Evaluating the Mobility of Nanorods in Electric Fields
Evaluating the Mobility of Nanorods in Electric Fields
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DOI：
10.1080/02786826.2013.819565
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发表时间：
2013-10-01
影响因子：
5.2
通讯作者：
Zachariah, Michael R.
中科院分区：
文献类型：
--
作者：
Li, Mingdong;You, Rian;Zachariah, Michael R.
非球形颗粒的迁移率是颗粒形状和取向的函数。反过来，电场的强度越高，非球形颗粒就越沿着电场方向排列，从而增加它们的迁移率或减小它们的迁移率直径。在之前的作品中，李埃塔尔。发展了一个一般理论的取向平均迁移率和动态形状因子适用于任何轴对称粒子在电场中，并将其应用到纳米线和球的双峰的具体情况。在这项工作中，纳米线的理论与已知形状的金纳米棒的TEM图像确定的实验结果进行了比较。我们比较实验测得的流动性的大小与理论预测的流动性在连续，自由分子，和过渡制度。基于我们的模型，在电场中的迁移率大小的变化趋势，表示在自由分子政权和过渡政权，是在很好的协议与实验结果。对于尺寸为：宽度d（r）= 17 nm和长度L-r = 270 nm，其中一个长度尺度小于平均自由程，另一个大于平均自由程，结果清楚地表明细长杆的流动状态主要由杆的直径控制（即，最小尺寸）。在这种情况下，自由分子传输特性最能代表我们的纳米棒。理论和实验相结合，我们展示了如何，通过评估的流动性作为施加电场的函数，我们可以提取杆的长度和直径。版权所有2013美国气溶胶研究协会
The mobility of a nonspherical particle is a function of both particle shape and orientation. In turn, the higher magnitude of electric field causes nonspherical particles to align more along the field direction, increasing their mobility or decreasing their mobility diameter. In previous works, Li etal. developed a general theory for the orientation-averaged mobility and the dynamic shape factor applicable to any axially symmetric particles in an electric field, and applied it to the specific cases of nanowires and doublets of spheres. In this work, the theory for a nanowire is compared with experimental results of gold nanorods with known shape determined by TEM images. We compare the experimental measured mobility sizes with the theoretical predicted mobility in the continuum, free molecular, and the transition regime. The mobility size shift trends in the electric fields based on our model, expressed both in the free molecular regime and in the transition regime, are in good agreement with the experimental results. For rods of dimension: width d(r) = 17nm and length L-r = 270nm, where one length scale is smaller than the mean free path and one larger, the results clearly show that the flow regime of a slender rod is mostly controlled by the diameter of the rod (i.e., the smallest dimension). In this case, the free molecule transport properties best represented our nanorod. Combining both theory and experiment we show how, by evaluating the mobility as a function of applied electric field, we can extract both rod length and diameter. Copyright 2013 American Association for Aerosol Research