Properties of proton-rich nuclei in a three-body model

Using a three-body model and realistic two-body potentials, we investigate the properties of the nuclei ¹⁸Ne and ²⁸S near the proton dripline. We figure out the two-proton separation energies, occupation of the valence protons, root-mean-square radii of matter and the valence protons. Besides, the spatial correlation densities are displayed to reflect the correlation between the two valence protons. The first excited 0⁺ state of ¹⁸Ne is most likely to be a halo state according to our calculation. Turning off the Coulomb interactions among the three-body systems, we get the two-neutron separation energies and configuration of the valence neutrons of their corresponding mirror nuclei. The results indicate that the three-body model is proper to describe some proton-rich nuclei and can be used to deduce reliable information.     

质子转移反应质谱在线检测痕量挥发性有机物

质子转移反应质谱是近年来兴起的一种痕量挥发性有机物在线检测技术,它可以在秒量级的时间内获得ppt量级的探测灵敏度,已经广泛的应用在环境污染监测、医学诊断、食品成分和质量检验等领域。本文介绍了它的工作原理和装置结构,给出了一些痕量挥发性有机物检测的例子,以及作者实验室使用该技术检测挥发性有机物的初步研究结果,并对该在线检测技术的发展方向进行了展望。     

Template-assisted assembly: scanning tunneling microscopy study of solvent-dependent adlattices of alkyl-derivatized tetrathiafulvalene

The self-assembly of an adsorbate as a function of the strength of solvent-substrate adsorption is an important yet relatively unexplored subject. In this study, how the strength of solvent-substrate adsorption and solvent-solvent attraction affects the assembly of tetrakis(octadecylthio)tetrathiafulvalene (1) is scrutinized by scanning tunneling microscopy (STM). For solvents with strong intermolecular interactions and adsorption onto graphite, such as long n-alkanes (C(n)H(2n+2), n ≥ 13), STM reveals that the solvent molecules form lamellae which become a template to direct the assembly of 1 into one-dimensional arrays. The lengths of one of the unit cell vectors for the assemblies are increased and well correlated with the solvent sizes. In situ STM monitoring of 1 introduced onto graphite with preadsorbed n-tetradecane adlattices shows that the developed assemblies of 1 have striped features aligned parallel to the underlying template. In contrast, for solvents with weak adsorption, such as short n-alkanes (C(n)H(2n+2), n ≤ 12), toluene, and 1,2,4-trichlorobenzene, the adlattice structures of 1 are solvent-independent.     

甘氨酸色氨酸寡肽链的红外光谱的密度泛函研究

运用密度泛函理论, 在6-31 G(d) 基组水平上对甘氨酸色氨酸交替组成的六种寡肽链结构进行几何优化, 并进行了结合能和振动光谱地分析. 结果表明, 寡肽的生长利于结构的稳定性. 随着肽链的生长, 单一基团的振动存在蓝移或奇偶震荡现象; 同类官能团的耦合振动存在红移现象; 而肽链端部基团的振动频率基本不变. 这些丰富的频移现象和尺寸效应、耦合效应、诱导效应、奇偶效应等因素共同竞争有关. 该结果对应用红外光谱对寡肽链的残基数及长度地测量等工作有指导意义. 关键词： 寡肽链 红外光谱 耦合效应 尺寸效应     

Mass spectral studies of some π-benzoylcyclopentadienylmanganese tricarbonyl derivatives

The loss of three CO groups from derivatives of π-C₆H₅COC₅H₄Mn(CO)₃ is a two-step mechanism in which the loss of two CO groups is followed by a third. Subsequent fragmentations generally involve rearrangement processes which often result in ring closure within the organic substrate. The central metal atoms plays an important part in such rearrangement processes and the positive charge can reside either on the metal or the ligand depending on the nature of the ligand. Fragmentation patterns are proposed for these systems.     

金属硫蛋白加质子常数及与Cd(II)络合常数测定

用pH计和Cd离子选择电极测定了金属硫蛋白的加质子常数及其与Cd(Ⅱ)的络合常数, 用改进的简化络合模型处理实验结果, 得到了去金属硫蛋白(apo MT)中6类不同的加质子基团的数目及其加质子常数。对Cd(Ⅱ)滴定数据的计算表明, MT中两个结构域——α和β对Cd(Ⅱ)的络合常数相差约1000倍。从热力学定量描述了MT中两个结构域结合金属离子选择优先顺序。     

高压下LiF和NaF的结构稳定性及其电子和光学性质的第一性原理研究

基于密度泛函理论，采用全势线性缀加平面波加局域轨道方法，计算模拟了LiF高压下的相变行为，预测其在450GPa附近发生由NaCl结构(B1)到CsCl结构(B2)的结构相变.同时还计算了高压下LiF不同相的电学特性，LiF的复介电函数以及介电常数随压强变化关系.通过比较能带结构的变化行为，得出LiF在53GPa附近还存在等结构相变，即由直接带隙结构变为间接带隙结构.将LiF的计算结果与另外一个同构化合物NaF进行了比较讨论. 关键词： LiF 压致相变 从头计算     

High resolution feshbach spectroscopy of cesium

We measure high-resolution Feshbach resonance spectra for ultracold cesium atoms colliding in different hyperfine and magnetic sublevels. More than 25 resonances are observed for magnetic fields up to 230 G and their positions are measured with an accuracy down to 0.03 G. From these spectra several ground-state molecular interaction parameters can be extracted with sufficient accuracy to permit for the first time an unambiguous and accurate determination of cesium's ultracold collision properties [P. J. Leo, C. J. Williams, and P. S. Julienne, following Letter, Phys. Rev. Lett. 85, 2721 (2000)].     

Surfactant-assisted synthesis of Ag nanostructures and their self-assembled films on copper and aluminum substrate

In this paper, silver nanostructures with controlled morphologies, such as plates, rods, belts, sheets and their self-assembled films have been prepared on copper and aluminum substrates by a surfactant-assisted colloidal chemical method. The X-ray powder diffraction (XRD) and the selected area electron diffraction (SAED) patterns indicated that the Ag nanostructures grew on the substrates with cubic symmetry and single-crystalline in nature. An oriented attachment with surfactant-assisted mechanism and a cooperative effect of surfactant and chloride ion on the morphology of Ag nanostructures were investigated systematically and synthetically.