金纳米颗粒的有序制备及其光学特性

采用纳米球蚀刻技术在石英衬底上制备了不同高度的金纳米颗粒阵列.通过扫描电子显微镜对其表面形貌进行了观测,表明金纳米颗粒为有序分布的三棱柱结构.通过红外—紫外吸收光谱仪在190—900nm波长范围内对其光吸收特性进行了测量, 并成功观测到了金纳米颗粒表面等离子体振荡效应引起的光吸收峰,结果表明随着金纳米颗粒高度的增加,其吸收峰的位置向短波方向移动(蓝移).同时对金纳米颗粒的光吸收特性进行了基于离散偶极子近似的理论计算,并与实验结果进行了比较. 关键词： 纳米球蚀刻技术 金纳米颗粒 离散偶极子近似     

Au纳米颗粒阵列中双光子吸收的饱和过程

采用纳米球蚀刻法制备了Au纳米颗粒阵列.并通过扫描电子显微镜观测了其表面形貌,表明三角形的Au纳米颗粒呈阵列状分布.采用Z扫描方法(800 nm, 50 fs)测量了Au纳米颗粒阵列的三阶非线性光学特性.在较小的激发功率下,结果呈现出双光子吸收效应,随着激发功率不断增加,出现了双光子吸收饱和的过程;非线性折射则呈现出自散焦效应.这种高效率的非线性响应机理使得该种Au纳米颗粒阵列在高速全光开关中有潜在的应用价值. 关键词： 纳米球蚀刻技术 Au纳米颗粒 三阶光学非线性     

衍射光学元件的反应离子束蚀刻研究

本文提出了一种制作衍射光学元件的新方法——-反应离子束蚀刻法.对此技术研究的结果表明:反应离子束蚀刻法具有高蚀刻速率、蚀刻过程各向异性好、蚀刻参数控制灵活等特点,对于衍射光学元件和微光学元件的精细结构制作十分有利.本文详细总结了反应离子束蚀刻过程中各工艺参数对蚀刻速率的影响,并在红外材料上制作了Dammann分束光栅.     

纳米孔径核孔模的制备研究

高能硫、氪、氙离子轰击聚酯（PET）和聚碳酸酯（PC）膜后,对样品进行陈化和紫外线照射敏化。用电导法着重研究蚀刻条件对样品的归一化径迹蚀刻速率（灵敏度）的影响,结果表明优化条件下灵敏度较通用条件下提高约2倍,PET的灵敏度可达1000,PC的灵敏度可达2000,可以用于制备纳米孔径核孔膜。核孔膜中填充的铜纳米线的电镜照片显示出纳米线最小直径为20nm。用电导法计算纳米孔的孔径,该值与纳米线直径的电镜测量值在孔径大于30nm时符合良好。     

纳米孔径核孔膜的制备研究

高能硫、氪、氙离子轰击聚酯(PET)和聚碳酸酯(PC)膜后，对样品进行陈化和紫外线照射敏化．用电导法着重研究蚀刻条件对样品的归一亿径迹蚀刻速率(灵敏度)的影响，结果表明优化条件下灵敏度较通用条件下提高约2倍，PET的灵敏度可达1000，PC的灵敏度可达2000，可以用于制备纳米孔径核孔膜．核孔膜中填充的铜纳米线的电镜照片显示出纳米线最小直径为20nm．用电导法计算纳米孔的孔径，该值与纳米线直径的电镜测量值在孔径大于30nm时符合良好．     

RIE精确传递微光学三维结构于红外材料的方法

本文对红外光学材料锗的蚀刻性能、机制进行了深入的研究,在反应离子蚀刻(RIE)实验基础上,建立了锗材料蚀刻性能与RIE工艺参量的关系,经过大量的实验,找到了稳定蚀刻速率的方法和条件,为用RIE技术形成高精度衍射微光学元件积累了实用经验.     

RIE精确传递微光学三维结构于红外材料的方法

本文对红外光学材料锗的蚀刻性能、机制进行了深入的研究,在反应离子蚀刻(RIE)实验基础上,建立了锗材料蚀刻性能与RIE工艺参量的关系,经过大量的实验,找到了稳定蚀刻速率的方法和条件,为用RIE技术形成高精度衍射微光学元件积累了实用经验.     

硅衬底上纳米晶金刚石生长

研究了蚀刻气体对生长在硅衬底上纳米晶金刚石合成的影响.合成方法为热丝化学气相沉积法,衬底温度为550 oC,反应压力为4 kPa. 其中甲烷和氢气分别作为源气体和稀释气体. 氮气、氢气和氨气用作蚀刻气体. 结果表明,仅氢气作为蚀刻气体可获得最佳工艺条件.     

冷冻电镜单颗粒技术的发展、现状与未来

近年来冷冻电子显微镜成像技术突飞猛进,越来越广泛地应用于生物大分子的高精度结构研究中,尤其在解析其他方法难以应对的蛋白质复合物的结构研究方面取得了瞩目的进展。文章对冷冻电镜单颗粒重构技术近年来的发展做了回顾和总结,重点介绍了冷冻电镜单颗粒重构技术中的基本流程及其使用的图像处理技术和算法,并对近年来人们重点关注的问题进行了讨论。最后对冷冻电镜单颗粒重构技术未来的发展趋势,尤其是对细胞内原位的分子结构以及蛋白质分子的动态信息的捕捉等方面进行了初步的探讨。     

蚀刻表面面形的分析

采用一个有效的数学模型,分析了在蚀刻工艺中基底自身面形轮廓的曲线形状对基底局部区域的蚀刻速率产生的影响,并通过对数学模型的理论分析和计算机模拟得出受此影响而产生的面形形状,并将结果与实验进行对比.利用这个数学模型对使用离子束蚀刻制作单台阶光栅的台阶与沟槽部分的表面面形随时间的演变过程进行了计算机模拟分析,并通过把理论结果与在实验中得到的蚀刻表面在原子力显微镜(AFM)下拍摄的照片进行比较,结果说明这种模拟分析能够保证对该问题分析所要求的精度,从而也证明了理论模型的合理性和正确性.     

Hybridization of surface-modified metal nanoparticles and a resin

Mercapto-terminated linear polymers, which were prepared by a reversible addition-fragmentation chain transfer (RAFT) technique, were used to modify metal nanoparticle surfaces. Au and Ag nanoparticles which are approximately 3–6 nm were used. This modification resulted in easy dispersion of the nanoparticles in polymer resins by simple mixing. The quality of the dispersion was confirmed by UV–Vis spectroscopy and transmission electron microscopy.     

Gas-phase preparation and size control of Fe nanoparticles

The magnetic, electrical and optical properties of nanoparticle systems often depend on the size and size distribution of nanoparticles. In order to optimize those properties of nanoparticle-assembled materials, only varying the mean size of nanoparticles was not enough, and narrowing the size distribution was also of immense importance. In this study, uniform-sized Fe nanoparticles with different diameters were prepared using a magnetron sputtering combined with inert gas condensation technique. The size and morphology of nanoparticles were observed by transmission electron microscopy (TEM). The statistic results revealed that the size of Fe nanoparticles increased with increasing the flow rate of Ar gas, but a reverse trend was observed when increasing the flow rate of He gas. By adjusting the flow rate of Ar and He gases, uniform-sized Fe nanoparticles with diameter ranging from 6 to 13?nm were obtained. Moreover, the size effects on the electrical and magnetic properties of Fe nanoparticle-assembled films with thickness of about 500?nm were also investigated. The magnetic properties showed that the coercivity increased with increasing the nanoparticle size. The in-situ resistance measurement results of Fe nanoparticle assembled-films also showed a size-dependent behavior.     

In situ electron beam irradiated rapid growth of bismuth nanoparticles in bismuth-based glass dielectrics at room temperature

In this study, in situ control growth of bismuth nanoparticles (Bi⁰ NPs) was demonstrated in bismuth-based glass dielectrics under an electron beam (EB) irradiation at room temperature. The effects of EB irradiation were investigated in situ using transmission electron microscopy (TEM), selected-area electron diffraction and high-resolution transmission electron microscopy. The EB irradiation for 2–8 min enhanced the construction of bismuth nanoparticles with a rhombohedral structure and diameter of 4–9 nm. The average particle size was found to increase with the irradiation time. Bismuth metal has a melting point of 271 °C and this low melting temperature makes easy the progress of energy induced structural changes during in situ TEM observations. This is a very useful technique in nano-patterning for integrated optics and other applications.     

Characterisation of colloidal drug delivery systems from the naked eye to Cryo-FESEM

Poly(ethylcyanoacrylate) nanoparticles prepared by interfacial polymerisation on the basis of microemulsions were prepared in this study and both colloidal systems, nanoparticles and microemulsions, were analysed by visual observation and several microscopic techniques. Phase boundaries for the microemulsions of the two pseudoternary systems ethyloleate, polyoxyethylene 20 sorbitan mono-oleate/sorbitan monolaurate and water with and without butanol as a cosurfactant were determined by visual observation of the samples. Microemulsions containing liquid crystals were determined by polarisation light microscopy. Using freeze-fracture transmission electron microscopy and Cryo-field emission scanning electron microscopy the type of microemulsion (w/o droplet, bicontinuous, solution) was characterised. Nanoparticles prepared from the different types of microemulsion were additionally observed by conventional scanning electron microscopy. The size of the nanoparticles obtained from electron microscopy was in good agreement with particle sizing techniques (photon correlation spectroscopy) from earlier studies and no morphological differences could be observed in particles prepared from the different types of microemulsions. Cryo-field emission scanning electron microscopy proved to be a most valuable technique in the visualisation of the colloidal systems as samples could be observed close to their natural state.     

Fabrication and Tribological Properties of Pb Nanoparticles

In this paper, we describe a surfactant-assisted solution dispersion method to obtain metal nanoparticles, which involves dispersing and stabilizing metal droplets in an appropriate solvent. This method has been successfully used to prepare Pb nanoparticles from bulk Pb. The X-ray powder diffraction and transmission electron microscopy investigations show the formation of Pb nanoparticles possessing the same crystal structure as bulk metal and an average particle diameter of 40 nm. Thermal analysis indicates that Pb nanoparticles have organic shell, which is in agreement with the excellent oil-solubility. In addition, the tribological properties of Pb nanoparticles as additive in oil are discussed.     

Nanocomposite Ni–TiN coatings prepared by ultrasonic electrodeposition

Nanocomposite Ni–TiN coatings were prepared by ultrasonic electrodeposition and the effects of ultrasonication on the coatings were studied. X-ray diffraction analysis was utilized to detect the crystalline and amorphous characteristics of the composite coatings. The surface morphology and metallurgical structure were observed by scanning electron microscopy, high-resolution transmission electron microscopy and scanning probe microscopy. The results showed that ultrasonication had great effects on TiN nanoparticles in composite coatings. The moderate ultrasonication conduced to homogeneous dispersion of TiN particles in the coatings. Moreover, the TiN nanoparticles that entered and homogeneously dispersed in the composite coating led to an increase in the number of nuclei for nucleation of nickel grains and inhibition of grain growth. Therefore, the introduction of ultrasonication and TiN nanoparticles resulted in the formation of smaller nickel grains. The average grain diameter of TiN particles was ∼33 nm, while Ni grains measured approximately 53 nm.     

Observation of the diameter-dependent Raman dispersion effect in chemically oxidized multiwalled carbon nanotubes

Chemical oxidation of multiwalled carbon nanotubes (MWCNTs) using H₂SO₄/HNO₃ solution has been monitored by micro-Raman spectroscopy and X-ray absorption spectroscopy. The diameter distribution variation in MWCNTs due to chemical oxidation has been measured by scanning electron microscopy and transmission electron microscopy. The Raman dispersion behaviors of the intensity ratio and the band positions of the D, G, and G′ bands were found to be correlated with the MWCNT diameter distribution. It was also found that, during the nanotube unzipping process, defect formation complicates the observation of the diameter-dependent Raman dispersion effect. The curvature effect plays an important role in the intensity ratio trend. On the other hand, defect formation dominates the band position trend.     

埃洛石纳米管负载Ni纳米粒子的研究

以天然纳米管埃洛石为载体,以Sn-Pd胶体溶液作为活化剂,利用化学镀法在埃洛石的内表面镀金属Ni。利用XRD、TEM对合成的产物进行分析表征,表明在埃洛石纳米管的内腔沉积了颗粒连续、尺寸大小约为10nm的Ni粒子,而HRTEM分析表明Ni微粒为纳米晶体。良好分散性能的镍-埃洛石纳米复合材料将会在高效催化剂、润滑剂、传感器,高密度磁记录材料等领域有潜在的应用前景。     

聚合物表面银纳米颗粒的大面积均匀沉积及其应用

通过化学浸润和光还原法在聚合物薄膜基片（三醋酸纤维树酯）上直接沉积制备出大面积范围内颗粒大小、表面密度等分布均匀的纳米金属银颗粒.紫外吸收光谱和高分辨透射电镜分析表明，在室温实验条件下调整化学溶液浓度，可获得颗粒直径在2—5nm范围内的球形金属纳米银颗粒.通过接触拷贝方式，获得了基于银纳米颗粒形成的全息光栅. 关键词： 银纳米颗粒 聚合物薄膜 浸润 光还原     

铅纳米微粒用作油性润滑的摩擦学性能研究

在石蜡油 聚乙二醇的混合溶剂中 ,通过液相分散法成功地制备出了铅纳米微粒 .其中 ,石蜡油是反应介质 ,聚乙二醇是抗氧化剂 .同时 ,对铅纳米微粒的形貌和结构进行了透射电镜 (TEM)和X光衍射 (XRD)表征 .结果表明 ,铅纳米微粒呈球形 ,平均粒径为 70nm ,具有与本体铅相同的晶体结构 .另外 ,在四球试验机上表征了铅纳米微粒作为润滑油添加剂的摩擦学性能 .摩擦试验表明 ,铅纳米微粒具有良好的减摩抗磨性能 ,并能够显著改善基础油的承载能力 .磨斑表面分析表明 ,铅纳米微粒的抗磨减摩机制不是形成金属沉积膜 ,可能是在摩擦接触面形成滑动 轴承系