The synthesis of aligned silicon nanowires under ambient atmospheric pressure

Highly ordered amorphous silicon nanowires were successfully synthesized from single crystalline silicon wafer at the pyrolysis temperature of 1050 °C under ambient atmospheric pressure. Both poly (phenylcarbyne) and nickel nitrate played important roles in the growth of silicon nanowires. The fabrication of ordered silicon nanowires was controllable and repeatable, confirmed by the experimental results. The morphology and microstructure analysis of the as-obtained samples showed the highly ordered amorphous silicon nanowires were obtained, determined by scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and FT-infrared spectroscopy. A solid-liquid-solid growing process was proposed.     

Extractive Atmospheric Pressure Photoionization (EAPPI) Mass Spectrometry: Rapid Analysis of Chemicals in Complex Matrices

Extractive atmospheric pressure photoionization (EAPPI) mass spectrometry was designed for rapid qualitative and quantitative analysis of chemicals in complex matrices. In this method, an ultrasonic nebulization system was applied to sample extraction, nebulization, and vaporization. Mixed with a gaseous dopant, vaporized analytes were ionized through ambient photon-induced ion–molecule reactions, and were mass-analyzed by a high resolution time-of-flight mass spectrometer (TOF-MS). After careful optimization and testing with pure sample solution, EAPPI was successfully applied to the fast screening of capsules, soil, natural products, and viscous compounds. Analysis was completed within a few seconds without the need for preseparation. Moreover, the quantification capability of EAPPI for matrices was evaluated by analyzing six polycyclic aromatic hydrocarbons (PAHs) in soil. The correlation coefficients (R ² ) for standard curves of all six PAHs were above 0.99, and the detection limits were in the range of 0.16–0.34 ng/mg. In addition, EAPPI could also be used to monitor organic chemical reactions in real time.

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Enhanced thermal degradation of 2,2′-dichlorodiethyl sulfide (sulfur mustard,HD) with the presence of metal oxides

Thermal degradation of sulfur mustard (2,2′-dichlorodiethyl sulfide, HD) in the presence of metal oxide adsorbents was investigated by thermal desorption in conjunction with gas chromatography–mass spectrometry (GC-MS). Zr(OH)₄, Al₂O₃, Al₂CoO₄, MgO, CeO₂, and V₂O₅ were used as metal oxide adsorbents. Neat HD was spiked onto the metal oxides packed in glass tubes, which were kept at room temperature and then heated at moderately elevated temperatures of 100°C by a thermal desorption system. The products of thermal degradation were directly transferred and analyzed by GC-MS. 1,4-Dithiane and 1,4-oxathiane were characterized as the major products of the thermal degradation of HD in the presence of Zr(OH)₄, Al₂O₃, Al₂CoO₄, and CeO₂ adsorbents. No effective degradation was observed with MgO and V₂O₅. Of particular note is Zr(OH)₄, which extremely enhanced the thermal degradation of HD.     

Plasmon-induced absorption in stacked metamaterials based on phase retardation

In this paper, based on the constructive interference of plasmonic dipolar and quadrupolar modes, a classical analogue of electromagnetically induced absorption （EIA） is demonstrated theoretically in a stacked metamaterial consisting of a short metal strip （which acts as a bright resonator） and a long metal strip （acting as a dark resonator）, which has been reported to support the electromagnetically induced transparency （EIT） effect. The transition from EIA to EIT can be clearly observed in the absorbance spectra via varying the vertical spacing between two resonant oscillators. With the help of the coupled two-oscillator model, the phase shift between the bright and dark resonance modes is calculated by fitting the simulated absorbance spectra, which reveals the physical mechanisms behind constructive and destructive interference effects in EIT/EIA metamaterials.     

Designing of a polarization beam splitter for the wavelength of 1310 nm on dual-core photonic crystal fiber with high birefringence and double-zero dispersion

We have proposed a novel kind of photonic crystal fiber which contains two asymmetric cores. The bireti＇ingence and the dispersion are numerically analyzed based on finite element method when the size of the air holes and the pitch of two adjacent air holes are changed. It is shown that the proposed photonic crystal fiber has high birefringence up to the order of 10-2 and double-zero dispersion points are at the wavelengths of 1310 nm and 800 rim, simultaneously. At the same time, the normalized power and the extinction ratios of the proposed photonic crystal fiber have been simulated. It is demonstrated that, at the wavelength of 1310 rim, the x-polarized mode and the y-polarized mode are separated when the propagation distance is 2.481 ram.     

Investigation on landing impact dynamic and low-gravity experiments for deep space lander

Herein symmetrical four-legged suspension lunar lander was used as the research object, the six-degree-of-freedom dynamic model was built and the model of the lunar soil friction coefficient was improved. For the low-gravity simulation on objects outside earth for future work, the law of dynamic similarity for detectors was deduced. A new method was proposed for simulating the low-gravity field on the surface of objects outside earth, which was achieved by changing initial conditions of the landing by the probe and by subsequent treatment of experimental data. The prototype tested the limitation of this method was verified. It is shown that the prototypes of detectors can be used in detectors low-gravity simulation test with this method, and equipments are simple and operationally effective. This method can be used for later lunar exploration, and low-gravity simulations on extraterrestrial objects.     

Three‐dimensional visible‐light capsule enclosing perfect supersized darkness via antiresolution

Supersized darkness in three dimensions surrounded by all light in free space is demonstrated theoretically and experimentally in the visible regime. The object staying in the darkness is similar to staying in an empty light capsule because light just bypasses it by resorting to destructive interference. A binary‐optical system is designed and fabricated based on achieving antiresolution (AR), by which electromagnetic energy flux avoids and bends smoothly around a nearly perfect darkness region. AR remains an unexplored topic hitherto, in contrast to the super‐resolution for realizing high spatial resolution. This novel scheme replies on smearing out the point spread function and thus poses less stringent limitations upon the object's size and position since the created dark (zero‐field) area reach 8 orders of magnitude larger than λ² in cross‐sectional size. It functions very well with arbitrarily polarized beams in three dimensions, which is also frequency scalable in the whole electromagnetic spectrum.     

Generation and circuit implementation of multi-block multidirectional grid multi-scroll chaotic attractors

Due to the dynamic characteristics of the Chua's system, multi-scroll chaotic attractors are still confined in a single block and fail to break the limit. This paper proposes an approach for generating novel multi-block multidirectional grid multi-scroll chaotic attractors that can break the limit via novel nonlinear modulating functions. According to this method, the recursion rules used to generate multi-block multidirectional grid multi-scroll attractors are mathematically obtained. The new system is autonomous; the effectiveness of this method has been verified by theoretical analysis, numerical simulation, and circuit implementation.     

染料敏化太阳能电池二氧化锡光阳极表面原子层沉积氧化铝研究

染料敏化薄膜太阳能电池作为一种新型的太阳能电池吸引了世界范围内的研究。采用二氧化锡代替传统的二氧化钛作为染料敏化太阳能电池的光阳极,使用含有I-/I-3氧化还原电解对的液态电解质。同时,通过原子层沉积(ALD)法,在150℃下使用三甲基铝(TMA)和水作为前驱体和氧化剂沉积氧化铝。并研究了ALD超薄氧化铝包覆二氧化锡颗粒对染料敏化太阳能电池光电转换效率的影响。椭圆偏振仪(SE)分析结果表明ALD每周期沉积速率约为1.2。X射线衍射(XRD)和场发射扫描电镜(FESEM)的结果表明,超薄氧化铝包覆没有影响多孔二氧化锡纳米晶薄膜的晶体结构和表面形貌。紫外-可见光谱(UV-Vis)研究发现随着氧化铝的沉积周期数增加,染料敏化电池光阳极吸附染料的能力增加。最后,对ALD氧化铝对染料敏化太阳能电池性能的影响机理进行了探讨。     

基于长脉冲光源的钠信标回光特性实验研究

采用与信标发射接收系统参数匹配的长脉冲光源,可在脉冲回光时间内产生较亮星等的钠信标,既有利于提高信标探测的信噪比,也有利于实现自适应光学系统的高频闭环校正.基于450 mm直径望远镜和大能量长脉冲光源,开展了钠信标探测实验,得到了长脉冲光源产生的钠信标回光特性.通过CCD和光电倍增管,采集得到了不同发射能量、出射偏振态下的回光强度,并获得了最大强度为15万光子/m2/pulse的回光,对应脉冲回光时间内约4.1等星的亮度.分析推算了实验条件下钠原子的柱密度.实验全过程未出现明显的饱和现象,验证了采用长脉冲钠信标光源避免饱和效应、得到高亮度钠信标的可行性.