2-硅萘与甲醛及二苯甲酮环加成反应的理论研究

采用密度泛函理论(DFT)方法在B3LYP/6-311G**水平研究了2-硅萘与甲醛和二苯甲酮的[2+2]和[4+2]杂环加成反应的微观机理、势能剖面,考察取代基和苯溶剂对反应势能剖面的影响.计算结果表明,所研究反应均以协同但非同步的方式进行.羰基C原子上的苯取代基不利于反应的进行,而2-硅萘分子中Si原子上的C(CH3)3,CCl3及NH2取代基均有利于反应的进行.苯溶剂对所研究反应的势能剖面影响不大.[2+2]反应比相应的[4+2]反应容易进行,此结果与实验一致.     

Co-crystallization of Resorcin[4]arene Tetracarboxylic Acid with Triethylamine: Synthesis and Crystal Structure

Treatment of resorcin[4]arene tetracarboxylic acid 1 with triethylamine in the presence of Co(CH3COO)2·4H2O and 4,4'-bipyridine gave a co-crystallization 14-·4Et3NH+(C32H20O164-·4Et3NH+,Mr=1069.27) from ethanol and water.The compound was structurally determined by single-crystal X-ray diffraction.The crystal belongs to monoclinic,space group P21/n,with a=8.1763(18),b=12.913(3),c=28.724(7) ,β=97.574(4)o,V=3006.3(12) 3,Z=2,Dc=1.181 g/cm3,F(000)=1152,Rint=0.0275,T=293(2) K,μ=0.086 mm-1,the final R=0.0634 and wR=0.1752 for 5082 observed reflections with Ⅰ 2σ(Ⅰ).The co-crystallization is very stable at room temperature.Possibly,a network of N-H···O(=C) plays an important role in the structure.Meanwhile,the compound emits a weak cyan luminescence with peak maximum band at 458 nm.     

生成模型在蛋白质序列设计中的应用

蛋白质是一切生命体的物质基础,是生命活动的主要承担者,参与各种生理功能的调节.设计具有特定功能的蛋白质在蛋白质工程、生物医药、材料科学等领域具有重要意义.蛋白质序列设计的目标是设计能够折叠成期望结构并具有相应功能的氨基酸序列,是所有理性蛋白质工程的核心问题,具有极其重要的研究和应用潜力.随着蛋白质序列数据的指数型增长和...     

中红外组合激光场调控宽带超连续谱的产生

本文对原子在波长为2000nm、脉宽为12.5fs的中红外驱动脉冲和脉宽为1.3fs的紫外控制脉冲叠加形成的组合场中产生的高次谐波进行了研究.通过组合场驱动氦原子得到了谱宽为230eV的超连续谱.利用组合场产生的谐波比单独利用中红外脉冲产生的谐波的强度高了3个量级.对超连续谱进行滤波并调节组合场中两束激光的延迟时间,可以直接产生100as的单个脉冲.我们发现超连续谱的宽度和位置几乎不会因为驱动场和控制场强度的变化而改变,这种性质有利于从实验上获得单个宽谱阿秒脉冲.     

周期量级激光脉冲驱动下非次序双电离的三维经典系综模拟

利用三维经典系综模型研究了周期量级激光脉冲驱动的氩原子非次序双电离,所得结果表明,Ar2+离子的纵向动量分布与载波包络相位有很强的依赖关系,随载波包络相位φ的增加,具有不对称双峰结构的离子纵向动量分布重心从负动量转移到正动量,并且φ每改变π时Ar2+离子的纵向动量呈现相反的分布.在重碰撞过程中核与电子之间的库仑势发生变化后,计算得到的Ar2+离子纵向动量分布随载波包络相位的变化与实验结果定量上一致.     

Design and Application of a Near Field Microwave Antenna for the Spin Control of Nitrogen-Vacancy Centers

Controlled manipulation of the electron spin by means of a microwave field is investigated. The near magnetic field generated by a copper wire antenna is measured experimentally and simulated theoretically, and the optimum antenna length and position are obtained. By measuring the change in the fluorescence of nitrogen-vacancy （N-V） centers in diamond after excitation with a 532 nm continuous wave laser at room temperature, it is verified that the spin of the N-V center can be effectively controlled by the microwave field.     

四-(叔丁基)-四氮杂卟啉金属配合物的振动光谱和DFT计算

测量了四-(叔丁基)-四氮杂卟啉金属配合物(MT(tBu)TAP,M=Cu, Co, Ni, Zn)的拉曼和红外光谱. 在B3LYP理论水平上计算了其基态结构和振动光谱,基于计算结果对观察到的拉曼谱带进行了详细的指认. 考察了拉曼和红外谱带频率变化与四氮杂卟啉环结构的关系. 随着环内核尺寸的减小,C_βC_β′伸缩振动(A_g)、C_αN_m反对称伸缩振动(A_g)、以及C_αN_m对称伸缩振动(B_g) 的频率线性地增加,其中后两者对环内核尺寸的变化更为敏感.     

37-element solar adaptive optics for 26-cm solar fine structure telescope at Yunnan Astronomical Observatory

A 37-element solar adaptive optics （AO） system was built and installed at the 26-cm solar fine structure telescope of Yunnan Astronomical Observatory. The AO system is composed of a fine tracking loop with a tip/tilt mirror and a correlation tracker, a high-order correction loop with a 37-element deformable mirror, a correlating Shack-Hartmann wavefront sensor based on the absolute difference algorithm, and a real time controller. The system was completed on Sep. 28, 2009 and was used to obtain AO-corrected high-resolution solar images. The contrast and resolution of the images are clearly improved after wavefront correction by AO. To the best of out knowledge, this system is the first solar AO system in China.     

Resonance Raman Study of Aggregated Meso-tetra(4-pyridinium) porphyrin Diacid

研究了近激子吸收带激发下四-(4-吡啶基)卟啉二酸(H₈TPyP⁶⁺)聚集体的共振拉曼光谱．测量了H₈TPyP⁶⁺单体和聚集体的紫外可见吸收谱和共振光散射光谱．在氘代位移的基础上结合相关体系振动光谱研究,对测得的H₈TPyP⁶⁺)单体和聚集体的拉曼谱带进行了指认．聚集体的形成导致H₈TPyP⁶⁺的卟啉环CC/CN面内伸缩振动向低波数方向位移2～6 cm^-1,而卟啉环鞍形面外振动带向高波数方向位移12cm^-1．基于拉曼谱带的强度和频率变化分析了聚集引起的H₈TPyP⁶⁺分子内结构变化和分子间氢键作用     

Structure change of 156Yb at high-spin states

High-spin states of ¹⁵⁶Yb have been studied via the ¹⁴⁴Sm(¹⁶O,4n)¹⁵⁶Yb fusion-evaporation reaction at beam energy 102~MeV. The positive-parity yrast band and negative-parity cascade have been extended up to higher-spin states, respectively. The characteristics of the negative-parity sequence above the 25^－ state may related to the excitation from the nucleon in the Z=64, N=82 core. The E-GOS curve for the positive-parity yrast sequence in ¹⁵⁶Yb indicate that this nucleus may undergo an evolution from quasivibrational to quasirotational structure with increasing angular momentum. The Cranked Woods-Saxon-Strutinsky calculations by means of Total-Routhian-Surface (TRS) methods has been made to understand this structure change.