HIRFL上合成的第一个新核素—208Hg

本文简述在中科院近物所HIRFL上发现的第一个新核素208Hg的合成和鉴别,兼论利用HIRFL提供的中能重离子束开展远离β稳定线核素合成和衰变研究的优势、困难以及拟采用的物理和技术路线。 The synthesis and identification of the first discovered new nuclide 208Hg on HIRFL(Heavy Ion Research Facility of Lanzhou) were described. In this paper the superiorities, difficultiesas well as the physical and technical line about the synthesis and decay study for the nuclides far fromβ-stability line to be made at HIRFL were discussed.     

Spinel lithium titanate (Li4Ti5O12) as novel anode material for room-temperature sodium-ion battery

This is the first time that a novel anode material, spinel Li₄Ti₅O₁₂ which is well known as a “zero-strain” anode material for lithium storage, has been introduced for sodium-ion battery. The Li₄Ti₅O₁₂ shows an average Na storage voltage of about 1.0 V and a reversible capacity of about 145 mAh/g, thereby making it a promising anode for sodium-ion battery. E_x-situ X-ray diffraction (XRD) is used to investigate the structure change in the Na insertion/deinsertion process. Based on this, a possible Na storage mechanism is proposed.     

Exploration of the sum of flexoelectric coef ficients of nematic liquid crystals

We present a theoretical calculation of the dependence of reflectivity Rpp of the improved fully leaky waveguide geometry,which comprises pyramid,matching fluid,and strongly anchored hybrid aligned nematic liquid crystal(NLC) cell on the internal angle.The calculation is based on the multi layer optical theory and the elastic theory of liquid crystals.For different sums of flexoelectric coefficients e11 and e33,the curve of Rpp moves a distance to the left or the right relative to the case of ignoring the flexoelectric effect and the distance of the movement varies with different flexoelectric coefficients.Consequently,the sum of flexoelectric coefficients can be explored by measuring the distance of the movement.     

Enhancement of upconversion luminescence of YAlO3:Er3+ by Gd3+ doping

The upconversion luminescences of YAlO3:Er3+ phosphor co-doping with different Gd3+ concentrations are investigated under the excitation of 980- and 532-nm diode lasers. A near ultraviolet upconversion emission at 410 nm is observed in YAlO3 under 532-nm excitation. Moreover, the inactive Gd3+ ions can improve the upconversion intensity efficiently in a certain range of concentration. Under 980-nm excitation, the visible upconversion emissions at 546 and 646 nm are enhanced by about 10 and 8 times at the Gd3+ concentration of 40%, respectively. The upconversion emission at 410 nm under 532-nm excitation is also enhanced by 7 times. The substitution of Gd3+ ions for Y3+ sites changes the local symmetry of Er3+, leading to the improvement of upconversion efficiency.     

Spectroscopic properties of thulium ions in bismuth silicate glass

A new type of bismuth silicate glass (Bi2O3-SiO2-ZnO-Al2O3-La2O3) doped with Tm2O3 is prepared by melt-quenching method. The thermal stability of the glass is examined by differential scanning calorimetry. No crystallization peak is found. Using the absorption and emission spectra, the absorption and emission cross-sections are calculated. Their maximum data are 2.9×10-21cm2 at 1663 nm and 4.7×10-21cm2 at 1826 nm, respectively. Using the Judd-Ofelt theory, the radiation transition probabilities and radiative lifetimes are obtained. The extended overlap integral method is applied to analyze energy transfer process among the Tm3+ ions. The transfer constants of cross-relaxation and energy migration among the Tm3+ ions at the 3H4 level are 7.60×10-40 and 14.98×10-40 cm6 /s, respectively. The critical transfer radius for cross-relaxation is 0.99 nm. The cross relaxation process is easy to realize and is favorable for obtaining ～2-μm laser.     

Experimental study on the 1.94-μm laser performance of c-Cut Tm:YAP crystal with various doping concentration

The influence of the thulium ion concentration on the 1.94-??m laser performance of c-cut Tm:YAP crystal was investigated in this paper. Three crystals with 3, 4, and 5% Tm³⁺ (atom concentration) were examined at 18°C. Our experimental results showed that, the best power performance was obtained with the 4% Tm:YAP crystal. By using 24.8 W of incident pump power at 795 nm, a maximum of 7.5 W of output power was obtained. The slope efficiency was 48.8%, corresponding to diode-to-Tm conversion efficiency of 30.2%.     

晶体硅太阳电池双层电极优化分析与实验研究

相对于单层电极结构,优化的前表面双层电极能够明显减小功率损失,改善晶体硅太阳电池的电学特性．本文对晶体硅太阳电池的双层电极进行了优化分析和实验研究.通过扫描电子显微镜观测将双层电极的截面抽象为更接近于实际的半椭圆型,建立了太阳电池前表面的双层电极模型,理论分析了双层电极的电学损失和光学损失.结合丝网印刷后光诱导电镀太阳电池的实验,得到了理论和实验上的最优化光诱导电镀增厚电极厚度与丝网印刷电极宽度的关系.所得到的理论和实验结果符合良好.由于并不涉及电极制备的具体技术,双层电极理论模型普遍适用于多种类型的双层电极结构.     

数字域时间延迟积分时间CMOS相机高分“凝视”成像设计分析

为实现凝视卫星高分跟踪成像,设计了数字域时间延迟积分(TDI)互补金属氧化物半导体(CMOS)传感器在凝视姿态下的成像匹配模型,推导了卫星凝视跟踪成像时相对轨道坐标系的姿态变化,采用坐标变换方法实时计算其在凝视过程中随姿态变化的行转移时间,利用蒙特卡罗方法统计计算了凝视模式下姿态指向精度和稳定度对成像的影响。利用数字域TDI CMOS原理样机和小卫星姿态控制系统全物理仿真平台对成像进行了仿真分析。结果表明,卫星的姿态控制精度在成像过程中会引起纵向的像移速度失配和横向匹配的残余像移,成像积分级数越高,图像信噪比越大。积分级数的增加对卫星姿态提出较高要求,仿真平台姿态角和姿态角速度控制精度分别优于0.05°,0.005°/s时,采用积分级数为48级能较好地满足成像质量要求。     

基于动态溶胀法制备中空聚合物微球

以表面带正电荷的m级聚苯乙烯微球为种子,经过甲苯、二乙烯基苯溶胀,聚合与包覆等过程制备了直径约5 m的中空聚合物微球。研究了溶剂类型、溶剂用量对动态溶胀法制备的中空聚合物微球粒径、分布和结构的影响,讨论了中空聚合物微球的形成机理。结果表明:添加一定量甲苯、二甲苯等挥发性溶剂是动态溶胀法形成中空聚合物微球的前提;甲苯用量越多,溶胀后形成的中空结构越明显,孔径越大;选择低溶解性的二甲苯溶剂更有利于中空结构的形成。     

Dark pulse generation in a dispersion-managed fiber laser

We report an experimental observation of dark pulse generation in a dispersion-managed erbium-doped fiber laser with net anomalous cavity group-velocity dispersion. It is found that apart from the bright soliton pulses, dark pulses with spectral sidebands could be obtained in the laser under appropriate operating conditions. The generation of dark pulses may be attributed to soliton shaping in the cavity.