{"title":"Laser electrophoresis in surface electric double layer","authors":"S. Semenov","doi":"10.1039/A807555G","DOIUrl":null,"url":null,"abstract":"The dynamic scattering of laser light by dissolved charged macromolecules or suspended colloid particles in the surface potential well near the solid/liquid boundary is examined theoretically. This surface potential well is a combination of the long-range attraction potential of the electric double layer (EDL) and the short-range repulsion van der Waals potential. The frequency spectrum of the scattered light recorded in the heterodyne regime should contain peaks with the Doppler frequency shifts corresponding to the velocities of particle electrophoresis in the EDL. The wave reflected from the boundary surface may be used as the reference wave necessary in the heterodyne regime, and the intensity of the scattered wave collinear with the reflected wave should be recorded. Since field strengths in the EDL are about 105 V cm–1 such a method should have extremely high resolution. The case of the equilibrium reversible ‘partition’ of particles between the liquid film, where no force is present, and the surface layer is examined. In this case, the ‘partition coefficient’ defining the ratio of the bulk and surface fractions of particles may be about one, if the liquid film is thin enough (≈10–3 cm). Also, in this case, the integral frequency spectrum should contain the bulk part corresponding to the particle diffusion and the surface part with the Doppler peaks, where electrophoresis of particles should be seen.","PeriodicalId":7814,"journal":{"name":"Analytical Communications","volume":"55 1","pages":"369-372"},"PeriodicalIF":0.0000,"publicationDate":"1998-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"1","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Analytical Communications","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.1039/A807555G","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 1
Abstract
The dynamic scattering of laser light by dissolved charged macromolecules or suspended colloid particles in the surface potential well near the solid/liquid boundary is examined theoretically. This surface potential well is a combination of the long-range attraction potential of the electric double layer (EDL) and the short-range repulsion van der Waals potential. The frequency spectrum of the scattered light recorded in the heterodyne regime should contain peaks with the Doppler frequency shifts corresponding to the velocities of particle electrophoresis in the EDL. The wave reflected from the boundary surface may be used as the reference wave necessary in the heterodyne regime, and the intensity of the scattered wave collinear with the reflected wave should be recorded. Since field strengths in the EDL are about 105 V cm–1 such a method should have extremely high resolution. The case of the equilibrium reversible ‘partition’ of particles between the liquid film, where no force is present, and the surface layer is examined. In this case, the ‘partition coefficient’ defining the ratio of the bulk and surface fractions of particles may be about one, if the liquid film is thin enough (≈10–3 cm). Also, in this case, the integral frequency spectrum should contain the bulk part corresponding to the particle diffusion and the surface part with the Doppler peaks, where electrophoresis of particles should be seen.
从理论上研究了固体/液体边界附近表面势阱中溶解的带电大分子或悬浮胶体粒子对激光的动态散射。该表面电势井是双电层(EDL)的远程吸引电势和短程排斥范德华电势的结合。在外差状态下记录的散射光的频谱应该包含与EDL中颗粒电泳速度相对应的多普勒频移的峰。从边界面反射的波可以作为外差区所需的参考波,并记录与反射波共线的散射波强度。由于EDL中的场强约为105 V cm-1,因此这种方法应该具有极高的分辨率。在不存在力的情况下,粒子在液体膜和表层之间的平衡可逆“分配”的情况被检查。在这种情况下,如果液膜足够薄(≈10-3 cm),则定义颗粒体积分数和表面分数之比的“分配系数”可能约为1。同时,在这种情况下,积分频谱应该包含与颗粒扩散相对应的本体部分和具有多普勒峰的表面部分,其中应该可以看到颗粒的电泳。