Observation of Ordered Structures in Counterion Layers near Wet Charged Surfaces: A Potential Mechanism for Charge Inversion
Observation of Ordered Structures in Counterion Layers near Wet Charged Surfaces: A Potential Mechanism for Charge Inversion
复制标题
湿带电表面附近反离子层有序结构的观察：电荷反转的潜在机制
DOI：
10.1021/acs.langmuir.5b04058
复制
发表时间：
2015
期刊：
影响因子：
3.9
通讯作者：
Dutta, Pulak
中科院分区：
文献类型：
--
作者：
Miller, Mitchell;Chu, Miaoqi;Lin, Binhua;Meron, Mati;Dutta, Pulak
水溶液中的带电（如胶体）粒子有时会表现为它们的有效电荷被吸引的反离子逆转而不是减少。这是违反直觉的，因为它增加了静电能量，但有人提出，离子的横向排序可以降低自由能，有利于过充电（电荷反转）。利用x射线衍射，我们在漂浮分子单层形成的带电表面附近观察到不匹配的Er3+反离子单层的尖锐衍射峰。当反离子晶格与分子表面晶格不匹配时，这意味着没有离子的特异性附着，因此离子晶格是由于反离子层中电荷之间的相互作用而形成的。因此，不相称格的存在表明逆序是一种现实的机制。然而，在这个系统中，我们的数据排除了一个众所周知的“物理”机制由库仑相互作用驱动的维格纳液相。
Charged (e.g., colloidal) particles in aqueous solutions will sometimes behave as though their effective charge has reversed, rather than reduced, by the attracted counterions. This is counterintuitive because it increases the electrostatic energy, but it has been proposed that lateral ordering of the ions could lower the free energy and favor overcharging (charge inversion). Using X-ray diffraction, we have observed sharp diffraction peaks from incommensurate Er3+counterion monolayers near charged surfaces formed by floating molecular monolayers. When the counterion lattice does not match the molecular surface lattice, this means that there is no specific attachment of ions, and thus the ionic lattice is formed due to interactions between charges in the counterlayer. Therefore, the existence of incommensurate ion lattices indicates that counterion ordering is a realistic mechanism. However, in this system our data rule out a well-known proposed “physical” mechanismthe Wigner liquid phase driven by Coulomb interactions.