Band-stop optical nanofilters with split-ring resonators based on metal–insulator–metal structure

Novel band-stop filters with circular split-ring resonators based on the metal–insulator–metal(MIM) structure are presented, with their transmission properties of SPPs propagating through the filter simulated by the finite-difference timedomain(FDTD) method. The variation of the gap of the split ring can affect the transmission characteristics, i.e., the transmission spectrum of SPPs exhibiting a shift, which is useful for modulating the filter. Linear and nonlinear media are used in the resonator respectively. By varying the refractive index of the linear medium, the transmission properties can be changed obviously, and the effect caused by changing the incident intensity with a nonlinear medium is similar.Several resonant modes that are applicable can be enhanced by changing the position of the gap of the split ring. Thus, the transmission properties can be modulated by adjusting the size of the gap, varying the refractive index, and changing the incident intensity of the input light. These methods may play significant roles in applications of optical integrated circuits and nanostructural devices.     

Preparation of multi-walled carbon nanotube–Fe composites and their application as light weight and broadband electromagnetic wave absorbers

Multi-walled carbon nanotube （MWCNT）-Fe composites were prepared via the metal organic chemical vapor deposi- tion by depositing iron pentacarbonyl on the surface of MWCNTs. The structural and morphological analyses demonstrated that Fe nanoparticles were deposited on the surface of the MWCNTs. The electromagnetic properties of the MWCNTs were significantly changed, and the absorbing capacity evidently improved after the Fe deposition on the MWCNT surface. A minimum reflection loss of -29.4 dB was observed at 8.39 GHz, and the less than -10 dB bandwidth was about 10.6 GHz, which covered the whole X band （8.2-12.4 GHz） and the whole Ku band （12.4-18 GHz）, indicating that the MWCNT-Fe composites could be used as an effective microwave absorption material.     

Structure, room-temperature magnetic and optical properties of Mn-doped TiO2 nano powders prepared by the sol-gel process

TiO 2 nano powders with Mn concentration of 0 at%-12 at% were synthesized by the sol-gel process,and were annealed at 500 C and 800 C in air for 2 hrs.X-ray diffraction (XRD) measurements indicate that the Mn-TiO 2 nano powders with Mn concentration of 1 at% and 2 at% annealed at 500 and 800 C are of pure anatase and rutile,respectively.The scanning electron microscope (SEM) observations reveal that the crystal grain size increases with the annealing temperature,and the high resolution transmission electron microscopy (HRTEM) investigations further indicate that the samples are well crystallized,confirming that Mn has doped into the TiO 2 crystal lattice effectively.The room temperature ferromagnetism,which could be explained within the scope of the bound magnetic polaron (BMP) theory,is detected in the Mn-TiO 2 samples with Mn concentration of 2 at%,and the magnetization of the powders annealed at 500 C is stronger than that of the sample treated at 800 C.The UV-VIS diffuse reflectance spectra results demonstrate that the absorption of the TiO 2 powders could be enlarged by the enhanced trapped electron absorption caused by Mn doping.     

Light manipulation in organic light‐emitting devices by integrating micro/nano patterns

The demonstration of high efficiency and color tunability has brought organic light‐emitting devices (OLEDs) into the lighting and display market. High efficiency is one of the key issues for their commercial applications, for which much effort has been devoted to developing novel materials and device structures. It is well known that around 80% of the generated photons are trapped in OLED structure, so that there is still the greatest scope for significant improvements in its efficiency. This has driven the research towards the integration of micro/nano patterns into device structures that benefit from their abilities in manipulating the generation and propagation of photons. Micro/nano patterns with random or periodic morphologies have demonstrated their effect on the outcoupling of the trapped photons within the device. Moreover, the emitting properties other than the light extraction could be manipulated by introducing the micro/nano patterns. This article reviews the recent progresses in improving the light extraction and manipulating the emission properties of the OLEDs through the introduction of the micro/nano patterns by various fabrication strategies. The light manipulation of the micro/nano patterns in organic photovoltaics is briefly discussed considering its similar working principle and fabrication strategies to that of the OLEDs.

     

Experimental and theoretical evaluation of wettability on micro/nano hierarchically engineered surfaces based on robust micro-post-arrayed- and highly ordered nano-rippled-structures

This paper reports a simple approach for demonstrating a micro/nano hierarchical surface, ensuring both geometrical regularity and mechanical stability, for improving the hydrophobicity. The proposed dual-scale hierarchical surfaces were realized simply by combining the highly self-ordered ripple-like nano patterns with the robust micro-post arrays, based on the cost-effective nonlithographic chemical oxidation process and well-established microfabrication technologies. The wettability of the proposed nano-scale mono- and micro/nano dual-roughened surfaces was evaluated by measuring the apparent contact angles (ACAs), and analyzed theoretically with analytic models based on the Wenzel, Cassie, and combined wetting theories. Through experimental and theoretical observations, it was found that the proposed micro/nano hierarchical structures can improve the wetting property and the superhydrophobic robustness of high- and low-density micro-post arrayed surfaces, respectively.     

微纳尺度热能调控的声子学元器件研究进展

声子是半导体材料中热能的主要载体。通过对声子调控的深入研究,人们可以为微纳电子器件散热和热能转换提供有效的解决方案。文章介绍了热能调控声子学元器件的研究进展,重点阐述了理论上如何利用微纳米结构材料构建声子学基本单元——热二极管/热整流器。此外,文章还介绍了该领域的关键测量技术和实验进展,包括热整流器和热存储器的设计与实现。最后对声子学研究的发展趋势进行了展望,并提出了存在的困难和挑战。     

质子与金属布线层核反应对微纳级静态随机存储器单粒子效应的影响分析

金属布线层对微纳级静态随机存储器(static random access memory, SRAM) 质子单粒子效应敏感性的影响值得关注. 利用Geant4针对不同能量(30 MeV, 100 MeV, 200 MeV和500 MeV)的质子与微纳级SRAM器件的核反应过程开展计算, 研究了核反应次级粒子的种类、线性能量传输值(linear energy transfer, LET)及射程情况, 尤其对高LET 值的核反应次级粒子及其射程开展了详细分析. 研究表明, 金属布线层的存在和质子能量的增大为原子序数大于或等于30的重核次级粒子的产生创造了条件, 器件体硅区中原子序数大于60的重核离子来源于质子与钨材料的核反应, 核反应过程中的特殊作用机理会生成原子序数在30至50之间的次级粒子, 且质子能量的增大有助于这种作用机理的发生, 原子序数在30至50之间的次级粒子在器件体硅区的LET值最大约为37 MeV·cm²/mg, 相应射程可达到几微米, 对于阱深在微米量级的微纳级SRAM器件而言, 有引发单粒子闩锁的可能. 研究结果为空间辐射环境中宇航器件的质子单粒子效应研究提供理论支撑.     

工艺误差对电容式微加速度计温度漂移的影响（英）

利用有限元方法,仿真分析了深反应离子刻蚀工艺造成的折叠梁宽度误差对电容式微加速度计温度漂移的影响。在存在工艺误差和保证微加速度计灵敏度恒定的前提下,增大了折叠梁设计宽度,计算了不同宽度下微加速度计的温度漂移量。结果表明:刻蚀工艺误差越大,微加速度计温度漂移量越大。折叠梁设计宽度为4.5 m和6.5 m时,最大温度漂移量分别为2.42 mg/℃和1.71 mg/℃,因此通过适当地增大设计尺寸,可以有效地减小微加速度计的温度漂移量。     

Emission of weak electrons: Dosimetry of nanovolumes

Modern radiation therapy (RT) technologies and the needs of molecular and micro radiobiology have necessitated the detection of radiation absorbed by micro/nano volumes. The possibility of developing a nano/micro-scale dosimeter is demonstrated via the use of prethreshold photoelectron and exoelectron emission from solid-state nanolayers (Si, bone) and nanofilms (ZrO2:PbS). The experiments indicate that the absorbed dose threshold depends on the detector origin.     

The performances of silicon solar cell with core–shell p-n junctions of micro-nano pillars fabricated by cesium chloride self-assembly and dry etching

Silicon micro-nano pillars are cost-efficiently integrated using twice cesium chloride (CsCl) islands lithography technique and dry etching for solar cell applications. The micro PMMA islands are fabricated by inductively coupled plasma (ICP) dry etching with micro CsCl islands as masks, and the nano CsCl islands with nano sizes then are made on the surface of micro PMMA islands and silicon. By ICP dry etching with the mask of micro PMMA islands and nano CsCl islands, the micro-nano silicon pillars are made and certain height micro pillars are randomly positioned between dense arrays of nano pillars with different morphologies by controlling etching conditions. With 300 nm depth p-n junction detected by secondary-ion mass spectrometry (SIMS), the micro pillars of the diameter about 1 μm form the core–shell p-n junction to maximize utility of p-n junction interface and enable efficient free carrier collection, and the nano tapered pillars of 150 nm diameter are used to decrease reflection by a graded-refractive-index. Compared to single micro or nano pillar arrayed cells, the co-integrated solar cell with micro and nano pillars demonstrates improved photovoltaic characteristic that is a photovoltaic conversion efficiency (PCE) of 15.35 % with a short circuit current density (J _sc) of 38.40 mA/cm² and an open circuit voltage (V _oc) of 555.7 mV, which benefits from the advantages of micro-nano pillar structures and can be further improved upon process optimization.     

基于扭秤的激光干涉差动测量微小冲量方法

基于扭秤测量冲量原理,结合激光干涉法差动测量角度的方法,提出一种基于扭秤的激光干涉差动测量微小冲量的方法。介绍系统的基本组成和测量过程,给出扭秤结构设计参数,并对系统参数进行了标定,结合设计参数与标定结果,对系统的分辨率、量程和精度进行了校核,在典型的测量环境下,对激光烧蚀靶材所形成的Ns量级微小冲量进行了测量,给出了典型的测量结果并进行分析。结果表明:所提出的基于扭秤的激光干涉差动测量微小冲量方法,系统分辨率可达10-7Ns量级,测量范围跨5个数量级,最大可以测量10-2Ns量级冲量,测量精度优于95%。     

X射线照片密度与显微密度计信号电压之间关系的实验探讨

探索了 X射线照片密度与显微密度计信号电压之间的关系。利用曲线拟合得到了 X射线照片光密度与输出电压关系的公式。经公式计算的密度值与实测密度值之间差别不大 ,其标准估计误差为 0 .0 178,完全可以用计算密度值来代替实测密度值。直接取其显微密度计输出的电信号 ,经公式转换成光学密度值后再进行 X射线照片的各种性能测试 ,避免了部分测试和换算误差 ,克服了过去密度测量的不便 ,提高了效率     

Structural complexity of disordered surfaces: Analyzing the porous silicon SFM patterns

This paper introduces a relative structural complexity measure for the characterization of disordered surfaces. Numerical solutions of 2d+1 KPZ equation and scanning force microscopy (SFM) patterns of porous silicon samples are analyzed using this methodology. The results and phenomenological interpretation indicate that the proposed measure is efficient for quantitatively characterize the structural complexity of disordered surfaces (and interfaces) observed and/or simulated in nano, micro and ordinary scales.     

Quantum critical point of an itinerant antiferromagnet in a heavy fermion

A quantum critical point of the heavy fermion Ce(Ru(1-x)Rh(x))2Si2, (x = 0,0.03) has been studied by single-crystalline neutron scattering. By accurately measuring the dynamical susceptibility at the antiferromagnetic wave vector k3 = 0.35c*, we have shown that the inverse energy width gamma(k3), i.e., the inverse correlation time, depends on temperature as gamma(k3) = c1 + c2T((3/2)+/-0.1), where c1 and c2 are x dependent constants, in a low temperature range. This critical exponent 3/2 +/- 0.1 proves that the quantum critical point is controlled by that of the itinerant antiferromagnet.     

Search for V+A current in top-quark decays in pp collisions at sqrts=1.96 TeV

We report an upper limit on the fraction of V+A current, fV+A, in top-quark decays, using approximately 700 pb-1 of pp[over ] collisions at sqrts=1.96 TeV acquired by the upgraded Collider Detector at Fermilab. For the decay t-->Wb-->lnub (where l=e or micro), the invariant mass of the charged lepton and the bottom quark jet is sensitive to the polarization of the W boson. We determine fV+A=-0.06+/-0.25 given a top-quark mass of 175 GeV/c2. We set an upper limit on fV+A of 0.29 at the 95% confidence level, an improvement by a factor of 2 on the previous best direct limit.     

A Nano‐Micro Hybrid Structure Composed of Fe7S8 Nanoparticles Embedded in Nitrogen‐Doped Porous Carbon Framework for High‐Performance Lithium/Sodium‐Ion Batteries

Iron sulfides are attractive anode materials for lithium‐ion batteries (LIBs) and sodium‐ion batteries (SIBs) due to their high theoretical capacities, low cost, and eco‐friendliness. However, their real application is greatly hindered by the rapid capacity fading caused by the large volume changes and sluggish kinetics of iron sulfides during the charge and discharge processes. Combining with carbonaceous materials and tuning the structure at nanoscale are essential to address this issue. Here, a facile hydrothermal method coupled with a carbonization process is developed to synthesize a nano‐micro hybrid porous structure, which is composed of Fe₇S₈ nanoparticles embedded in nitrogen‐doped carbon framework (Fe₇S₈@NC‐PS). This hierarchical sphere is constructed by interconnected 2D nanowalls. The as‐prepared Fe₇S₈@NC‐PS electrodes reveal excellent rate capability and cycling stability in LIBs and SIBs. The remarkable electrochemical properties are attributed to the porous nano‐micro hybrid architecture and the high conductivity and structural stability of the nitrogen‐doped carbon framework.     

光谱共焦测量系统中的色散透镜组设计

光谱共焦位移测量系统具有精度高、质量轻、体积小和灵敏高等优点,可以实现在各种极端情况下的微位移测量。在光谱共焦测量系统中色散透镜组的色散特性决定了整个测量系统的性能。对色散透镜组的测量需求进行了分析,提出了详细的设计指标,基于折射、衍射两种方法对透镜组进行了设计和优化,给出了设计结果。色散透镜组的色散范围为2.2mm,光谱范围为500～700nm,线性度较好。利用分辨率为0.5nm的光谱仪接收光谱信息,理论上精度优于2μm。     

非荧光硫化锌纳米簇的合成与表征

合成硫化锌纳米簇并对其进行表征,建立一种利用硫化锌纳米簇的阳离子交换(CX)反应检测痕量生物分子的方法。采用水热法合成非荧光硫化锌纳米簇(NCCs)并对其进行表征。纳米簇的性能直接影响检测结果。通过透射电镜图像和X射线衍射可知,纳米簇是多孔的,可以通过快速阳离子交换反应从纳米簇中释放大量的Zn2+,在锌响应试剂的作用下产生荧光信号进行荧光检测。其晶体的外部比内部排列松散,有利于快速阳离子交换,其晶体尺寸大小与加热时间有关。通过比表面积检测法测定纳米簇的表面积和孔径表明,最小的纳米簇拥有相对较大的表面积及较高的阳离子交换效率。实验了三种释放方法(酸溶解法、阳离子交换法和微波辅助阳离子交换法)对Zn2+释放性能的影响,结果表明,微波辅助阳离子交换法信噪比较高,操作简便,可用于硫化锌纳米簇免疫测定法中。比较了Zn2+的释放效率和目标结合力与平均直径之间的关系,结果表明纳米簇尺寸为44 nm时表现出最高的阳离子交换效率。结论：所有这些特点,使ZnS纳米簇阳离子交换放大器在痕量生物分子检测方面成为高度灵敏、生物相容性好、低廉环保的检测工具。     

紧凑型X-pinch装置探头标定

介绍了紧凑型X-pinch脉冲功率装置的电流电压测量设计方法。根据该装置的同轴传输线结构特点,研制了一种利用金属膜连接传输线外筒与负载外筒,构成回路测量负载电流的探头。在传输线末端设计电容分压器作为测量负载电压的探头,并利用电路模拟软件对此过程进行模拟,同时这两个探头需要进行在线标定。实验研究结果表明,该探头性能稳定、响应快,是测量负载电流与电压的理想工具。     

紧凑型X-pinch装置探头标定

 介绍了紧凑型X-pinch脉冲功率装置的电流电压测量设计方法。根据该装置的同轴传输线结构特点,研制了一种利用金属膜连接传输线外筒与负载外筒,构成回路测量负载电流的探头。在传输线末端设计电容分压器作为测量负载电压的探头,并利用电路模拟软件对此过程进行模拟,同时这两个探头需要进行在线标定。实验研究结果表明,该探头性能稳定、响应快,是测量负载电流与电压的理想工具。