Sustainable Route for Synthesizing Aluminosilicate EU-1 Zeolite

Developing sustainable routes for the synthesis of zeolites is still a vital and challenging task in zeolite scientific community. One of the typical examples is sustainable synthesis of aluminosilicate EU-1 zeolite, which is not very efficient and environmental-unfriendly under hydrothermal condition due to the use of a large amount of water as solvent. Herein, we report a sustainable synthesis route for aluminosilicate EU-1 zeolite without the use of solvent for the first time. The physicochemical properties of the obtained EU-1 zeolite are characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetry-differential thermal analysis (TG-DTA), N₂ sorption, inductively coupled plasma (ICP) analysis, and solid nuclear magnetic resonance (NMR), which show the product has high crystallinity, uniform morphology, large BET surface area, and four-coordinated aluminum species. Moreover, the impact of synthesis conditions is investigated in detail. The sustainable synthesis of aluminosilicate EU-1 zeolite under solvent-free     

Cationic Nonporous Macrocyclic Organic Compounds for Multimedia Iodine Capture

Over the past two decades, progress in chemistry has generated various types of porous materials for removing iodine (¹²⁹I or ¹³¹I) that can be formed during nuclear energy generation or nuclear waste storage. However, most studies for iodine capture are based on the weak host-guest interactions of the porous materials. Here, we present two cationic nonporous macrocyclic organic compounds, namely, MOC-1 and MOC-2 , in which 6I^- and 8I⁻ were as counter anions, for highly efficient iodine capture. MOC-1 and MOC-2 were formed by reacting 1,1′-diamino-4,4′-bipyridylium di-iodide with 1,2-diformylbenzene or 1,3-diformylbenzene, respectively. The presence of a large number of I⁻ anions results in high I₂ affinity with uptake capacities up to 2.15 g ⋅ g⁻¹ for MOC-1 and 2.25 g ⋅ g⁻¹ for MOC-2 .     

Analysis of Asymmetric Long-Range Surface-Plasmon Waveguide with High-Confinement Mode

We model and study the asymmetric long-range surface-plasmon waveguides using the finite-element method. We introduce two types of asymmetric structures and discuss their modal properties compared to traditional long-range surface-plasmon waveguides. Although the propagation distance is decreased, the energy-confinement capability is improved for asymmetric long-range waveguiding structures when the geometrical parameters are properly selected. Our simulation result offers guidance for tuning properties of plasmonic waveguides and providing ways for enhancing electromagnetic energy confinement in long-range surface-plasmon waveguides.     

氟利昂F113分子在飞秒激光作用下的多光子电离解离动力学

大气臭氧层因吸收太阳紫外光, 是人类必不可少的保护伞. 氟利昂在太阳光辐射下解离生成破坏臭氧的游离态氯原子, 是破坏大气臭氧层的主要元凶之一. 本文利用飞行时间质谱技术和离子速度成像技术研究了氟利昂F113(三氟三氯乙烷)分子在800 nm 飞秒光作用下的多光子电离解离动力学. 利用飞行时间质谱探测技术, 得到了三氟三氯乙烷在该波长飞秒激光作用下发生多光子电离解离产生的碎片质谱. 通过荷质比对碎片质谱进行了详细的标定和分析. 在质谱上未发现母体离子, 所有观察到的离子都是由于激光脉冲作用下产生的碎片. 三个最主要的碎片离子是CFCl₂⁺, CF₂Cl⁺, C₂F₃Cl₂⁺. 通过飞行时间质谱标定, 发现并归属了多个解离通道. 三个主要的解离机理分别为: 1) C-Cl键断裂直接生产氯自由基的通道C₂F₃Cl₃⁺→C₂F₃Cl₂⁺+Cl; 2) C--C键断裂C₂F₃Cl₃⁺→CFCl₂⁺+CF₂Cl; 3) C--C键断裂C₂F₃Cl₃⁺→CF₂Cl⁺+CFCl₂. 利用离子速度成像技术对这三个主要通道产生的碎片离子进行成像, 得到了C₂F₃Cl₂⁺, CFCl₂⁺和CF₂Cl⁺离子的速度影像. 由C--Cl键断裂产生的碎片离子C₂F₃Cl₂^{+}的速度分布由两个高斯分布曲线拟合, 而由C--C键断裂产生的碎片离子CFCl₂⁺和CF₂Cl⁺可以用一个高斯曲线拟合. 通过影像分析得到了解离碎片的平动能分布和角向分布各向异性参数等详尽的动力学信息. 结合高精度密度泛函理论计算对解离动力学进行了进一步的分析和讨论.深入认识氟利昂的解离动力学可为进一步控制破坏臭氧层提供理论参考和实验依据.     

V掺杂ZnO透明导电薄膜研究

本文分别采用磁控溅射技术与基于密度泛函理论的平面波赝势方法两种方式, 对高价态差元素V掺杂ZnO薄膜进行研究. 实验研究结果表明: V的掺入并未改变ZnO的生长方式, 所制备的薄膜都呈(002)择优生长; 随着衬底温度增加, VZO薄膜的结晶质量逐步改善, 当衬底温度超过280 ℃时薄膜的结晶质量恶化; 在280 ℃时获得的VZO薄膜电阻率最低3.8×10^-3 Ω·m, 500-2000 nm平均透过率高于85%. 理论模拟结果表明: V以替位形式掺入ZnO六角纤锌矿晶格结构中, 费米能级进入导带, 材料表现出n 型半导体的特性, 导电电子主要由V 3d及O 2p电子轨道提供. 理论计算结果与实验结果的一致性, 表明VZO薄膜具有作为高效Si基薄膜太阳电池透明导电薄膜的应用潜力.     

Quantum state and process tomography via adaptive measurements

We investigate quantum state tomography(QST) for pure states and quantum process tomography(QPT) for unitary channels via adaptive measurements. For a quantum system with a d-dimensional Hilbert space, we first propose an adaptive protocol where only 2d. 1 measurement outcomes are used to accomplish the QST for all pure states. This idea is then extended to study QPT for unitary channels, where an adaptive unitary process tomography(AUPT) protocol of d2+d.1measurement outcomes is constructed for any unitary channel. We experimentally implement the AUPT protocol in a 2-qubit nuclear magnetic resonance system. We examine the performance of the AUPT protocol when applied to Hadamard gate, T gate(/8 phase gate), and controlled-NOT gate,respectively, as these gates form the universal gate set for quantum information processing purpose. As a comparison, standard QPT is also implemented for each gate. Our experimental results show that the AUPT protocol that reconstructing unitary channels via adaptive measurements significantly reduce the number of experiments required by standard QPT without considerable loss of fidelity.     

Observation of large low‐field magnetoresistance in spinel cobaltite: A new half‐metal

Low‐field magnetoresistance is an effective and energy‐saving way to use half‐metallic materials in magnetic reading heads and magnetic random access memory. Common spin‐polarized materials with low field magnetoresistance effect are perovskite‐type manganese, cobalt, and molybdenum oxides. In this study, we report a new type of spinel cobaltite materials, self‐assembled nanocrystalline NiCo₂O₄, which shows large low field magnetoresistance as large as –19.1% at 0.5 T and –50% at 9 T (2 K). The large low field magnetoresistance is attributed to the fast magnetization rotation of the core nanocrystals. The surface spin‐glass is responsible for the observed weak saturation of magnetoresistance under high fields. Our calculation demonstrates that the half‐metallicity of NiCo₂O₄ comes from the hopping e_g electrons within the tetrahedral Co‐atoms and the octahedral Ni‐atoms. The discovery of large low‐field magnetoresistance in simple spinel oxide NiCo₂O₄, a non‐perovskite oxide, leads to an extended family of low‐field magnetoresistance materials. (© 2016 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)     

Hybrid process for texturization of diamond wire sawn multicrystalline silicon solar cell

Acid texture is difficult for diamond wire sawn (DWS) multicrystalline silicon (mc‐Si) wafer owing to the inhomogeneous distribution of damage layer on the surface. In this article, metal‐assisted chemical etching (MACE) has been selected for introducing a porous seeding layer to induce acid texturing etching. SEM results show that the oval pit structures coverage get obvious improvement even on the smooth areas. Owing to the further improved light absorption ability by second MACE and nanostructure rebuilding (NSR) process, nanostructured DWS mc‐Si solar cell has exhibited a conversion efficiency of 17.96%, which is 0.45% higher than that of DWS wafer with simple acid texture process. (© 2016 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)     

P‐type tin‐oxide thin film transistors for blue‐light detection application

We reported the characteristics of p‐type tin‐oxide (SnO) thin film transistors (TFTs) upon illumination with visible light. Our p‐type TFT device using the SnO film as the active channel layer exhibits high sensitivity toward the blue‐light with a high light/dark read current ratio (I_light/I_dark) of 8.2 × 10³ at a very low driven voltage of <3 V. Since sensing of blue‐light radiation is very critical to our eyes, the proposed p‐type SnO TFTs with high sensitivity toward the blue‐light show great potential for future blue‐light detection applications.

     

Preliminary investigation into feasibility of dissolved methane measurement using cavity ringdown spectroscopy technique

For the exploration of gas hydrate resources by measuring the dissolved methane concentration in seawater, a continuous-wave cavity ringdown spectroscopy (CW-CRDS) experimental setup was constructed for trace methane detection. A current-modulation method, rather than a cavity-modulation method using an optical switch and a piezoelectric transducer, was employed to realize the cavity excitation and shutoff. Such a current-modulation method enabled the improvement of the experimental setup construction and stability, and the system size and stability are critical for a sensor to be deployed underwater. Ringdown data acquisition and processing were performed, followed by an evaluation of the experimental setup stability and sensitivity. The obtained results demonstrate that great errors are introduced when a large fitting window is selected if the analog-to-digital converter has an insufficient resolution. The ringdown spectrum of methane corresponding to the 2v ₃ band R(4) branch was captured, and the methane concentration in lab air was determined to be 2.06 ppm. Further experiments for evaluating the quantitative ability of this CW-CRDS experimental setup are underway from which a high-sensitivity methane sensor that can be combined with a degassing system is expected.