TheB 2Σ-X 2Σ system of the CaF molecule

The spectrum of theB ²Σ-X ²Σ system of the CaF molecule has been photographed in the second order of a 10.6 m concave grating spectrograph with 0.33 Å/mm dispersion. The rotational structure of the (0, 0) and (1, 0) bands has been analysed and the precise molecular constants have been obtained. Using the constants so determined the band origins of a large number of bands with 0 <v′,v″ < 10 have been calculated and used to obtain the accurate vibrational constants forB andX states and these are presented.     

Interrelation between inhomogeneity and cyclability in O3‐NaFe1/2Co1/2O2

O3‐NaFe_1/2Co_1/2O₂ shows initial capacity of 160 mAh/g and an average operating voltage of 3.1 V (vs. Na) with good cyclability, and is a promising candidate of the cathode materials for sodium‐ion secondary batteries (SIBs). Here, we found that the cyclability of the slowly‐cooled sample is much worse than that of quenched one, even though the former sample keeps the O3‐type structure. The energy dispersive X‐ray spectroscopy (EDX) images suggest that the slow‐cooled sample (Na_x Fe_1–yCo_y O₂) is inhomogeneous in the Fe concentration (1 – y), perhaps triggered by the Na deficiency (1 – x). We ascribed the poor cyclability in the slowly‐cooled sample to the concentration inhomogeneity (Δy). The Δy is further responsible for the fluctuation of the lattice constants (a and c), as revealed by the Williamson–Hall plot. (© 2016 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)     

Theoretical study on non-sequential double ionization of carbon disulfide with different bond lengths in linearly polarizedlaser fields

By using a two-dimensional Monte-Carlo classical ensemble method, we investigate the double ionization(DI) process of the CS_2 molecule with different bond lengths in an 800-nm intense laser field. The double ionization probability presents a "knee" structure with equilibrium internuclear distance R = 2.9245 a.u.(a.u. is short for atomic unit). As the bond length of CS increases, the DI probability is enhanced and the "knee" structure becomes less obvious. In addition,the momentum distribution of double ionized electrons is also investigated, which shows the momentum mostly distributed in the first and third quadrants with equilibrium internuclear distance R = 2.9245 a.u. As the bond length of CS increases,the electron momentum becomes evenly distributed in the four quadrants. Furthermore, the energy distributions and the corresponding trajectories of the double-ionized electrons versus time are also demonstrated, which show that the bond length of CS in the CS_2 molecule plays a key role in the DI process.     

超衍射成像中 双螺旋点扩展函数的三维定位精度

开关效应和单分子定位的结合可以实现样品的超衍射分辨成像, 双螺旋点扩展函数将单分子定位纳米分辨从二维扩展到了三维.本文对双螺旋点扩展函数的三维定位精度展开了探讨.首先, 基于费希尔信息量, 计算了双螺旋点扩展函数的无偏估计, 得出其理论定位精度, 并分析了光子数、背景噪声以及有效像元尺寸大小对其定位精度的影响; 其次, 基于单分子定位实验过程中对于数据分析通常采用的高斯拟合质心定位算法, 通过误差传递函数定律求得双螺旋点扩展函数的轴向定位精度.计算机模拟结果表明, 在光子数大于1000的条件下, 高斯拟合质心定位精度和费希尔信息量理论定位精度符合较好. 本文的讨论不仅为双螺旋点扩展函数的三维定位精度提供了理论依据, 同时也可为实验提供理论指导. 关键词： 双螺旋点扩展函数 费希尔信息量 定位精度 高斯拟合     

旋转双棱镜光束指向控制技术综述

旋转双棱镜系统通过两棱镜的共轴独立旋转改变光的传播方向,可用于调整光束或视轴指向。与传统的两轴、三轴式光电平台相比,基于旋转双棱镜设计的光束或视轴调整装置具有精度高、结构紧凑、动态性能好等优点,已成为传统光电平台的有益补充。本文分析了双棱镜系统的光束指向调整机制;介绍了国内外相关基础研究的热点问题,主要涉及光束转向机制、光束扫描模式、棱镜回转控制以及棱镜引起的光束变形、成像色差、成像畸变的研究。文中描述了该项技术的应用进展,给出了利用该项技术开发的典型产品以及该项技术在激光光束指向调整和目标搜索、识别与跟踪成像方面的应用。最后,探讨了旋转棱镜在扫描模式、光束质量、成像色差与畸变、回转控制等方面面临的技术难题,并对其发展趋势进行了展望。     

Tunneling magnetoresistance of the double spin-filter junctions at nonzero bias

A recent theoretical estimation indicated that the NM/FI/FI/NM double spin-filter junction (DSFJ, here the NM and FI represent the nonmagnetic electrode and the ferromagnetic insulator (semiconductor) spacer, respectively) could have very high tunneling magnetoresistance (TMR) at zero bias. To meet the requirement in research and application of the magnetoresistance devices, we have calculated the dependences of tunneling magnetoresistance of DSFJ on the bias (voltage), the thicknesses of ferromagnetic insulators (semiconductors) and the average barrier height. Our results show that except its very high value, the TMR of DSFJ does not decrease monotonously and rapidly with rising bias, but increase slowly at first and decrease then after having reached a maximum value. This feature is in distinct contrast to the ordinary magnetic tunnel junction FM/NI/FM (FM and NI denote the ferromagnetic electrode and the nonmagnetic insulator (semiconductor) spacer, respectively), and is of benefit to the use of DSFJ as a magnetoresistance device.     

包层泵浦的L波段Er3+/Yb3+共掺光纤激光器

报道了一种工作波长在L波段的包层泵浦Er³⁺/Yb³⁺共掺光纤环形激光器. 环形腔内的激光工作介质为一段9 m长的Er³⁺/Yb³⁺共掺高掺杂光纤. 利用6个976 nm LD同时抽运前段Er³⁺/Yb³⁺共掺双包层光纤产生的放大自发辐射谱作二次抽运源, 使腔内增义谱由C波段移到L波段, 实现了L波段光纤激光器的稳定输出; 采用包层泵浦技术, 在抽运功率为3594.5 mW时, 测得泵浦入纤功率为2731.8 mW, 实现了输出连续功率最大518.4 mW,斜率效率达到19% 的激光输出; 所形成激光的工作波长为1613.94 nm, 激光光谱的3 dB带宽为1.5 nm, 边模抑制比接近于50 dB.     

双变形镜自适应光学系统像差解耦研究

对由大行程变形镜和高空间频率变形镜组成的双变形镜自适应光学系统中的像差解耦原理和限定像差校正算法做了理论分析。认为在高空间频率变形镜的斜率响应矩阵中加入限定像差向量,根据直接斜率法分别计算出两个变形镜的控制电压,可以实现两个变形镜分别对低阶像差和高阶像差的闭环校正。仿真研究了19单元变形镜和61单元变形镜组成的双变形镜自适应光学系统对低阶像差和高阶像差分别校正的情况,结果说明双变形镜自适应光学系统的校正效果与理想行程的单变形镜自适应光学系统的校正效果相当,避免了制作同时具有大行程和高空间频率两个特征的变形镜。     

TM掺杂Ⅱ-Ⅳ-Ⅴ2黄铜矿半导体的电磁性质

利用自旋局域密度泛函的第一性原理对3d过渡金属(TM=V，Cr，Mn，Fe，Co和Ni)掺杂的Ⅱ-Ⅳ-Ⅴ2(CdGeP2和ZnGeP2)黄铜矿半导体的电磁性质进行系统计算，结果发现：V和Cr掺杂的CdGeP2和ZnGeP2将出现铁磁状态(FM)，Mn，Fe以及Co掺杂的CdGeB和ZnGeP2将出现反铁磁状态(AFM)，而Ni掺杂时，稀磁半导体(DMS)的磁性比较不稳定，其中Cr掺杂的CdGeP2和ZnGeP2将可能是具有较高居里温度Tc的DMS，当TM-3d电子的t2g态部分被填充时，其掺杂的DMS将出现FM状态；而当TM-3d电子的t2g态全满或者全空时，其掺杂的DMS将出现AFM状态，在(Cd，Mn)GeP，和(Zn，Mn)(GeP2中分别掺入电子和空穴载流子，可以发现载流子是否具有TM-3d电子的巡游特性是。DMS是否出现FM状态的主要原因。     

Laser ranging based on electro-optic switch

Based on electro-optic switch effect in crystal, a novel laser ranging method is proposed. CW-laser emitted by laser transmitter propagates forward to the measured target, after being reflected by the target, and then goes back to the transmitter. Close to the transmitter, a special mono-block LiNbO₃ crystal is added into the round-trip light beams. High-voltage pulses with the sharp enough changes in rising edges are loaded on the crystal. Based on electro-optic effect, double refraction and internal double reflection effect in crystal, the crystal cuts off the round-trip light beams, and reflects a light pulse cut out by the crystal to a detector aside from the original beam path. The pulse width T is the period that laser propagates forward and back between the crystal and the target. The feasibility of the new idea is proved by our experiments and a brand-new way for the laser ranging is provided.