Getfert Sebastian, Töws Thomas, Reimann Peter
Fakultät für Physik, Universität Bielefeld, 33615 Bielefeld, Germany.
Phys Rev E Stat Nonlin Soft Matter Phys. 2013 Nov;88(5):052710. doi: 10.1103/PhysRevE.88.052710. Epub 2013 Nov 15.
We consider the translocation of a neutral (uncharged) nanoparticle through a pore in a thin membrane with constant surface charge density. If the concomitant Debye screening layer is sufficiently thin, the resulting forces experienced by the particle on its way through the pore are negligible. But when the Debye length becomes comparable to the pore diameter, the particle encounters a quite significant potential barrier while approaching and entering the pore, and symmetrically upon exiting the pore. The main reason is an increasing pressure, which acts on the particle when it intrudes into the counter ion cloud of the Debye screening layer. In case the polarizability of the particle is different (usually smaller) than that of the ambient fluid, a second, much smaller contribution to the potential barrier is due to self-energy effects. Our numerical treatment of the problem is complemented by analytical approximations for sufficiently long cylindrical particles and pores, which agree very well with the numerics.
我们考虑一个中性（不带电）纳米粒子通过具有恒定表面电荷密度的薄膜中的孔隙的迁移情况。如果伴随的德拜屏蔽层足够薄，那么粒子在穿过孔隙过程中所受到的合力可以忽略不计。但是，当德拜长度与孔隙直径相近时，粒子在接近并进入孔隙以及对称地在离开孔隙时会遇到相当大的势垒。主要原因是当粒子侵入德拜屏蔽层的反离子云时，作用在粒子上的压力会增加。如果粒子的极化率与周围流体不同（通常较小），那么对势垒的第二个小得多的贡献是由于自能效应。对于足够长的圆柱形粒子和孔隙，我们用解析近似对该问题进行了数值处理，解析近似与数值结果非常吻合。
