradiations with 5 MeV 4He ions were performed to simulate the effects of α-particles. 相似文献
10.
The degree of embrittlement of the reactor pressure vessel (RPV) limits the lifetime of nuclear power plants. Therefore, neutron irradiation-induced embrittlement of RPV steels demands accurate monitoring. Current federal legislation requires a surveillance program in which specimens are placed inside the RPV for several years before their fracture toughness is determined by destructive Charpy impact testing. Measuring the changes in the thermoelectric properties of the material due to irradiation, is an alternative and non-destructive method for the diagnostics of material embrittlement. In this paper, the measurement of the Seebeck coefficient () of several Charpy specimens, made from two different grades of 22 NiMoCr 37 low-alloy steels, irradiated by neutrons with energies greater than 1 MeV, and fluencies ranging from 0 up to 4.5 × 1019 neutrons per cm2, are presented. Within this range, it was observed that increased by ≈500 nV/°C and a linear dependency was noted between and the temperature shift ΔT41 J of the Charpy energy vs. temperature curve, which is a measure for the embrittlement. We conclude that the change of the Seebeck coefficient has the potential for non-destructive monitoring of the neutron embrittlement of RPV steels if very precise measurements of the Seebeck coefficient are possible. 相似文献
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E.A.G. Armour A.C. Todd Y. Liu M. Plummer 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2008,266(3):363-368
In this paper, we describe calculations that we have carried out of cross sections for rearrangement processes in very low-energy helium + antihydrogen scattering that result in or or . A significantly more accurate method from that used previously [E.A.G. Armour, S. Jonsell, Y. Liu, A.C. Todd, Nucl. Instr. and Meth. B 247 (2006) 127] is used to calculate the entrance channel wave function. Results are presented for the first two processes. Mention is made of the use of the method in calculations of low-energy e+H2 scattering. 相似文献
13.
R.M. Kadam S.V. Godbole 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2008,266(24):5137-5143
Defect centers induced by gamma irradiation in Ce doped BaBPO5 were investigated using EPR spectroscopy. From EPR studies, three phosphorous centered radicals were characterized on the basis of observed 31P hyperfine splitting and g values as , and radicals. In addition to this, two types of boron oxygen hole centers (BOHC) and O− were also formed at room temperature. An intense broad signal in sample annealed in argon (g⊥ = 1.9258 and g‖ = 1.8839) was assigned to Ce3+ ions associated with the electron trapped at anion vacancy or nearby lattice defect. TSL studies showed two glow peaks, a relatively weaker one at 425 K and an intense one at 575 K. Spectral studies of the TSL glow peaks have shown that Ce3+ ion acts as emission center. From the temperature dependence of the EPR spectra of gamma irradiated samples, the glow peaks at 425 K and 575 K were attributed to thermal destruction of /O− and BOHC, respectively, by trapping of electrons from elsewhere. The energy released in electron hole recombination process is used for the excitation of Ce3+ ions resulting in these glow peaks at 425 K and 575 K. The spectral studies of the TSL glow peaks have shown emission at 330 nm indicating Ce3+ acts as the luminescent centre. The trap depth and the frequency factor for the 425 K and 575 K peaks were determined using different heating rates method. 相似文献
14.
L. Bettadj A. Surzhykov S. Fritzsche 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2010,268(23):3509-3516
The intensity ratio of the to photon emission is analyzed for hydrogen-like Fe25+ ions if their excitation arises in a plasma not only from the electron impact but also due to the radiative recombination (RR) of initially bare Fe26+ ions. Under such conditions, the intensity ratio and the (degree of) linear polarization of the Ly-α1 line are explored for collisions with an electron beam over a wide range of kinetic energies up to 50 keV. Apart from the direct population of the 2p1/2,3/2 levels via the RR of bare ions, the contributions from radiative cascades and higher multipoles are taken into account by applying a fully relativistic theory for the motion of the electrons and the electron-photon coupling. Our calculations show an overall small effect of the RR upon the degree of the Ly-α1 polarization as well as the intensity ratio under usual plasma conditions. However, the effects from the RR of initially bare ions may become significant at electron beam energies , for plasma conditions far away from ionization equilibrium with a relatively large proportion of bare Fe ions, as it may be realized in electron-beam ion trap experiments. 相似文献
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S. Phapale 《Journal of Nuclear Materials》2008,375(2):259-262
Thermodynamic properties of two intermetallic phases CdZr2(s) and Cd3Zr(s) in the binary Cd-Zr system have been investigated. The standard molar enthalpy of formation of CdZr2(s) and Cd3Zr(s) was obtained by measuring the reaction enthalpy of CdZr2(s), Cd3Zr(s) and Zr(s), respectively, using Cd(l) in a Calvet calorimeter. The values of of CdZr2(s) and Cd3Zr(s) at 298 K were found to be −(61.7 ± 1.2) kJ mol−1 and −(72.3 ± 0.9) kJ mol−1, respectively. 相似文献
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In order to elucidate the effect of noble metal clusters in spent nuclear fuel on the kinetics of radiation induced spent fuel dissolution we have used Pd particle doped UO2 pellets. The catalytic effect of Pd particles on the kinetics of radiation induced dissolution of UO2 during γ-irradiation in containing solutions purged with N2 and H2 was studied in this work. Four pellets with Pd concentrations of 0%, 0.1%, 1% and 3% were produced to mimic spent nuclear fuel. The pellets were placed in 10 mM aqueous solutions and γ-irradiated, and the dissolution of was measured spectrophotometrically as a function of time. Under N2 atmosphere, 3% Pd prevent the dissolution of uranium by reduction with the radiolytically produced H2, while the other pellets show a rate of dissolution of around 1.6 × 10−9 mol m−2 s−1. Under H2 atmosphere already 0.1% Pd effectively prevents the dissolution of uranium, while the rate of dissolution for the pellet without Pd is 1.4 × 10−9 mol m−2 s−1. It is also shown in experiments without radiation in aqueous solutions containing H2O2 and O2 that ?-particles catalyze the oxidation of the UO2 matrix by these molecular oxidants, and that the kinetics of the catalyzed reactions is close to diffusion controlled. 相似文献
20.
Y. Wang M. Qi D.X. Li 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2008,266(6):881-885
The morphology and interface structure of α-Fe2O3 islands grown on α-Al2O3 single crystals (sapphire) by Fe-ion-implantation and annealing in an oxidizing atmosphere have been studied using transmission electron microscopy. The α-Fe2O3 islands have the orientation relationship of and with sapphire. The typical outline of α-Fe2O3 islands consists of two (0 0 0 1) and six planes. The interfaces between α-Fe2O3 islands and sapphire are semicoherent, that is coherent regions separated by misfit dislocations at the interfaces. When imaged along the direction, the projected Burgers vector is determined to be . When imaged along the direction, the projected Burgers vector is determined to be . These misfit dislocations form a network structure at the interface to accommodate the mismatch between the lattices of the α-Fe2O3 and the α-Al2O3. 相似文献