胶体导体表面静电作用

单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,*,Colloidal electrostatic interactions near a conducting surface胶体导体表面的静电作用Marco Polin,1 David G. Grier,1 and Yilong Han21Center for Soft Matter（软物质） Research, New York University, 4 Washington Place, New York, New York 10003, USA2Department of Physics, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong KongReceived 2 May 2006; revised manuscript（手稿修订） received 19 July 2007; published 30 October 2007,园堂窄扩筷备媳搐官伴吁裴刮檄欢年逸量杜挞呆膀孵谐褥胳缉劲龋堤胶携胶体导体表面静电作用胶体导体表面静电作用,Like-charged colloidal spheres dispersed in de-ionized water are,supposed to repel each other. Instead, artifact-corrected video,microscopy measurements reveal an anomalous long-ranged like-charge,attraction in the interparticle pair potential when the spheres are,confined to a layer by even a single-charged glass surface. These,attractions can be masked by electrostatic repulsions at low ionic,strengths. Coating the bounding surfaces with a conducting gold layer,suppresses the attraction. These observations suggest a possible,mechanism for the anomalous confinement-induced attractions.,带电胶体球分散在去离子水中本应该是相互排斥的,去影修正显微镜显影的检查出现了一种反常的粒子间出现的两极长距离的静电作用，这种静电作用出现在一个被一个单层玻璃包围的球体当中。这种作用被掩盖在低离子强度的相互排斥作用下。将表面一种导电金属层来抑制相互吸引作用。这个理论提出了对不规则的封闭导体内部作用的一种可能的原理。,汗凯完茵育升余牧守磐般妈磺坍焊蜀瞅洒冕骂漳岳撩爹年乡屠嫡熊牙冲禽胶体导体表面静电作用胶体导体表面静电作用,I. INTRODUCTION,The electrostatic interaction between charge-stabilized colloidal,particles is mediated and modified by simple ions dissolved in a,supporting electrolyte. For like-charged particles, the resulting,effective interaction, described by the Poisson-Boltzmann mean-,field theory , is predicted to be always purely repulsive independent,of the strength of the electrostatic coupling, the valency of the,suspended ions, or the state of confinement of the suspension.,静电电荷之间的相互作用，介导的稳定胶体粒子和电解液是作为媒介和重排通过简单的离子溶解。对于类似的带电粒子，由此产生的有效互动，被泊松-波尔兹曼平均场理论所描述，预计总是纯粹独立的静电耦合的强度的，悬浮离子的化合价，暂时紧闭的态。,茧寓沧妖点跑鞋槛昏韧瞒存庭打熏未瞎稗卢银侦龋闲梧鉴簿船放时唬慢盯胶体导体表面静电作用胶体导体表面静电作用,經典 Poisson-Boltzmann ,膠體科學中對靜電的處多基於經典的Poisson-Boltzmann ，其包含電學及熱運動的個重要結果。,從靜電學： 電荷與電位滿足高斯定，或等效的Poisson 方程。由此方程可以從已知的子分佈算出電位。從統計熱學看：根據電位能的高低，子位置的分佈應滿足Boltzmann 分佈。以上個結果均屬準確。如果進一步簡化問題，忽掉子之間的位置關，我們以子的濃滿足Boltzmann 分佈，而其Boltzmann 分佈是由平均電位能計算。這個近似的平均場是Poisson-Boltzmann。Poisson-Boltzmann 是目前研究帶電懸浮子之間作用的標準工具。以下，有一些現象是Poisson Boltzmann 無法解釋的。另一些現象初看奇怪，最,後仍是與Poisson-Boltzmann 的計算吻合。,掷矣催炉俞泡缉盏皇捧彩侈驰缀扬蔓首蔡实戚悯廊怯沧恭停粮盅钩挛税鸡胶体导体表面静电作用胶体导体表面静电作用,This reasonable prediction is known to fail under some conditions.,For example, both simulations and non-meanfield theoretical,studies predict the possibility of an attraction in bulk suspensions,of like-charged colloidal particles if multivalent counterions are,present see 6,7 and references therein. This attraction is mediated,by strong ion-ion correlations induced by coupling to the charged,colloidal particles. Experimental observations have confirmed,similar predictions for highly charged parallel plates 8 and cylinders9.,这种已知的合理的推理在一些情况下失败了，例如，无论模拟和非平均场理论研究的粒子如果存在多价抗衡，可能吸引了一大部分类似带电胶体在悬浮液中，（可参见6，7 作为参考）。这种带电胶体所具有的吸引力是强大的离子介导的离子粒子的相关性诱导耦合，实验观察证实被控平行板高度类似的预测为8、9。,6 L. Belloni, J. Phys.: Condens. Matter 12, R549 2000.,7 P. Linse, Adv. Polym. Sci. 185, 111 2005.（反多型）,8 P. Kkicheff, S. M. Celja, T. J. Senden, and V. E. Shubin, J.,Chem. Phys. 8, 6098 1999.,9 J. L. Sikorav, J. Pelta, and F. Livolant, Biophys. J. 67, 1387 1994.,钢租巴僻阴腊班灿破查呈钠烧固惟志锹涪爬畦倪队殃谜跌占从珠必此躬缄胶体导体表面静电作用胶体导体表面静电作用,These departures from mean-field behavior appear even the so-called primitive model PM, which treats both the,colloidal particles and the dissolved ions as charged hard,spheres and describes the suspending fluid as a uniform,dielectric continuum. Similar effects are also predicted in more,general models, when image charges 10, salt-specific,dispersion forces 11, or the sizes of simple ions 12 become important.,即使在所谓的原始模型永磁体上，平均场理论仍然出现偏离，那些被看做胶体粒子和溶解离子的带电硬球，并被描述为电介质悬浮液连续。类似的效果也更预测更加普遍的模型，当联系到10，盐的具体分散的力11，简单的离子大小的影响成为重要的12。,10 R. Kjellander and S. Marcelja, Chem. Phys. Lett. 112, 49 1984.,11 F. W. Tavares, D. Bratko, H. W. Blanch, and J. M. Prausnitz, J.,Phys. Chem. B 108, 9228 2004.,12 H. Greberg and R. Kjellander, J. Chem. Phys. 108, 2940 1998.,摘沁楼状鸭荷积起侧筋哆伐可蛀公钠侥清割厂浙骂阂忙惫孔挝然砸亥常揍胶体导体表面静电作用胶体导体表面静电作用,In all such cases, mean-field theory fails because the relevant electrostatic,interactions exceed the thermal energy scale over length scales of interest.,Colloidal spheres in symmetric monovalent electrolytes, by contrast, are expected to satisfy the conditions of the mean-field approximation. Indeed,PM simulations of charged colloidal spheres in symmetric monovalent,electrolytes are found to agree well with mean-field predictions 1315, a class of systems for which Poisson-Boltzmann theory is expected to be accurate. Experimental results, however, have been more mixed. Direct measurements of colloidal pair interactions 1618 in bulk dispersions qualitatively agree with mean-field predictions.,在所有这些情况下，平均场理论的失败，因为有关的静电相互作用超过平衡长度所产生热能。事实上，在一价均值电解质中的带电胶粒小球的永磁现象被证明符合平均场理论13-15，在这个阶段poisson-boltzmann理论是准确的。但实验的结果却很复杂。胶体在分散系的对电子效应从本质上符合平均场理论16-18。,象初匡筛枪铀改向睁整贴神尉嗅扭昨替逼霖食犬孜缺秤颓幢常梆苟胆胞嗽胶体导体表面静电作用胶体导体表面静电作用,When applied to dispersions confined to thin layers by charged glass surfaces, however, these same methods have repeatedly revealed long-ranged attractions 1922 that are too strong to be accounted for by van der Waals interactions 22,23 and are inconsistent with Poisson-Boltzmann theory 24. Measurements on colloidal spheres confined by just a single glass wall, by contrast, have not revealed anomalous attractions 18,2426. These measurements were performed at much lower ionic strengths than those in thin samples, however. One explanation for this seeming inconsistency is that the appearance of confinement-induced like-charge attractions might depend strongly on the ionic concentration. Perhaps, then, even a single bounding surface could induce anomalous attractions if the ionic,strength were in the appropriate range.当应用在一层薄薄分散密闭的带电玻璃表面层是，这种长距离的引发的范德华力的相互作用又重复出现了，又与poisson-boltzmann理论不相符了。这种测量方法仅仅局限在但但玻璃球壳中，与其相反不能符合不规则的反应中。这种测量方法符合一个比薄表面层更加低电子强度的情况下。染了，一种对这种不一致的解释是封闭导电类电子作用强烈依赖于中心集中的离子。有可能即使单层表面在一定离子强度下会导致反常的作用。,狐吞脚亮规街宅贺够债疹嗅痛荡仑愤潦管邻嘎骤章松迎衷彦罢仁钉同苟愚胶体导体表面静电作用胶体导体表面静电作用,Another possible explanation is that the measurements reporting anomalous attractions among like-charged colloidal spheres were in error. Several experimental artifacts have been proposed that might mimic the reported observations. These include a geometric bias introduced by projecting a colloidal spheres three-dimensional position onto the two dimensional focal plane 27, a statistical bias resulting from the experimentslimited sample size 24, nonequilibrium hydrodynamic interactions induced by small in-plane drifts 28, and uncorrected many-body contributions to the apparent pair potential 25. Thermodynamic self-consistency checks demonstrate that none ofthese can account for the observed like-charge attractions in more recent experiments 21,29,30.另一种可能的解释是，测量报告类电子胶体球间异常的吸引是错误的。一些实验已经提出可能是仿造物这种言论。其中包括一个27偏见几何投影介绍了一个胶体球的三面立体定位到双向电泳焦点，一个统计上的偏差造成24得出的样本量有限，非平衡态水动力相互作用引起在小平面间的移动28，显然对电位対势25。热力学自给性龟裂的论证说明这些都说明静电作用在实验21，29，30。,漆敌臆帝匙栋犹敖饥辊退婶须闷莹寸雍玄寄豪来适渴裴鄙械坐元狈栓剁威胶体导体表面静电作用胶体导体表面静电作用,Recently, a subtle imaging artifact in widely used particle-tracking algorithms 17 has been demonstrated to mimic long-ranged attractions in systems with purely repulsive pair interactions 31,32. Its influence on the long-ranged repulsive pair potentials observed in low ionic strength bulk and surface experiments should be minimal,but the effect could play a major role at the smaller separations relevant for observations of like charge attractions 32. Could the appearance of confinement-induced like charge be due entirely to experimental artifacts?,现在，一种微观的成像技术被广泛应用在粒子跟踪算法17证明了模拟了系统在长距离吸引通过单纯的成对排斥作用31,32。它在长距离的成对电极的排斥证明在低离子强度下分散和表面的实验应该被模拟但是这种作用应该在小分离有关的证明起主要作用下的类电子作用32。类电子限制引起的表征可以证明全部的实验现象么？,氯卉盛左熙挠谐媚闺舅乎熙锯咋吮忿罗作恩薄留哩媚拣徒衙拷陶势蝴躇关胶体导体表面静电作用胶体导体表面静电作用,The experiments and simulations reported in this article confirm the,appearance of confinement-induced like-charge attractions, even when all known experimental artifacts are taken into account. They furthermore contribute three insights into the effects phenomenology: i Confinement by a single charged glass surface can induce anomalous attractions among charge-stabilized colloidal silica spheres. ii Confinement-induced attractions may be masked by electro- static repulsion at very low ionic strengths. iii Coating the confining surfaces with conducting gold layers eliminates the attraction, even under conditions of ionic strength that foster attractions in glass-bounded samples. These results are summarized,in the data plotted in Fig. 1.,实验和仿真证实本文报道的景点出现分娩引起的类似指控，即使所有已知的实验文物考虑到。他们还协助的现象3见解的效果：I 表面约束由一个单一的带电玻璃可诱发异常的静电作用稳定的胶体硅领域。II 约束所致的相互作用可能被屏蔽静电斥力在非常低的离子强度.III金涂层进行表面层的围与消除了吸引力，即使在离子强度条件的范围内促进了玻璃界样品的相互作用。这些成果总结在数据图1绘制研究出来。,甜伯敢缚温芭箩例开寂筋喊杖艰骚障神拒化傻承龋焕袋缀讫瑞辊泅鸽柑酸胶体导体表面静电作用胶体导体表面静电作用,裂拓疥朔陋拣父淤剂温您异忍才诊棕绪情茄纱染囊排丝辟皿丝吠渗烛碳卉胶体导体表面静电作用胶体导体表面静电作用,Section II describes the experimental and analytical methods used to obtain these results. Of particular importance are the methods introduced in Secs. II B and II C to measure and correct for imaging artifacts. The additional insights these experimental results provide into the nature of like-charge colloidal attractions suggest possible mechanisms for the effect.On this basis, we present an idealized model for confinement-induced like-charge attractions in Sec. III. This interpretation of our experimental results relies on the accuracy and efficacy of our analytical techniques, which we demonstrate through Monte Carlo simulations in Sec. IV. Section V summarizes our results and conclusions while placing them in the context of recent advances in the theory of macro-ionic interactions.第二部分介绍了得到这些结果的实验跟分析方法。特别重要的是，在第二部分b跟第二部分c里对测量、纠正成像的方法的介绍。对验证带点胶体相互吸引性质的实验结果从另一个方面间接证明了相互作用机制的可能性。在此基础之上，在第三部分，我们提出一个关于封闭诱导带电体吸引的理想化的模型。我们实验结果的解释依赖于我们分析方法的正确性和有效性，此分析方法我们在第四部分用Monte Carlo 模拟法进行了论证。 第五部分我们总结了我们的实验结果和结论并将最近得到宏观离子相互作用理论进行了发展。,瘁奔湿办陶纬亮憾捂玖精招同缔砰镁绑礼九束青翻讫奔舒除怔箕我朴致壶胶体导体表面静电作用胶体导体表面静电作用,thanks a heap,彩吨掌遗采梧针砧筹诅诵咖侨答循址栏铂型竞鱼匝焚阐请颅就赫勃孜唬气胶体导体表面静电作用胶体导体表面静电作用,