排序方式: 共有68条查询结果,搜索用时 0 毫秒
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By applying polystyrene opals made by a vertical deposition method as the templates, a modified filling method and a well-controlled calcination process, we have successfully obtained a large-area ordered TiO2 inverse opal with a higher vo]ume fraction (14.5%) and a visib]e photonic bandgap. The influences of the fi]]ing process and calcination conditions on the fabrication of the TiO2 inverse opal are investigated. 相似文献
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采用两步法合成了直径分别为782,977,1027,1160和1324nm的SiO2胶体颗粒,透射电子显微镜显示颗粒尺寸的平均标准偏差小于5%.具有较好的单分散性.通过调节SiO2胶体颗粒悬浮液中介质粘度的方法,拓宽了重力沉降自组装的尺寸范围,得到了颗粒直径为700—1300nm的合成蛋白石 ,扫描电子显微镜图像显示它们为面心立方结构,透射谱表征显示它们具有一定的光子带隙.
关键词:
SiO2胶体颗粒
重力沉降自组装
合成蛋白石
光子带隙 相似文献
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Under illumination of excitation light, the force that can make fluorescent dye-labelled microtubules break up is measured by using dual-beam optical tweezers. It is found that this force is about several piconewtons, which is two orders of magnitude smaller than that without fluorescence label. Microtubules can be elongated about 20% and the increase of the tensile force is nonlinear with the microtubule elongation. Some qualitative explanations are given for the mechanisms about the breakup and elongation of microtubules exposed to excitation light. 相似文献
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Antimonite and cryolite are used as the high and low refractive index coating materials to be evaporated alternately to the glass substrates. All cryolite layers have the same thickness d/4na, and the thickness of antimonite layers varies randomly around an average value d/4nb, with d=650nm, na and nb their refractive indices. Three kinds of multilayer are prepared, they possess the same degree of thickness disorder, but different total lengths, i.e., 10, 15 and 21 perioda. We measure the transmission and reflection spectrum after the light passing through these multilayers. The exponential intensity variation versus total length is experi-mentally demonstrated, and the light localization length is then obtained. Our experimental results can be fitted very well with the numerical simulation. Based on the measured and calculated localization length, the effects of phase coherent: Bragg reflection and Anderson localization are discussed. 相似文献
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利用外加电场极化的方法,分别研究了三种不同方式布置的极化电极对C向切割LiNbO3< /sub>晶体极化反转畴扩张的影响.实验结果表明在相同极化条件下,当极化电极长度方向与六边 形反转畴一对边呈90°和0°角时,极化扩张速度分别为0.089μm/ms和0.011μm/ms.实验结果揭示,为了有效地控制极化占空比,在制备一维准相位匹配LiNbO3晶体时应 避免极化电极与六边形反转畴壁中一对边呈90°的情况.
关键词:
周期极化
极化扩张
准相位匹配 相似文献
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苏黎世IBM实验室Hans Werner Fink和他的研究组研制出一种全息电子显微镜,首次为生物学家开辟了可观察生命的微秒级化学过程的新途径.这种显微镜用的是钨针尖电子源.针尖仅有一个原子大小,它发射具有类似激光特征的电子束,利用它能进行延续仅100ns的三维快速摄影. 常规电子显微镜与光学显微镜工作原理相同,电子束射经物体后由透镜加以放大.遗憾的是生物学家以前所能用的电子显微镜电子能量高达150keV.电子带有如此高的能量不仅会损坏样品,而且能直接穿过碳原子而不被它散射,因此不能对碳为基础的分子成象.为此,DNA和其他有机分子的样品… 相似文献
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一般情况下,惰性气体不易与其他元素或本身发生化学反应.然而,英国Sussex大学的两位化学家 Poul Lethbridge 和 Tony stace制成了含有多至340个氪原子的原子基团或簇(Journal of Chemical Physics,vol.91,p.7685).这一结果填补了分子体系和体材料之间的空白.这种结构对研究催化作用很有意义. 制造原子簇的过程为:让气态氪通过一直径为200μm的小孔射入真空室.经过喷射冷却的氪原子相互碰撞,弱的范德瓦耳斯力,不断地使碰撞的原子聚集在一起,形成一定结构的基团.制成的基团原子数在10至340之间.研究人员先用电子束将基团离化,再用质谱仪分… 相似文献
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Measurements of displacement and trapping force on micron-sized particles in optical tweezers system
A high-stability optical tweezers equipped with a high-precision measurement system of displacement and force is set up. The
results show that this combination can be used to carry out quantitative measurements of small displacements and forces for
micron-sized spheres. The precision of measurements has reached nanometers and piconewtons, respectively. 相似文献