Finlayson Samuel D, Bartlett Paul
School of Chemistry, University of Bristol, Bristol BS8 1TS, United Kingdom.
J Chem Phys. 2016 Jul 21;145(3):034905. doi: 10.1063/1.4959122.
It is general wisdom that the pair potential of charged colloids in a liquid may be closely approximated by a Yukawa interaction, as predicted by the classical Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. We experimentally determine the effective forces in a binary mixture of like-charged particles, of species 1 and 2, with blinking optical tweezers. The measured forces are consistent with a Yukawa pair potential but the (12) cross-interaction is not equal to the geometric mean of the (11) and (22) like-interactions, as expected from DLVO. The deviation is a function of the electrostatic screening length and the size ratio, with the cross-interaction measured being consistently weaker than DLVO predictions. The corresponding non-additivity parameter is negative and grows in magnitude with increased size asymmetry.
一般认为，液体中带电胶体的对势可以通过经典的德亚金-朗道-韦弗-奥弗贝克（DLVO）理论所预测的 Yukawa 相互作用来紧密近似。我们使用闪烁光镊通过实验确定了 1 号和 2 号同种带电粒子二元混合物中的有效力。测量得到的力与 Yukawa 对势一致，但如 DLVO 所预期的那样，（12）交叉相互作用并不等于（11）和（22）同类相互作用的几何平均值。这种偏差是静电屏蔽长度和尺寸比的函数，所测量的交叉相互作用始终比 DLVO 预测的要弱。相应的非加和性参数为负，且其大小随尺寸不对称性的增加而增大。
