84 resultados para 18-178


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利用152Sm(31P,5nγ)178Ir反应产生并研究了双奇核178Ir的高自旋态.实验中进行了178Ir核的在束 γ测量,包括γ射线的激发函数测量、X-γ和γ-γ符合测量.首次建立了双奇核178Ir基于πh9/2νi13/2和πh11/2νi13/2准粒子组态上的转动带能级纲图.发现在低自旋区,两个转动带能级均出现旋称反转.对此核区半退耦带的旋称反转作了简要的分析和讨论.

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用阈探测器活化法测量了每个核子动能(简称单核能)为50MeV18O离子轰击厚靶(Be、Cu、 Au)时出射中子的能量分布、注量率分布和中子角分布,得到了18O离子的中子产额、前向中子发射率和中子剂量当量率分布的数据。并与国外报道的单核能在20MeV 以下的低能重离子轰击厚靶研究中得到的中子剂量学参数进行了比较和分析。

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Single-electron capture in 14 keV q(-1) Ar15+...18++He collisions is investigated both experimentally and theoretically. Partial cross sections and projectile scattering angle dependencies have been deduced from the target ion recoil momenta measured by the COLTRIMS technique. The comparison with close-coupling results obtained from a two-centre extension of the basis generator method yields good overall agreement, demonstrating the applicability of close-coupling calculations to collision systems involving highly charged ions in charge states up to 18+.

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A thick natural uranium target was bombarded with a 60 MeV/u O-18 beam. The neutron-rich isotope Ra-230 as the target residue was produced through the multinucleon transfer reaction (U-238-4p-4n). The barium and radium fraction as BaCl2 precipitate were radiochemically separated first from the mixture of uranium and reaction products. Then, the radium fraction was separated from BaCl2 precipitate by using cation exchange technique. The gamma-ray spectra of the Ra fraction were measured using an HPGe detector. The production cross sections of Ra-230 were obtained by a combination of the radiochemical separation technique and off-line gamma-ray spectroscopy. The cross section of Ra-230 has been determined to be 66 +/- 20 mu b.

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The neutron-rich target-like isotope Th-236 has been produced in the U-238-2p multinucleon transfer reaction between a 60 MeV/u O-18 beam and natural U-238 targets. The activities of thorium were determined after radiochemical separation of Th from the mixture of uranium and reaction products. The Th-236 isotope was identified by the characteristic gamma-rays of 642.2, 687.6 and 229.6 keV. The production cross section of Th-236 was determined to be 250 +/- 50 mu b.

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The gamma rays following the beta(+)/EC decay of Ir-176,Ir-178 nuclei have been investigated using in-beam gamma-ray experiment. In addition, with the aid of a helium-jet recoil fast tape transport system, the beta(+)/EC decay of Ir-176 was further studied, the new gamma rays were proved and a low-spin isomer was proposed in Ir-176. The isomeric state was analysized according to the systematics in neighboring nuclei.

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The neutron-rich target-like isotope Th-236 was produced in U-238-2p multinucleon transfer reaction between a 60MeV/u O-18 beam and nature U-238 targets. The thorium activities were radiochemically separated from the mixture of uranium and reaction products. The isotope Th-236 was identified by 642.2keV, 687.6keV and 229.6keV characteristic gamma-rays. The production cross section of Th-236 has been determined to be 250 +/- 50 mu b.

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A series of experiments have been performed by complete kinematics measurements to study two-proton (2p) correlated emission from the excited states of Ne-17,Ne-18 and S-28,S-29 via the Coulomb excitation by bombarding on Au-197 target. 2p and residua coincident events were picked Out under strict conditions. Visible p-p correlations were observed. It is shown that 2p can be emitted from the high-lying excited states. 2p halo may lead to 2p emission with large spectroscopy factor for the states close to or beyond the threshold.

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Two-electron-one-photon (TEOP) M1 and E2 transition energies, line strengths and transition probabilities between the states of the 2p(3) and 2s(2)2p odd configurations for B-like ions with 18 <= Z <= 92 have been calculated using the GRASP2K package based on the multiconfiguration Dirac-Hartree-Fock (MCDHF) method. Employing active-space techniques to expand the configuration list, we have systematically considered the valence, core-valence and core-core electron correlation effects. Breit interaction and quantum electrodynamical (QED) effects were also included to correct atomic state wavefunctions and the corresponding energies. Influences of electron correlation, Breit interaction and QED effects on transition energies and line strengths of the TEOP M1 and E2 transitions were analysed in detail. The present results were also compared with other theoretical and experimental values.

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The novel (E,E)-dioxime, 5,6:17,18-dibenzo-11,12-(4-nitrobenzo)-2,3-bis(hydroxyimino)-7,16-dithia-10,13-dioxa-1,4-diazacyclooctadecane) (H2L), has been synthesized from reaction of (E,E)-dichloroglyoxime (1) with 2,3:14,15-dibenzo 8,9-(4-nitrobenzo)-4,13-dithia-7,10-dioxa-1,16-diazahegzadecane (2). The mononuclear Co(III) complex (4) of this dioxime was prepared by oxidation of the cobalt (II) complex. The -capped Co(III) complex (5) was synthesized by using a precursor Co(III) complex and boron trifluoride dietherate. The heterotrinuclear complexes (6) and (7) were prepared by reaction of (5) with NiCl2·6H2O and CdCl2·H2O, respectively. In addition, the homotrinuclear Cu(II) complex (8), has also been prepared by the reaction of this dioxime with CuCl2·H2O. The structures of the dioxime and its complexes were identified by using elemental analysis, 1H- and 13C-NMR, IR, and mass spectral data.

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The reaction mechanism of the Beckmann rearrangement over B2O3/gamma-Al2O3 and TS-1 in the gas phase has been investigated by isotope labeling approach. The isotopic labeled products were measured by mass spectrometry method. By exchanging oxygen with H, 180 in the rearrangement step, it was found that the exchange reaction between cyclohexanone oxime and (H2O)-O-18 over B2O3/-gamma-Al2O3 and TS-1 could only be carried out in some extent. It suggested that the dissociation of nitrilium, over solid acids be not completely free as the classical mechanism. A concept of the dissociation degree (alpha) that is defined as the ratio of the dissociated intermediate nitrilium to the total intermediate nitrilium has been proposed. By fitting the experimental values with the calculation equation of isotopic labeled products, it is obtained that a values for B2O3/-gamma-Al2O3 and TS-1 are 0.199 and 0.806 at the reaction conditions, respectively.

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Well-ordered nanostructured polymeric supramolecular thin films were fabricated from the supramolecular assembly of poly(styrene-block-4-vinylpyridine) (PS-b-P4VP)(H+) and poly(methyl methacrylate)-dibenzo-18-crown-6-poly(methyl methacrylate) (PMCMA). A depression Of cylindrical nanodomains was formed by the block of P4VP(H+) and PMCMA associates surrounded by PS. The repulsive force aroused from the incompatibility between the block of P4VP(H+) and PMCMA was varied through changing the molecule weight (M-w) of PMCMA, the volume fraction of the block of P4VP(H+), and annealing the film at high temperature. Increasing the repulsive force led to a change of overall morphology from ordered nanoporous to featureless structures. The effects of solvent nature and evaporation rate on the film morphology were also investigated. Further evolution of surface morphologies from nanoporous to featureless to nanoporous structures was observed upon exposure to carbon bisulfide vapors for different treatment periods. The wettability of the film surface was changed from hydrophilicity to hydrophobicity due to the changes of the film surface microscopic composition.

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以Dawson型砷钼酸、金刚烷胺为原料 ,合成了一个新的超分子化合物 :(C10 H18N) 6As2 Mo18O62 ·6CH3 CN·8H2 O .通过元素分析 ,IR ,1HNMR等方法对合成的化合物进行了表征 .X射线衍射晶体解析表明 ,金刚烷胺与Dawson型多阴离子以静电力和分子间力 (氢键 )结合 ,并且在新化合物中 ,金刚烷胺及多阴离子结构基本保持不变 .该化合物均具有可逆的光致变色特性 ,基于变色后样品的电子自旋共振 (ESR)谱提出一个可能变色机理 .以该类化合物为修饰剂的本体修饰碳糊电极(APM CPE)对过氧化氢还原有很好的电催化活性.