Study of （e, 2e） process on potassium at 6 eV-60 eV above threshold in a second-order Born approximation

The standard distorted wave Born approximation(DWBA) method has been extended to second-order Born amplitude in order to describe the multiple interactions between the projectile and the atomic target.Second-order DWBA calculations have been preformed to investigate the triple differential cross sections(TDCS) of coplanar doubly symmetric(e,2e) collisions for the alkali target potassium at excess energies of 6 eV-60 eV.Compared with the previous first-order DWBA calculations,the present theoretical model improves the degree of agreement with experiments,especially for the backward scattering angle region of TDCS.This indicates that the present second-order Born term is capable of giving a reasonable correction to the DWBA model in studying coplanar symmetric(e,2e) problems in low and intermediate energy ranges.     

A density functional theory structures,stabilities, and study on size-dependent electronic properties of bimetallic MnAgm （M=Na,Li; n ＋ m ≤ 7） clusters

The equilibrium geometries, relative stabilities, and electronic properties of MnAgm（M=Na, Li; n ＋ m ≤ 7） as well as pure Agn, Nan, Lin （n ≤ 7） clusters are systematically investigated by means of the density functional theory. The optimized geometries reveal that for 2 ≤ n ≤ 7, there are significant similarities in geometry among pure Agn, Nan, and Lin clusters, and the transitions from planar to three-dimensional configurations occur at n = 7, 7, and 6, respectively. In contrast, the first three-dimensional （3D） structures are observed at n ＋ m = 5 for both NanAgm and LinAgm clusters. When n ＋ m ≥5, a striking feature is that the trigonal bipyramid becomes the main subunit of LinAgm. Furthermore, dramatic odd-even alternative behaviours are obtained in the fragmentation energies, secondorder difference energies, highest occupied and lowest unoccupied molecular orbital energy gaps, and chemical hardness for both pure and doped clusters. The analytic results exhibit that clusters with an even electronic configuration （2, 4, 6） possess the weakest chemical reactivity and more enhanced stability.     

锂离子电池正极材料Na3V2（PO4）2F3的原位XRD及固体核磁共振研究

采用溶胶凝胶法制备Na3V2（PO4）2F3/C复合材料,该材料具有优异的电化学循环性能和倍率性能.利用电化学原位同步辐射X射线衍射（XRD）及魔角旋转固体核磁共振（MASSS-NMR）技术研究了Na3V2（PO4）2F3材料充放电过程中结构变化过程及Li/Na嵌入-脱出反应.研究结果表明,Na3V2（PO4）2F3的电极反应按嵌入-脱出反应机理进行,充放电过程中材料具有优异的结构稳定性.我们还发现Na3V2（PO4）2F3与电解液接触后与电解液中的Li＋发生部分交换反应形成LixNa3-xV2（PO4）2F3.在首次充电时,Li＋和结构中Na1位置的Na＋共同从晶格中脱出;而首次放电过程中,Na＋和Li＋共同嵌入到晶格中;充放电过程中发生的是Li＋和Na＋的共嵌入-脱出反应.     

静态法和EXAFS技术研究放射性核素63^Ni（Ⅱ）在丝光沸石上的吸附机理

结合静态实验和X射线吸收精细结构光谱（EXAFS）技术研究了接触时问、离子强度、初始浓度以及共存电解质离子等水化学条件对放射性核：63^Ni（Ⅱ）在丝光沸石上的吸附行为和微观机制的影响．宏观实验结果表明：放射性核素。63^Ni（Ⅱ）在丝光沸石上的吸附在pH〈7的范围内受离子强度影响,而在pH〉7的范围内不受离子强度影响．放射性核素63^Ni（Ⅱ）在丝光沸石上的吸附率随着固体浓度的增加而升高,而对应的吸附量却随着固体浓度的增加而降低．溶液中共存的电解质离子对63^Ni（Ⅱ）在丝光沸石上的吸附有一定的促进或抑制作用,具体的影响趋势和程度由共存离子的性质、共存离子与63^Ni（Ⅱ）的络合能力以及与丝光沸石表面的亲和力大小共同决定．EXAFS微观结构分析结果表明：在pH6．5的溶液中,63^Ni（Ⅱ）与丝光沸石结构框架中的Na^＋／Ca。’等阳离子进行离子交换,形成六水合的外层络合物,不同离子强度下63^Ni（Ⅱ）的微观形态没有明显区别．郇Ni（II）在丝光沸石上的吸附随时间的变化呈现两种不同的作用机制：在溶液pH7．2的条件下,吸附初始的快速反应阶段中63^Ni（Ⅱ）的吸附主要以通过形成内层络合物的形式进行;随着接触时间的增长63^Ni（Ⅱ）在丝光沸石上的吸附机理转变为镍页硅酸盐共沉淀或者氢氧化镍沉淀的形成．初始63^Ni（Ⅱ）浓度为100mg／L的EXAFS图谱分析结果表明表面多聚体的形成是此条件下63^Ni（Ⅱ）在丝光沸石上的主要吸附机理．放射性核素63^Ni（Ⅱ）在丝光沸石／水界面的吸附行为和形态分布对于准确预测其在环境介质中的迁移转化和生物有效性等物理化学行为具有重要的意义．     

可用蓝光激发的以羧基联吡啶为桥联配体的Ir（Ⅲ）-Eu（Ⅲ）双金属配合物

本文制备了一种以羧基联吡啶为桥联配体的Ir（Ⅲ）-Eu（Ⅲ）双金属配合物,并且进行了详细的光物理性质表征.该配合物具有高的光致发光量子效率（46%）,而且Ir（Ⅲ）配合物作为天线分子对Eu（Ⅲ）离子具有很高的敏化效率（93%）.TD-DFT计算研究表明,羧基联吡啶在传能过程中起到重要作用.利用Ir（Ⅲ）配合物长波长的3MLCT吸收,可以把激发波长扩展到500nm的可见光范围.     

不同温度下烧结的Y211对YBCO的磁通俘获场的影响

采用顶部籽晶熔融织构法制备了YBCO准单畴块材,研究了在不同温度下烧结的Y2BaCuO5(Y211)粒子在块材中的分布及其对于磁通俘获场的影响.Y211前驱粉是通过使用氧化钇(Y2O3)、碳酸钡(BaCO3)、氧化铜(CuO)粉末在840到970℃之间煅烧制备.扫描电子显微镜(SEM)观察发现,通过900℃烧结的Y211颗粒在准单畴超导块材中的分布是均匀的.总的来说,使用性能好的Y211粉末将会降低Y211颗粒在块材的尺寸,提高了块材的磁通俘获场.在77K的温区下,直径为35mm的YBCO块材的磁通俘获场的最大值可以达到0.73T.     

荧光粉Y3Mg2AlSi2O12∶Ce3+的合成及光谱性能研究

采用溶胶-凝胶法合成了Y₃Mg₂AlSi₂O₁₂∶Ce³⁺荧光粉。用X射线粉晶衍射(XRD)仪对其进行了物相分析,用电子扫描电镜(SEM)观察了该荧光粉的形貌,同时测定了激发光谱及发射光谱。结果表明,Y₃Mg₂AlSi₂O₁₂∶Ce³⁺的晶体结构与Y₃Al₅O₁₂(钇铝石榴石)一致,形貌也表现出等轴粒状的特点。发射谱为峰值位于580 nm处的宽带发射,是Ce³⁺的 4f⁶5d¹-4f⁷特征跃迁发射。激发谱表现为340 nm和468 nm的双峰带,可以被蓝光有效的激发。Ce³⁺的浓度对发光强度有明显的影响,当Ce³⁺的摩尔分数为0.06时,发光强度最大。最后考察了成分取代而导致的Y₃Mg₂AlSi₂O₁₂∶Ce³⁺的物相转变和对发光性能的影响。     

Painleve Property,Beicklund Transformations and Rouge Wave Solutions of （3 ＋ 1）-Dimensional Burgers Equation

Burgers equation is the simplest one in soliton theory, which has been widely applied in almost all the physical branches. In this paper, we discuss the Painleve property of the （3＋1）-dimensional Burgers equation, and then Becklund transformation is derived according to the truncated expansion of the obtained Painleve analysis. Using the Backlund transformation, we find the rouge wave solutions to the equation via the multilinear variable separation approach. And we aiso give an exact solution obtained by general variable separation approach, which is proved to possess abundant structures.     

Gamma-ray bursts in the swift-Fermi era

Gamma-ray bursts （GRBs） are among the most violent occurrences in the universe. They are pow- erful explosions, visible to high redshift, and thought to be the signature of black hole birth. They are highly luminous events and provide excellent probes of the distant universe. GRB research has greatly advanced over the past 10 years with the results from Swift, Fermi and an active followup community. In this review we survey the interplay between these recent observations and the theoretical models of the prompt GRB emission and the subsequent afterglows.     

Frontier applications of electrostatic accelerators

Electrostatic accelerator is a powerflfl tool in many research fields, such as nuclear physics, radiation biology, material science a.rchaeology and earth sciences. Two electrostatic accelerators, one is the single stage Vail de Gi＇aaff with terminal voltage of 4.5 MV and another one is tile EN tamteIn with terminal voltage of 6 MV, were installed in 1980s and had been put into operation since the early 1990s at tile Institute of Heavy Ion Physics. Marly applications have been carried out since then. These two accelerators are described and summaries of the most important applications on neutron physics and technology, radiation biology and material science, as well as accelerator mass spectrometry （AMS） are presented.