Aerodynamic focusing of nanoparticles: I. Guidelines for designing aerodynamic lenses for nanoparticles
Aerodynamic focusing of nanoparticles: I. Guidelines for designing aerodynamic lenses for nanoparticles
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DOI：
10.1080/02786820500181901
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发表时间：
2005-07-01
影响因子：
5.2
通讯作者：
McMurry, PH
中科院分区：
文献类型：
--
作者：
Wang, XL;Kruis, FE;McMurry, PH
本文描述了将纳米颗粒（< 30 nm）聚焦成紧密准直光束的挑战，并为设计纳米颗粒的空气动力学透镜系统提供指导。聚焦纳米粒子的主要困难来自于它们的低惯性和高扩散性。由于它们的低惯性，纳米颗粒倾向于紧密地跟随气体流线;它们的高扩散率导致光束加宽和扩散沉积。假设流动是连续的且亚音速的，我们已经确定了当忽略扩散时可以用单个透镜聚焦到轴上的最小颗粒尺寸。我们表明，较轻的载气是首选的小颗粒的聚焦，并在次优斯托克斯数操作的多个镜头可以被设计为聚焦粒子小于以前被认为是。存在最大压力，在该最大压力下，颗粒可以最佳地聚焦，同时颗粒扩散和泵送要求被最小化。最后，我们描述的空气动力学透镜系统的设计过程中聚焦纳米粒子，并提出了一个案例研究设计一个单一的空气动力学透镜，以重点5 nm的颗粒。
This article describes the challenges in focusing nanoparticles (< 30 nm) into tightly collimated beams, and provide guidelines for designing aerodynamic lens systems for nanoparticles. The major difficulties of focusing nanoparticles arise from their low inertia and high diffusivity. Because of their low inertia, nanoparticles tend to closely follow gas streamlines; their high diffusivities lead to beam broadening and diffusional deposition. We have identified the minimum particle size that can be focused to the axis with a single lens when diffusion is neglected, assuming that the flow is continuum and subsonic. We show that lighter carrier gases are preferred for focusing small particles, and that multiple lenses operating at suboptimal Stokes numbers can be designed to focus particles smaller than was recognized previously. There exists a maximum pressure under which particles can be optimally focused, while particle diffusion and pumping requirements are minimized. Finally, we describe the procedure for designing aerodynamic lens systems for focusing nanoparticles, and present a case study of designing a single aerodynamic lens to focus 5 nm particles.