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The collison-induced reaction of Na^ ion with neutral C60 vapour was investigated at the energy range of 10 to 150eV.The deposited films were studied via laser desorption time-of-flight mass spectroscopy(TOFMS).The fragment products of C60 with even number of carbon atoms,such as Cn^ (n=58,56,54),and adduct products,such as Cn^ (n=62,64,66,68) were observed in the positively charged TOF mass spectra.The endohedral fullerene ion of Na @C60^ was detected when collision energies are above 20eV.Besides,no negative endohedral fullerene was detected,the products appearing in positively charged mass spectra were also observed in the negatively charged mass spectra.In addidtion,a series of products with odd number of carbon atoms,such as Cn^-(n=53,55,57,59,61,63,65,67),also appeared.but the intensities of their signals were not as high as that of even numbered.Finally,it is interesting to find that the deposited films are insoluable in toluene,benzene or water.Their Fourier transform infrared (FTIR),spectra seem like those photopolymerized ones.Some of the reaction schemes are proposed to explain the experimental results. 相似文献
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《核技术(英文版)》2018,(11)
Abstract The effects of mass asymmetry on the production of superheavy nuclei(SHN),within the dinuclear system model,are investigated in this study.It is observed that the fusion probability decreases with decreasing mass asymmetry.A total of 192 possible combinations of projectiles from O to Ti and targets with half-lives longer than30 days for producing SHN~(264)Db,~(265)Db,~(267)Sg,~(268)Bh,268Sg,~(269)Bh,~(271)Hs,~(271)Mt,~(272)Hs,~(272)Mt,~(273)Mt,~(274)Ds,275Ds,~(275)Rg,~(276)Ds,~(276)Rg,~(277)Rg,~(278)Cn,~(279)Cn,and~(280)Cn are examined.Further,the optimal combinations and incident energies for synthesizing these nuclei are predicted.Most of the cross sections for production of SHNare larger than 10 pb;therefore,the process can be carried out with the available experimental equipment. 相似文献
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强脉冲离子注入中的脉冲能量效应研究 总被引:4,自引:0,他引:4
在脉冲离子束流密度为15120A/cm2、脉宽为50150ns、加速电压为150260kV范围内,在11014cm-2的低注量水平上, 研究了高功率Cn++H+混合离子束注入45号钢样品的强脉冲能量效应。摩擦磨损和微观硬度测量以及SEM和X射线衍射分析表明,上述低注量强脉冲离子束注入可以改变材料 表面的微观结构和力学特性,而且强烈依赖于单个脉冲离子束的功率密度和能量密度。在相同离子注量条件下,普通C++H+离子注入对45号钢样品表面微硬度和摩擦系数未 见明显影响。直接证明了强脉冲能量效应在离子注入中是相对独立于注入元素掺杂效应的又一可利用的重要效应。基于一维导热模型,讨论了强脉冲能量效应以及脉冲离 子束功率密度对离子束材料表面改性的作用。 相似文献
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用增长率方法首次测量6-30keVB^+、C^+、N^+、O^+与H2碰撞的单了截面,给出的B^+和C^+和6-30keV能区截面随离子能量的趋势与已有的100-2500keV能区截面的变化趋势衔接很好。根据截面随入射离子能量和核电荷数的变化,对碰撞机理作了分析,B^+、N^+、O^+与H2碰撞的单电子剥离截面的变化规律由分子轨道模型得到很好的解释。 相似文献
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A. Meldrum L. A. Boatner W. J. Weber R. C. Ewing 《Journal of Nuclear Materials》2002,300(2-3):242-254
Single crystals of the ABO3 phases CaTiO3, SrTiO3, BaTiO3, LiNbO3, KNbO3, LiTaO3, and KTaO3 were irradiated by 800 keV Kr+, Xe+, or Ne+ ions over the temperature range from 20 to 1100 K. The critical amorphization temperature, Tc, above which radiation-induced amorphization does not occur varied from approximately 450 K for the titanate compositions to more than 850 K for the tantalates. While the absolute ranking of increasing critical amorphization temperatures could not be explained by any simple physical parameter associated with the ABO3 oxides, within each chemical group defined by the B-site cation (i.e., within the titanates, niobates, and tantalates), Tc tends to increase with increasing mass of the A-site cation. Tc was lower for the Ne+ irradiations as compared to Kr+, but it was approximately the same for the irradiations with Kr+ or Xe+. Thermal recrystallization experiments were performed on the ion-beam-amorphized thin sections in situ in the transmission electron microscope (TEM). In the high vacuum environment of the microscope, the titanates recrystallized epitaxially from the thick areas of the TEM specimens at temperatures of 800–850 K. The niobates and tantalates did not recrystallize epitaxially, but instead, new crystals nucleated and grew in the amorphous region in the temperature range 825–925 K. These new crystallites apparently retain some ‘memory' of the original crystal orientation prior to ion-beam amorphization. 相似文献
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采用基于协变密度泛函理论的含时生成坐标方法研究了258Fm低能诱发裂变动力学性质,重点探讨了裂变位能曲面、裂变碎片总动能分布和碎片质量分布等。研究表明,258Fm位能曲面中存在显著的对称裂变谷,因而其低能裂变碎片总动能分布与质量分布均呈单峰结构,且随剪裂线判据Qn(脖子处粒子数)从4减至1,碎片总动能分布变窄,碎片质量分布的峰值从988%增至1028%。此外,随初态激发能从83 MeV增至173 MeV,碎片质量分布峰值从988%降至855%。 相似文献
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A new version of improved quantum molecular dynamics model that includes standard Skyrme interactions has been developed. Based on the new code, four commonly used parameter sets, SLy4, Ski2, SkM* and Gs are adopted in the improved quantum molecular dynamics model and the isospin sensitive observables, namely isospin transport ratios, single and double ratios of the yields of neutrons and protons are investigated. The isospin transport ratios are strongly sensitive to the slope of symmetry energy, and are not very sensitive to the nucleon effective mass splitting. On the other hand, the high energy neutrons and protons yields ratios from reactions at different incident energies provide a good observable to the momentum dependence of nucleon effective mass splitting. By comparing our calculations with the data, we find that the constrained L value (the slope of density dependence of symmetry energy) is about -46 MeV when the Skyrme type interaction is considered in transport models, and the isospin diffusion data prefer to mn 〉 mp, but it is not a strong constraint with deep Z2 minimum. 相似文献
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The symmetry energy at the time of the production of intermediate mass fragments (IMFs) is studied using experimentally observed IMF multiplicities combined with quantum statistical model calculations (QSM of Hahn and Stfcker). The ratios of difference in chemical potentials between neutrons and protons relative to the temperature,(μt- μp) /T, and the double ratio temperature, T, were extracted experimentally in the reactions of 64'7~Zn, 64Ni+58'64Ni, 112'124Sn, 197Au, 232Th at 40A MeV. The extracted (μt- μp) / T scales linearly with Jwv, where fi~v is the asymmetry parameter, (N-Z)/A, of the emitting source and (μt- μp) / T = (11.1 + 1.4)rNN -- 0.21 was derived. The experimentally extracted (μt-μp)/T and the double ratio temperatures are compared with those from the QSM calculations. The temperatures, T, and densities, p, extracted from the (μn - μp) / T values agreed with those from the double ratio thermometer which used the yield ratios of d, t, h and a particles. However the two analyses of the differential chemical potential analysis and the initial temperature analysis end up almost identical relation between T and p. T=5.25±0.75 MeV is evaluated from the (μn -μp) / T analysis, but no density determination was possible. From the extracted T value, the symmetry energy coefficient Esym=14.6±3.5 MeV is determined for the emitting source of T=5.25±0.75 MeV. 相似文献
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微波煅烧重铀酸铵制备U3O8工艺研究 总被引:2,自引:0,他引:2
基于重铀酸铵在微波场中的升温特性,研究了微波煅烧重铀酸铵制备八氧化三铀的新工艺。探讨了微波功率、微波加热时间及物料量等因素对八氧化三铀产品中总铀和U4+含量的影响规律。研究结果表明,微波功率和微波加热时间对八氧化三铀产品中总铀和U4+含量的影响显著。在本实验范围内,微波煅烧重铀酸铵制备八氧化三铀的最佳工艺条件为:微波功率700 W,微波加热时间10min,物料量60g。在最佳工艺条件下,八氧化三铀产品中总铀和U4+含量分别为84.62%和28.74%,其产品质量满足后续工序要求。微波煅烧重铀酸铵制备八氧化三铀是可行的。 相似文献
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基于三维朗之万模型对低能核裂变动力学过程和断点构型进行了研究,其中位能曲面采用基于双中心壳模型和有限程液滴模型的宏观 微观模型计算得到,质量张量和黏滞张量分别采用Werner Wheeler方法和墙加窗一体模型得到。以14 MeV中子诱发235U裂变为例,分别研究了拉长形变空间和壳衰减因子对裂变碎片质量分布、总动能分布及断点处核拉长与质量非对称度关联的影响,确定了模型计算中拉长形变空间边界至少应为35R0(R0为球形核半径),以及壳衰减因子的合理取值为60 MeV。基于该模型,计算得到了14 MeV中子诱发233,235U裂变碎片质量分布,与ENDF/B Ⅷ0评价数据符合较好,说明该模型具有定量计算裂变碎片质量分布的能力。 相似文献
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采用三重四级杆质谱模拟并分析微观含铀分子化学键断裂形成新的物质的过程以探讨单质铀的产生机理。结果表明,含铀分子在质谱中离子化后经碰撞诱导解离可生成U+。研究还发现,硝酸铀酰溶液通过电喷雾可形成UO+2(m/z 270)、UO2OH+(m/z 287)、UO2H2OOH+(m/z 305)、UO2NO+3(m/z 332)、UO2(H2O)3NO+3(m/z 386)及双聚铀酰离子[(UO2NO3H2O)2NO3]+(m/z 762),在具有一定动能N2的碰撞下它们均可产生游离的U+。通过模拟实验推测,天然单质铀形成的微观机理为:在漫长地质年代中放射性核素持续衰变产生的能量粒子撞击含铀分子使其化学键断裂生成游离铀离子,在封闭或强还原性等特殊地质条件下形成单质铀并被保存下来。 相似文献
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Kan Ashida Masao Matsuyama Kuniaki Watanabe Hiroshi Kawamura Etsuo Ishitsuka 《Journal of Nuclear Materials》1994,210(3):233-238
With respect to the impurity emission and erosion of a Be first wall, a secondary ion mass spectrometric investigation was carried out along with surface characterization with X-ray photoelectron spectroscopy. It was found that Be is emitted as distinct types of chemical forms from the surface owing to sputtering with Ar+ and an (Ar++ D+2) mixture: (i) Be and Be-cluster, (ii) oxide and hydroxide, and (iii) hydride and/or deuteride. 相似文献
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Dependence of decamethylcyclopentasiloxane (DMCPS) organosilicon dissociation on ionized energy in the energy range of 25 to 70 eV is investigated by using a quadrupole mass spectrometry. At the ionized energy below 55 eV, the dissociation of DMCPS is dominant. As the ionized energy is above 55 eV, the DMCPS dissociation achieves the maximum cross section, while the fragments from the DMCPS dissociation can further dissociate, which leads to a different ingredient of fragments. At the lower ionized energy of 25 eV, the main fragments are SiOC2H5+, SiCH+, Si+, O2+ and CH3+ ions, which shows an important effect on the SiCOH low-k film deposition. 相似文献
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Mitsumasa TAGUCHI Takuji KOJIMA 《核技术(英文版)》2007,18(1):35-38
Dependence of yields of OH (hydroxyl) radicals on the mass and specific energy of heavy ions and elapsed time after irradiation was investigated, to understand chemical reactions of aqueous solutions. The yields of irradiation products of phenol, super-linearly increased with the incident energy of He, C, and Ne ions ranging from 2 to 18 MeV/u. The yields of the OH radicals were estimated by analyzing the yields of the irradiation products of phenol. The yields of the OH radicals increased with the specific energy for each ion, but decreased both with the mass of each ion at the same specific energy and elapsed time after irradiation. 相似文献
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Heat transfer and fluid flow in a molten pool are influenced by internal volumetric heat generated from the radioactive decay of fission product species retained in the reactor vessel during a severe accident. The pool superheat is determined based on the overall energy balance that equates the heat production rate to the heat loss rate. Decay heat of fission products in the pool is estimated by product of the mass concentration and energy conversion factor of each fission product. Twenty-nine elements are chosen and classified by their chemical properties to calculate heat generation rate in the pool. The mass concentration of a fission product is obtained from released fraction and the tabular output of the ORIGEN 2 code. The initial core and pool inventories at each time can also be estimated using ORIGEN 2. The released fraction of each fission product is calculated based on the bubble dynamics and mass transport. Numerical analysis is performed for heat and fission product transport in a molten core material pool during the Three Mile Island Unit 2 (TMI-2) accident. The pool is assumed to be a partially filled hemisphere, whose change in geometry is neglected during the numerical calculation. Calculated results indicate that the peak temperature in the molten pool is significantly lowered, since a substantial amount of the volatile fission products is released from the molten pool during progression of the accident. The results may directly be applied to the existing severe accident analysis codes to more mechanistically determine the thermal load to the reactor vessel lower head during the in-vessel retention. 相似文献
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The equation of state of symmetric nuclear matter is studied with an equivalent mass model. The equivalent mass of a nucleon has been expanded to order 4 in density. We first determine the first-order expansion coefficient in the quantum hadron dynamics, then calculate the coefficients of the second to fourth order for the given binding energy and incompressibility at the normal nuclear saturation density. It is found that there appears a density isomeric state if the incompressibility is smaller than a critical value. The model dependence of the conclusion has also been checked by varying the first-order coefficient. 相似文献