气相色谱-双等离子体硫化学发光检测器分析天然气中硫化物

采用气相色谱-双等离子体硫化学发光检测器对天然气中的痕量硫化物进行了分析。用在线硫化物稀释装置对高浓度硫化物进行在线稀释,保证了低浓度硫化物配制的准确性,节省了购买标准样品的成本。稀释后的硫化物直接进入气相色谱仪进行分析。对方法的长期稳定性和短期稳定性进行了考察,结果表明,峰面积的RSD均小于5%,检出限达到10-9(v/v)水平。该方法适合于低浓度硫化物样品的分析检测。

等离子体诊断学介绍

等离子体诊断学是以波长在亚纳米到几十厘米范围的许多不同的物理过程为基础的。许多不同的技术正在用来测量各种等离子体参数的空间分布和演变。虽然其中大多数技术已经是非常确实的，但是等离子体诊断学仍是一门富有挑战性的活跃学科。一方面，这是始终不断地努力工作来获得更好的空间和时间分辨率、达到更高的精确度和用更多空间道测量的结果。另一方面，正在继续开发以更难以捉摸的物理过程(与在例行诊断学中使用的物理过程比)为基础的诊断技术。本文将简要介绍等离子体诊断学领域。

表面等离子共振技术及其生物传感研究进展

表面等离子共振传感器将生物学识别机制与光电装置相结合,把生物信号转化为光电信号,非常适合于对生物分子相互作用进行动态实时研究。表面等离子共振技术具有检测过程方便快捷,灵敏度高;无需标记样品,大多数情况下,不需要对样品进行处理;能在混浊的甚至不透明的样品中进行等特点。本文以表面等离子技术为基础,分析了当前应用广泛的Kretschmann模型特点,回顾和讨论了表面等离子共振传感系统的研究概况,旨在将表面等离子共振技术及相关研究成果展示给读者。

表面等离子受激辐射放大技术的研究进展

随着2009年世界最小纳米激光器实验的成功,使得越来越多的学者认为SPASER(表面等离激光)技术具备了下一代高速光电器件的特点。SPASER和目前最快的晶体管相比有同等的纳米尺度,但速度要快近千倍,且它与半导体材料应用及现行电子组件工程技术上完全兼容。本文以SPASER技术为基础,对目前发展的SPASER技术波导结构、应用情况进行了回顾和讨论,提出了引入石墨烯材料进行SPASER波导的优化方向,旨在将SPASER技术展示给更多的读者。

传导型表面等离子体激元波导结构的传播研究进展

表面等离子体激元(SPPs)是通过改变金属表面的亚波长结构实现的一种光波与可迁移的表面电荷之间电磁模,可以用来从而传输光能量,且不受衍射极限的限制。正因为SPPs这种独特的性质,使其在纳米量级操纵光能量发挥着重要的作用。当前已经产生了以SPPs研究为核心内容的亚波长光学这一学科,科学家们对此进行了广泛的研究,提出了各种的器件与机理。本文以亚波长尺度的波导结构为基础,从当前发展的较为成熟多种波导结构、应用情况对传导型表面等离子体激元的传播的研究进行了回顾和讨论,旨在将这一领域相关研究成果及发展方向展示给读者。

等离子体纳米结构Fano谐振的Q值计算研究

品质因子(Q值)是谐振模式电磁存储能力的一个重要评价指标,文中从定义出发得到了Q值的时域拟合公式,并结合时域有限差分方法对典型金属纳米结构以及Fano谐振各特征模式的Q值展开研究;此外,用较为简单方便的频域半高宽公式对上述结构进行了Q值计算.通过对比2种方法得到的结果,发现尽管频域半高宽公式能够适用于简单的金属纳米结构谐振模式Q值计算,但在处理Fano谐振的Q值时将会带来较大的误差,有时甚至极大地偏离实际值导致计算结果失去意义.文中采用的时域拟合Q值公式从谐振模式的本质出发,不受结构响应谱线型的影响,适用于各种情况下对谐振模式Q值的准确计算.

太赫兹波段表面等离子光子学研究进展

表面等离子光子学是研究金属、半导体纳米结构材料独特的光学特性,是目前光子学中最有吸引力、发展最快的领域之一.伴随着微/纳制造技术与计算机模拟技术的进步,表面等离子光子学在可见光、红外、太赫兹以及微波频域得到了广泛研究,在高灵敏生化传感、亚波长光波导、近场光学显微、纳米光刻等领域有潜在的应用价值.特别是人工超材料的发展,为自然界长期缺乏响应太赫兹波的材料和器件奠定了基础,从而也促进了太赫兹波段表面等离子光子学的研究.本文从太赫兹表面等离子波的激发、传导、最新应用及未来发展趋势等几个方面进行了回顾和讨论,将最新研究成果展示给读者.

凹槽修饰的太赫兹亚波长狭缝透射特性

为研究太赫兹波通过亚波长金属结构产生异常透射增强现象的规律,以凹槽修饰狭缝内壁的亚波长结构模型为基础,对太赫兹波段下Cu金属狭缝透射特性进行研究。依据表面等离子体理论,利用时域有限差分法对结构模型进行仿真分析。通过改变凹槽结构的几何形状,如深度、宽度、周期等参量,研究亚波长结构特征对太赫兹波透射特征调制的变化规律。研究发现,随狭缝内壁双面刻蚀矩形凹槽数目或深度的增加,太赫兹波透射明显增强,低频波段透射峰发生强度增强和峰位偏移;凹槽对称排布以及错位排布均对透射光谱有明显的调制作用。研究结果对金属亚波长结构的优化设计和新型太赫兹波功能器件的研发具有参考价值。

表面等离子体亚波长光学原理和新颖效应

表面等离子体是沿着导体表面传播的波,当改变金属表面结构时,表面等离子体激元(surface plasmon polaritons,SPPs)的性质、色散关系、激发模式、耦合效应等都将产生重大的变化.通过SPPs与光场之间相互作用,能够实现对光传播的主动操控.表面等离子体光子学(plasmonics)已成为一门新兴的学科,它的原理、新颖效应以及机制的探究,都极大地吸引研究者们的兴趣.SPPs具有广阔的应用前景,例如,应用于制作各种SPPs元器件和回路,制作纳米波导、表面等离子体光子芯片、耦合器、调制器和开关,应用于亚波长光学数据存储、新型光源、突破衍射极限的超分辨成像、SPPs纳米光刻蚀术、以及生物光学(作为传感器和探测器).文章介绍了表面等离子体光子学原理、新颖效应和物理机制,并简述若干应用.

Plasma methods for preparing green catalysts: Current status and perspective

Most current catalyst preparation methods cause pollution to air, water and land with the use of hazardous chemicals, lengthy operation time, high energy input and excessive water usage. The development of green catalyst preparation is necessary to prevent and eliminate waste from each step of the catalyst preparation. We summarize recent progress in the application of cold plasmas for green catalyst preparation. Cold plasma preparation can reduce the catalyst size, improve the dispersion and enhance catalyst-support interaction with the use of less or no hazardous chemicals. These improvements also lead to the enhancement of catalyst activity and stability. An alternative room temperature electron reduction with a non-hydrogen plasma as an electron source was developed for the reduction of noble metal ions in which no hazardous chemical reducing agent or hydrogen was needed. This creates many opportunities for the development of supported catalysts with heat sensitive substrates, including metal organic frameworks （MOFs）, covalent organic framework（COFs）, high surface area carbon, peptide, DNA, proteins and others. A novel floating metal catalyst on a water（or solution） surface has been established. Template removal using low temperature cold plasmas also leads to the formation of high surface area porous materials with characteristics that are normally only obtainable with high temperature calcination, but sintering can be avoided. Micro combustion has been developed for the removal of carbon template using cold plasma. This is promising for preparing many structured oxides in a simple way with no use of auxiliary chemicals. Many opportunities exist for the use of cold plasmas to make multi-metallic oxides. Some future development ideas are addressed.

箍缩等离子体X射线能谱诊断

为了研究和诊断箍缩聚变的聚爆靶高温等离子体内部的形状、分布及各种运动过程，基于晶体布拉格衍射，研制了新型球面弯曲晶体能谱成像系统。其核心元件是石英球面弯曲晶体（1010），弯曲半径为200mm。在中国工程物理研究院“阳”加速器上利用能谱成像系统进行了Z箍缩等离子体X射线能谱成像实验。X射线胶片得到了清晰的钛等离子体X射线能谱成像信息。对实验所得能谱信息进行分析，石英球面弯曲晶体得到等离子体X射线的能谱分辨率约为1092，与X射线能谱分辨几何模型理论值比较吻合。实验结果表明石英球面弯曲晶体可以用于X射线的能谱诊断。

金属粒子阵列共振的偏振特性

当金属纳米粒子形成规则分布且阵列周期与单粒子的共振波长近似匹配时,会形成一种特殊的阵列共振,这种共振比单粒子的局域表面等离子体共振具有更窄的共振线宽和更高的共振强度.基于修正的长波近似方法,讨论了矩形阵列的消光截面与阵列因子和单粒子的极化率之间的关系;并详细研究了在不同偏振的入射光照射下,阵列因子随着电偶极子方向的改变而产生的变化,以及这一效应对阵列共振和消光截面所产生的影响.结果表明,大型的方阵是偏振无关的;在矩形阵列中,沿着阵列两个轴向的相邻粒子之间的耦合形成了阵列因子的两个极值,并且分别对应了散射截面的最小值.

Doped-Chamber Deposition of Intrinsic Microcrystalline Silicon Thin Films and Its Application in Solar Cells

A series of microcrystalline silicon thin films were fabricated by very high frequency plasma enhanced chemical vapor deposition （VHF-PECVD） at different silane concentrations in a P chamber. Through analysis of the structural and electrical properties of these materials,we conclude that the photosensitivity slightly decreased then increased as the silane concentration increased,while the crystalline volume fraction indicates the opposite change. Results of XRD indicate that thin films have a （220） preferable orientation under certain conditions. Microcrystalline silicon solar cells with conversion efficiency 4. 7% and micromorph tandem solar cells 8.5% were fabricated by VHF-PECVD （p layer and i layer of microcrystalline silicon solar cells were deposited in P chamber）, respectively.

Microstructure and mechanical properties of Ti-43Al-9V alloy fabricated by spark plasma sintering

A fine-grained TiAl alloy with the composition of Ti-43Al-9V was prepared by mechanical milling and spark plasma sintering（SPS）.The relationship among sintering temperature,microstructure and mechanical properties was studied.The results show that the morphology of mechanical milling powder is regular with size in a range of 5-30 μm.Main phases of γ-TiAl,α2-Ti3Al and few B2 phase are observed in the SPS bulk samples.For samples sintered at 1150 °C,equiaxed crystal grain microstructure is achieved with size in a range of 300 nm-1 μm.With increasing SPS temperature to 1250 °C,the size of equiaxed crystal grains obviously increases,the microhardness decreases from HV592 to HV535,and the bending strength decreases from 605 to 219 MPa.Meantime,the compression fracture strength also decreases from 2601 to 1905 MPa,and the strain compression decreases from 28.95% to 12.09%.

Effect of spark plasma sintering temperature on microstructure and mechanical properties of melt-spun TiAl alloys

A TiAl alloy from pulverized rapidly solidified ribbons with the composition of Ti-46Al-2Cr-4Nb-0.3Y（mole fraction,%） was processed by spark plasma sintering（SPS）.The effects of sintering temperature on the microstructure and mechanical properties were studied.The results show that the microstructure and phase constitution vary with sintering temperature.Sintering the milled powders at 1200 ℃ produces fully dense compact.Higher sintering temperature does not improve the densification evidently.The dominant phases are γ and α2 in the bulk alloys sintered at 1200 ℃.With higher sintering temperature,the fraction of α2 phase decreases and the microstructure changes from equiaxed near γ grain to near lamellar structure,together with a slight coarsening.The bulk alloy sintered at 1260 ℃ with refined and homogeneous near lamellar structure reveals the best overall mechanical properties.The compressional fracture stress and compression ratio are 2984 MPa and 41.5%,respectively,at room temperature.The tensile fracture stress and ductility are 527.5 MPa and 5.9%,respectively,at 800 ℃.

Microstructure and mechanical properties of TiAl-based alloy prepared by double mechanical milling and spark plasma sintering

A fine-grained TiAl alloy with a composition of Ti-45Al-2Cr-2Nb-1B-0.5Ta-0.225Y （mole fraction, %） was prepared by double mechanical milling（DMM） and spark plasma sintering（SPS）. The relationship among sintering temperature, microstructure and mechanical properties was studied. The results show that the morphology of double mechanical milled powder is regular with size in the range of 20-40 μm and mainly composed of TiAl and Ti3Al phases. The main phase TiAl and few phases Ti3Al, Ti2Al and TiB2 were observed in the SPSed alloys. For samples sintered at 900 ℃ the equiaxed crystal grain microstructure is achieved with size in the range of 100-200 nm. With increasing the SPS temperature from 900 ℃to 1000 ℃ the size of equiaxed crystal grain obviously increases, the microhardness decreases from HV658 to HV616, and the bending strength decreases from 781 MPa to 652 MPa. In the meantime, the compression fracture strength also decreases from 2769 MPa to 2669 MPa, and the strain to fracture in compression increases from 11.69% to 17.76%. On the base of analysis of fractographies, it shows that the compression fracture transform of the SPSed alloys is intergranular rupture.

Fabrication of Hydrogenated Microcrystalline Silicon Thin Films at Low Temperature by VHF-PECVD

Using H 2 diluted silane,series of μc Si∶H films are fabricated at low temperature with VHF PECVD.The thickness measurements reveal that the deposition rates are obviously enhanced with higher plasma excitation frequency or working pressure,but increase firstly and then decrease with the increase of plasma power density.Raman spectra show that the crystallinity and the average grain sizes of the films strongly depend on the temperature of substrate and the concentration of silane.However,the plasma excitation frequency only has effect on the crystallinity,and a maximum occurs during the further increase of plasma excitation frequency.From XRD and TEM experiments,three preferential crystalline orientations (111),(220) and (311) are observed,and the average grain sizes are different for every crystalline orientation.

自参考磁流体磁场传感器研究

基于磁流体的光学特性,提出一种自参考塔姆等离子体激元混合模磁场传感器。该传感结构由两个金属-分布式布拉格反射器结构和嵌于二者之间的用于感应外磁场的磁流体层构成。研究表明,该传感结构可激发两个塔姆等离子体激元。在一定的结构参数下,其中一个基本不随外磁场的改变而发生变化,而另一个对外磁场非常敏感。数值结果表明,该传感结构的探测灵敏度要优于已报道的采用单层磁流体作为传感层的光子晶体磁场传感器。研究结果为磁流体磁场传感器的设计制备提供了参考。

Microstructure characteristics and mechanical properties of TiB/Ti-1.5Fe-2.25Mo composites synthesized in situ using SPS process

TiB/Ti-1.5Fe-2.25Mo composites were synthesized in situ using the spark plasma sintering （SPS） method at temperatures of 850-1150 °C. The effect of the sintering temperature on microstructure and mechanical properties of the composites was investigated. The results indicate that the aspect ratio of the in situ synthesized TiB whiskers in Ti alloy matrix decreases rapidly with an increase in sintering temperature. However, both the relative density of the sintered specimens and the volume content of TiB whiskers in composites increase with increasing sintering temperature. Thus, the bending strength of the composites synthesized using SPS process increases slowly with increasing the sintering temperature from 850 to 1150 °C. TiB/Ti-1.5Fe-2.25Mo composite synthesized at 1150 °C using SPS method exhibits the highest bending strength of 1596 MPa due to the formation of fine TiB whiskers in Ti alloy matrix and the dense microstructure of the composite.

MIM结构的SPP模式理论与仿真计算研究

为了进一步明确MIM(Metal-insulator-metal)波导结构的SPP(Surface plasmon polariton)模式特性,建立了MIM结构的SPP模式关系、激发系数和反射系数的理论模型。仿真数值计算结果表明:较大的介质厚度的TM基态模式衰减超过了振荡模式衰减,与传统的介质波导明显不同;TE模式表现为失真的介质光波导模式特性,其传播距离要远大于TM0;MIM结构中腔的Q值随着长度增加而增大,表明了SPP反射受限;腔的品质因数改变与端面关系密切;MIM波导可以在具有更大Q值下确保光波更好地耦合成需要的SPP模式。