AlmN2和AlmN+2(m=1～8)团簇结构与稳定性的量子化学研究

用密度泛函理论(DFT）的B3LYP方法，在6-311G水平上AlmN2和AlmN^ 2(m=1～8)团簇的几何构型、电子结构、振动频率和分子轨道进行了理论研究．结果表明，AlmN2类团簇的基态结构有两种基本构型，一种是以N-N键为核心周围与Al原子相配位形成的，一种是由两个AlnN(n≤m，2)分子碎片通过共用Al原子或Al—Al键相互结合形成的．对AlnN分子碎片相互结合形成结构的绝热电离能讨论得到，m为偶数的团簇比m为奇数的稳定。     

Temporal interference driven by an oscillating electric field in photodetachment of H~- ion

The real time domain interferometry for the photodetachment dynamics driven by the oscillating electric field has been studied for the first time. Both the geometry of the detached electron trajectories and the electron probability density are shown to be different from those in the photodetachment dynamics in a static electric field. The influence of the oscillating electric field on the detached electron leads to a surprisingly intricate shape of the electron waves, and multiple interfering trajectories generate complex interference patterns in the electron probability density. Using the semiclassical open-orbit theory, we calculate the interference patterns in the time-dependent electron probability density for different electric field strengths, different frequencies and phases in the oscillating electric field. This method is universal, and can be extended to study the photoionization dynamics of the atoms in the time-dependent electric field. Our study can guide the future experimental researches in the photodetachment or photoionization microscopy of negative ions and atoms in the oscillating electric field.     

新型铼系聚吡咯络合物（PPREC）结构与吸附小分子行为的研究

应用ＣＮＤＯ／２研究了铼系聚吡咯络全物的结构及吸附小分子的行为，探究了吸附过程的微观机制。优化了各个体系的几何构型，得到了稳定性与相对于能量、结合能、吸附取向、分子间距的依存关系。     

Ionic-Liquid-Gating Induced Protonation and Superconductivity in FeSe,FeSe_(0.93)S_(0.07), ZrNCl, 1T-TaS_2 and Bi_2Se_3

We report protonation in several compounds by an ionic-liquid-gating method, under optimized gating conditions.This leads to single superconducting phases for several compounds. Non-volatility of protons allows post-gating magnetization and transport measurements. The superconducting transition temperature T_c is enhanced to 43.5 K for FeSe_(0.93)S_(0.07), and 41 K for Fe Se after protonation. Superconducting transitions with T_c～15 K for ZrNCl,～7.2 K for 1-TaS_2, and ～3.8 K for Bi_2Se_3 are induced after protonation. Electric transport in protonated FeSe_(0.93)S_(0.07) confirms high-temperature superconductivity. Our~1 H nuclear magnetic resonance(NMR)measurements on protonated Fe Se_(1-x)S_x reveal enhanced spin-lattice relaxation rate 1/~1T_1 with increasing x,which is consistent with the LDA calculations that H~+ is located in the interstitial sites close to the anions.     

外延温度对YBCO薄膜结构与性能的影响

采用化学溶液沉积法(CSD),在758℃到772℃不同温度下制备了一系列YBa2Cu3Ox(YBCO)薄膜。通过X射线衍射、扫描电镜观察和物性测量,研究了外延温度对其结构与性能的影响。研究结果表明,在760℃及770℃附近存在两个适合YBCO薄膜外延生长的温度区间,在这两个温区生长制备的YBCO薄膜具有良好的超导性能。760℃和770℃附近制备的样品的临界超导转变温度Tc分别为90K和89K,说明760℃附近的较低温区更适合YBCO薄膜的外延生长。760℃附近生长的薄膜在77K自场下的临界电流密度Jc可达到3MA/cm2。文中进一步对存在两个外延温区间的现象进行了讨论,其机制可能来源于自发形核与诱导外延生长之间的相互竞争。     

高耐压和低暗计数SiC紫外雪崩光电二极管

碳化硅（SiC）雪崩光电二极管（APD）是一种独具优势的微弱紫外光探测器,其过偏压承受能力是确保器件可靠工作的一个重要因素。本工作设计并制备了穿通型SiC吸收层-电荷控制层-雪崩倍增层分离（SACM）APD。基于这种结构,器件电场从雪崩倍增层向吸收层扩展,从而减小了雪崩倍增层内电场强度变化率,最终将器件过偏压承受能力提高到10 V;得益于吸收层的分压,雪崩倍增层的电场强度得到有效降低,载流子隧穿可能性减小,这能够有效降低器件暗计数,从而有利于提高器件探测灵敏度;此外,设计的SiC SACM APD倾斜台面仅刻蚀到雪崩倍增层上表面,这能够让器件填充因子提高至约60%,显著改善了深刻蚀导致的传统SACM结构有效光敏区域减小的问题。     

Probe R-Parity Violating Supersymmetry in Forward--Backward Asymmetry

We investigate the possibility of probing R-parity violating interactions in forward-backward asymmetries, and conclude that the Tevatron collider is the best place to measure new interactions involving the first generation of quarks. With additional down type squark ~dk contributions, the charge asymmetry in e＋e— events around Z-pole mass region at the Tevatron will be sensitive to R-parity violating couplings λ’11k, which was inaccessible to the LEP Qfb had inclusive measurement. Assuming no apparent deviation from SM prediction is observed, λ’11k〈 0.19 at 95% C.L. with squark mass Mdk=100 GeV can be derived.     

几种含吡啶环的双醛腙类化合物的结构与光谱性质

采用DFT/B3LYP方法在3-21+G基组下对4种含吡啶环的双醛腙类化合物进行基态(S_0)构型优化,并用单组态相互作用方法(CIS)优化四种化合物分子的激发态(S_1)结构,从理论上探讨了四种化合物的分子轨道能量、电子吸收和发射光谱等性质与结构的关系,并与实验值进行了对比,发现理论计算数据能够与实验结果基本一致.通过对分子中前线轨道能量的计算,揭示了不同取代基对材料光电活性的影响,即分子中的共轭体系增大,吸收光谱波长也随之红移.根据化合物的吸收和发射光谱的计算数据推测化合物D是这四种化合物中最可选的电子传输材料及光活性材料.     

环己酮与丙烯酸甲酯及(S)-3-(2′-氧环己基)-丙酸与醇的酯化反应

在(R)TTCA·K催化下由环己酮直接与丙烯酸甲酯进行Michael加成反应得到了(S)-3-(2′-氧环己基)-丙酸甲酯, [α]20D-4.14(41.5% e.e.).     

浅谈珠脑速算的发展前景

珠脑速算教育是启迪智力,进行素质教育,功在当代,利在千秋的“重要工程”。它具有早期开发儿童智力,增强儿童感知力、想象力、记忆力等功能,那么这项科研项目,它的发展前景如何?成为从事这项科研的工作者