排序方式: 共有22条查询结果,搜索用时 212 毫秒
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采用APPLEⅡ微机控制9W测微光密度计,实现对谱板自动化测量。论述了该系统的工作原理、主要功能和特性。给出了使用该系统所测得的实际光谱谱图。 相似文献
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The transverse trapping forces on a dielectric sphere located at an oil-water interface are theoretically investigated with the ray-optics model. The transverse trapping forces rely on the internal property of the particle-interface system, and increase with either the decrease of three phase contact angles at the oil- water interface or the use of oil phase with low refractive index. The numerical results also show that the transverse trapping forces can be improved by either decreasing the numerical aperture of the microscope objective or shrinking the diameter of the trapping laser beam. 相似文献
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Observing Nanometre Scale Particles with Light Scattering for Manipulation Using Optical Tweezers 下载免费PDF全文
Nanometre-scale particles can be manipulated using optical tweezers, but cannot be directly observed. We present a simple method that nanoparticles can be directly observed using optical tweezers combined with dark field microscopy. A laser beam perpendicular to a tightly focused laser beam for trap illuminates specimen and does not enter objective, nanoparticles in focal plane all can be directly observed in dark field because of light scattering. It is implemented that the polystyrene beads of diameter lOOnm can be directly observed and trapped. 相似文献
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像差会影响光镊对粒子的捕获效果. 全息阵列光镊中, 像差不仅来自光学元件, 由特定算法设计的光阱相位片也会在光路中引入像差. 本文通过液晶空间光调制器加载泽尼克多项式相位图, 对全息阵列光镊中由光栅透镜组型算法引起的像差进行校正. 结果显示: 利用三阶泽尼克多项式可有效消除光路中由光栅透镜组型算法引 起的慧差, 使得捕获2 μm聚苯乙烯小球的阵列光阱刚度提高了约40%; 对比不同项的像差校正结果发现, 全息阵列光镊中由算法引起的慧差 与光学元件引起的像差一样, 也会对阵列光阱的捕获效果产生较大影响; 同时根据一阶像差校正结果可得光栅透镜 组型算法对于一阶泽尼克像差具有鲁棒性. 实验结果表明, 对全息阵列光镊中由 算法引起的像差进行校正, 对于提高光阱的捕获效果和深化对算法特性的认识都具有重要意义. 相似文献
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Since RGD peptides (R: arginine; G: glycine; D: aspartic acid) are found to promote cell adhesion, they are modified at numerous materials surface for medical applications such as drug delivery and regenerative medicine. Peptide-cell surface interactions play a key role in the above applications. In this letter, we study the adhesion force between the RGD-coated bead and Hela cell surface by optical tweezes. The adhesion is dominated by the binding of α5β1 and RGD-peptide with higher adhesion probability and stronger adhesion strength compared with the adhesion of bare bead and cell surface. The binding force for a single α5β1 -GRGDSP pair is determined to be 16.8 pN at a loading rate of 1.5 nN/s. The unstressed off-rate is 1.65 × 10-2s-1 and the distance of transition state for the rigid binding model is 3.0 nm. 相似文献
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高分子添加剂对激光染料荧光的增强效应 总被引:1,自引:0,他引:1
本文研究以水作溶剂的Rh-6G激光染料中加入高分子添加剂——聚乙二醇(分子量为6000)引起的染料荧光的增强效应。通过荧光光谱,吸收光谱与染料浓度,添加剂含量的关系的实验研究,定量地给出了不同添加剂量对荧光的增强作用。表明了荧光增强效应的机理主要是添加剂抑制了二聚物的形成。 相似文献
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Optical tweezers have been successfully used in the study of colloid science. In most applications people are concerned with the behaviour of a single particle held in the optical tweezers. Recently, the ability of the optical tweezers to simultaneously hold two particles has been used to determine the stability ratio of colloidal dispersion. This new development stimulates the efforts to explore the characteristics of a two-particle system in the optical tweezers.An infinite spherical potential well has been used to estimate the collision frequency for two particles in the optical trap based on a Monte Carlo simulation. In this article, a more reasonable harmonic potential, commonly accepted for the optical tweezers, is adopted in a Monte Carlo simulation of the collision frequency. The effect of hydrodynamic interaction of particles in the trap is also considered. The simulation results based on this improved model show quantitatively that the collision frequency drops down sharply at first and then decreases slowly as the distance between the two particles increases. The simulation also shows how the collision frequency is related to the stiffness of the optical tweezers. 相似文献