Inelastic Cotunneling Current and Shot Noise of an Interacting Quantum Dot with Ferromagnetic Correlations

We explore inelastic cotunneling through a strongly Coulomb-blockaded quantum dot attached to two ferromagnetic leads in the weak coupling limit using a generic quantum Langevin equation approach. We first develop a Bloch-type equation microscopically to describe the cotunneling-induced spin relaxation dynamics, and then develop explicit analytical expressions for the local magnetization, current, and its fluctuations. On this basis, we predict a novel zero-bias anomaly of the differential conductance in the absence of a magnetic field for the anti-parallel configuration, and asymmetric peak splitting in a magnetic field. Also, for the same system with large polarization, we find a negative zero-frequency differential shot noise in the low positive bias-voltage region. All these effects are ascribed to rapid spin-reversal due to underlying spin-flip cotunneling.     

C+注入a-SiNx：H薄膜的微结构及光发射的研究

常温下对低压化学气相沉积制备的纳米硅镶嵌结构的a-SiN_x:H薄膜进行低能量高剂量的C⁺注入后,在800~1200℃高温进行常规退火处理。X射线光电子能谱(XPS)及X射线光电子衍射(XRD)等实验结果表明,当退火温度由800℃升高到1200℃后,薄膜部分结构由SiC_xN_y转变成SiN_x和SiC的混合结构。低温下利用真空紫外光激发,获得分别来自于SiN_x、SiC_xN_y、SiC的,位于2.95,2.58,2.29 eV的光致发光光谱。随着退火温度的升高,薄膜的结构发生了变化,发光光谱也有相应的改变。     

改性ZSM-5分子筛催化合成乙酸戊酯

以ZSM-5为原料,采用浸渍法将其交换成HZSM-5,以HZSM-5为催化剂,对以冰乙酸和正戊醇为原料合成乙酸戊酯的反应条件进行了研究。研究表明,以1.0m ol/L硫酸浸渍后的ZSM-5催化活性最高,当醇酸摩尔比为1.1∶1,催化剂用量为0.4g,反应时间为90m in,反应温度为125—135℃,酯化率可达82.5%。     

浊点萃取-分光光度法测定茶叶中的痕量锌

以双硫腙为显色剂,利用浊点萃取-分光光度法测定茶叶中的痕量锌在pH4.6的醋酸-醋酸钠缓冲溶液中,Zn2+与双硫腙形成稳定配合物,其λmax=528nm,方法的线性范围0.2-1.0μg·mL-1,回收率96.50％-102.50％.结果表明,该法可用于茶叶中痕量锌的测定.     

新的Schiff碱-双(2,3-二甲氧基苯甲醛)缩联苯胺的合成与光谱研究

以2,3-二甲氧基苯甲醛和联苯胺为原料,在无水甲醇溶剂中合成了一种新的Schiff碱,收率为86.0%.反应的最佳条件是2,3-二甲氧基苯甲醛与联苯胺的比例为3:1,反应时间为1h,反应温度为30℃.这种新的Schiff碱结构利用IR和UV光谱表征.     

光谱法研究α-萘乙酸与核酸的相互作用

利用荧光光谱法研究了α-萘乙酸（NAA）与DNA之间的相互作用。结果表明,DNA能使NAA的荧光强度猝灭,根据荧光强度变化和荧光猝灭公式求得NAA与DNA的荧光猝灭常数。荧光寿命实验结果表明,荧光猝灭是由形成复合物的静态猝灭过程所致。黏度实验、离子强度实验等多种实验结果表明,NAA与DNA间的结合作用为部分插入式和沟槽式相结合。     

1,3-双(1-苯基-1H-四唑-5-巯基)-乙酰苯腙钳形受体对卤素阴离子的识别机理

采用密度泛函B3LYP(Becke, three-parameter, Lee-Yang-Parr)和HF(Hatree-Fock)方法, 从理论上探讨了1,3-双(1-苯基-1H-四唑-5-巯基)-乙酰苯腙(DAPHZ)钳形受体对卤素阴离子的识别机理,结果发现DAPHZ受体以其钳形结构中的-N-H基团与卤素阴离子间形成双侧红移氢键进行识别. 经BSSE校正后DAPHZ•••F-, DAPHZ•••Cl-和DAPHZ•••Br-体系的分子识别相互作用能ΔECP分别为-327.5,-163.5和-148.3 kJmol-1, 说明钳形DAPHZ受体对F-具有最好的识别能力. 此外, 采用自然键轨道(NBO)计算, 相关H原子化学位移计算及分子中原子(AIM)等理论分析了识别体系中红移氢键的电子结构和性质, 结果表明APHZ受体对卤素阴离子的识别能力的相对顺序为DAPHZ•••F- >> DAPHZ•••Cl- ≈ DAPHZ•••Br-.     

A study of the active thermal control for the high energy detector on the HXMT

A thermal control system (TCS) based on the resistance heating method is designed for the High Energy Detector (HED) on the Hard X-ray Modulation Telescope (HXMT). The ground-based experiments of the active thermal control for the HED with the TCS are performed in the ambient temperature range from -15 to 20 ℃ by utilizing the pulse width to monitor the interior temperature of a NaI(Tl) crystal. Experimental results show that the NaI(Tl) crystal's interior temperature is from 17.4 to 21.7 ℃ when the temperature of the PMT shell is controlled within (20±3) ℃ with the TCS in the interesting temperature range, and the energy resolution of the HED is maintained at 16.2% @ 122 keV, only a little worse than that of 16.0% obtained at 20 ℃. The average power consumption of the TCS for the HED with a low-emissivity shell is about 4.3 W, which is consistent with the simulation.     

溶胶凝胶法制备Ti1-xFexO2纳米颗粒及磁性能研究

采用溶胶凝胶法制备了稀磁半导体Ti1-xFexO2(x=0～0.050)的纳米颗粒,在氩气氛围中以500℃对样品进行退火处理,并通过差热/热重综合热分析仪(TG-DTA)、X射线衍射仪(XRD)、拉曼光谱(Raman)分析了纳米颗粒的结构和相变温度.使用振动样品磁场计(VSM)测试了样品的磁性能.研究发现:经500℃氩...