非对称笼间电子迁移异构体与电场诱导电子迁移

基于密度泛函理论研究了非对称双笼型单分子溶剂化电子e^-@C₂₄F₂₂(NH)₂C₂₀F₁₈(1、2 和3), 进一步展示了我们提出的一种新型电子异构体——(非对称型的)笼间电子迁移异构体. 1、2 和3 具有显著不同的偶极矩. 由于都存在两个氧化还原中心, 它们属于一种非金属型的新型Robin-Day II-III 分子. 对于1 和3, 额外电子分别定域在C₂₄F₂₂和C₂₀F₁₈笼里(Robin-Day II); 对于2, 额外电子则离域于两个非对称的笼中(Robin-Day III). 值得注意的是, 在y 轴方向上外加-0.0004和-0.0008 a.u.的临界电场(E_c)时可分别使1 的额外电子从C₂₄F₂₂笼中部分和全部地迁移到C₂₀F₁₈笼中, 即实现从1 到2 再到3 的转化; 当E_c为0.0004 a.u.时, 3 的额外电子从C₂₀F₁₈笼中全部迁移到了C₂₄F₂₂笼中, 即3 未经过2 直接转化成了1.     

Data Offline Calibration for the BES-Ⅱ TOF System

Data offline calibration and reconstruction for the BES-Ⅱ TOF system are reported in this paper. After applying calibration constants to correct the measured raw data, a the resolution of 180 ps is obtained for the new TOF system. The power of charged particle identification is improved. The momentum for the 3σπ/K separation goes up to 0.93 GeV/c.     

Recent Research Progress of n-Type Conjugated Polymer Acceptors and All-Polymer Solar Cells

The active layer of all polymer solar cells(all-PSCs) is composed of a blend of a p-type conjugated polymer(p-CP) as donor and an n-type conjugated polymer(n-CP) as acceptor. All-PSCs possess the advantages of light weight, thin active layer, mechanical flexibility, low cost solution processing and high stability, but the power conversion efficiency(PCE) of the all-PSCs was limited by the poor photovoltaic performance of the n-CP acceptors before 2016. Since the report of the strategy of polymer...     

Deprotection of N-tosylated indoles and related structures using cesium carbonate

A very mild, efficient, and convenient method for deprotection of N-tosylated indoles and related structures by cesium carbonate in THF-MeOH is described.     

Syntheses and Crystal Structures of Two New Metal Phosphonates:[Mn(H_2O)_2(C_(12)H_8N_2)(HO_3PCH_2CH_2CO_2)] and [Co(H_2O)_4(C_(10)H_8N_2)]·(HO_3PCH_2CH_2CO_2)

By the reactions of manganese(II) acetate, 2-sulfoethylphosphonic acid, 1,10-phen (1,10-phen = 1, 10-phenanthroline) or cobalt(II) acetate, 4,4'-bipy and 2-carboxyethylphosphonic acid, two novel compounds of [Mn(H2O)2(C12H8N2)(HO3PCH2CH2CO2)] (1) and[Co(H2O)4 (C10H8N2)]· (HO3PCH2CH2CO2) (2) have been synthesized and characterized by IR spectroscopy, elemental analyses and single-crystal X-ray diffraction. Compound 1 has a 0D structure. Two Mn(II) ions are linked by two 2-carboxyethylphosphonic acid ligands, forming a centrosymmetric dimer. These dimers are further interlinked into a 2D layer structure by π-π stacking interactions and hydrogen bonds. Compound 2 has a 1D chain structure. The 2-carbo- xyethylphosphonic acid remains uncoor- dinated and acts as the organic template. By the bridge of 4,4'-bipy, the [Co(4,4'-bipy)]2+ chains are formed.     

BESⅡ顶点探测器

介绍了BESⅡ上正在运行的顶点探测器基本结构、特点和性能(覆盖95%×4π立体角,空间分辨σ_rφ≈100μm,σ_z≈2mm),及工作方式和电子学读出,并进一步介绍它在北京谱仪上的作用.     

BES-Ⅱ TOF数据的离线刻度

简要地讨论了北京谱仪-Ⅱ(BES-Ⅱ)飞行时间计数器(TOF)数据的离线刻度.利用J/φ能区的电子对事例仔细完成的离线刻度与校正结果表明,新的TOF时间分辨达到σ_TOF=180ps.由此大大增强了对带电粒子的识别能力.对于3σ的π/K分离其动量可以达到0.93GeV/c.     

R值扫描中积分亮度的测量

在R值扫描中利用大角度Bhabha事例测量积分亮度,较之以往的同类过程积分亮度的测量,在事例选择和探测效率的确定方面都作了较大的改进. 用不同的测量方法对本文的结果进行了检查,发现几种结果在误差范围内是一致的. 但本文的测量优化了事例选择条件,所以在一定程度上改善了系统误差.