Electric-field-induced chain formation in dilute, non-aqueous suspensions of sterically stabilized, 1 µm poly(methyl methacrylate)(PMMA) latices are investigated. Optical microscopy and digital image analysis provide the chain-length distribution. We find that the particles carry a charge sufficient to inhibit field-induced aggregation. Equilibrium predictions of chain aggregation incorporating a screened Coulombic repulsion and field-induced dipole attraction agree well with experimental observations near the onset of aggregation; chain formation becomes diffusion limited above the threshold field strength.
{"title":"Electric-field-induced aggregation in dilute colloidal suspensions","authors":"Paul M. Adriani, A. Gast","doi":"10.1039/DC9909000017","DOIUrl":"https://doi.org/10.1039/DC9909000017","url":null,"abstract":"Electric-field-induced chain formation in dilute, non-aqueous suspensions of sterically stabilized, 1 µm poly(methyl methacrylate)(PMMA) latices are investigated. Optical microscopy and digital image analysis provide the chain-length distribution. We find that the particles carry a charge sufficient to inhibit field-induced aggregation. Equilibrium predictions of chain aggregation incorporating a screened Coulombic repulsion and field-induced dipole attraction agree well with experimental observations near the onset of aggregation; chain formation becomes diffusion limited above the threshold field strength.","PeriodicalId":12210,"journal":{"name":"Faraday Discussions of The Chemical Society","volume":"14 1","pages":"17-29"},"PeriodicalIF":0.0,"publicationDate":"1990-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81785365","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A comparative in situ time-resolved X-ray absorption study of the electrochemical inclusion of copper and iron species in poly(3-methyl-thiophene)(PMeT) is reported. For both treatments, incorporation of metallic ion and complexation with sulphur atoms of the polymer backbone lead to a significant increase of the ex situ macroscopic conductivity. However, the detailed mechanisms and kinetics of the various processes are specific to the metallic ion incorporated in the polymer.
{"title":"Electrochemical inclusion of copper and iron species in a conducting polymer observed in situ using time-resolved X-ray absorption spectroscopy","authors":"D. Guay, G. Tourillon, A. Fontaine","doi":"10.1039/DC9908900041","DOIUrl":"https://doi.org/10.1039/DC9908900041","url":null,"abstract":"A comparative in situ time-resolved X-ray absorption study of the electrochemical inclusion of copper and iron species in poly(3-methyl-thiophene)(PMeT) is reported. For both treatments, incorporation of metallic ion and complexation with sulphur atoms of the polymer backbone lead to a significant increase of the ex situ macroscopic conductivity. However, the detailed mechanisms and kinetics of the various processes are specific to the metallic ion incorporated in the polymer.","PeriodicalId":12210,"journal":{"name":"Faraday Discussions of The Chemical Society","volume":"21 1","pages":"41-50"},"PeriodicalIF":0.0,"publicationDate":"1990-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77713614","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The depth of the potential well for contacting particles determines the texture of a floc. This energy can be calculated from the interaction forces between the particles. In electrocratic colloids it depends on the counter-ion valency z, the (local) potential ϕδ near the contact point and the curvature of the surfaces in contact. However, it does not depend on the Debye length, 1/κ, which measures the range of the repulsive forces.At a critical value Zc for the parameter Z=zeϕδ the minimum disappears. For Z Zc flocs are unstable: they would repeptize or at least rearrange their texture.Because the rules of Schulze and Hardy and of Eilers and Korff apply simultaneously it can be derived that ϕδ is low (Z < Zc) and that Z has an equal value in sols when they coagulate at equal rates in electrolytes with different z. This theoretical observation has been verified experimentally. The double-layer potential, ϕδ, is indeed inversely proportional to z under such conditions. As a consequence, the parameter γ= tanh (zeϕδ/4kBT), which represents the influence of double-layer potentials in the DLVO theory, becomes a constant for conditions of equal rate. But, unlike the suggestion in the classical theory γ≠ 1, and its value is required to account for experimental observations.When sols coagulate at the same rate the depth of the potential well for aggregates increases with z. This effect is readily observed, since it is reflected in the texture of the flocs which are formed. Both Z(i.e. ϕδ) and z are variables in the coagulation conditions, and can be used to control the porosity of flocs, sediments and materials, which are prepared by sol–gel and related methods.
{"title":"Interacting particles in contact","authors":"G. Frens","doi":"10.1039/DC9909000143","DOIUrl":"https://doi.org/10.1039/DC9909000143","url":null,"abstract":"The depth of the potential well for contacting particles determines the texture of a floc. This energy can be calculated from the interaction forces between the particles. In electrocratic colloids it depends on the counter-ion valency z, the (local) potential ϕδ near the contact point and the curvature of the surfaces in contact. However, it does not depend on the Debye length, 1/κ, which measures the range of the repulsive forces.At a critical value Zc for the parameter Z=zeϕδ the minimum disappears. For Z Zc flocs are unstable: they would repeptize or at least rearrange their texture.Because the rules of Schulze and Hardy and of Eilers and Korff apply simultaneously it can be derived that ϕδ is low (Z < Zc) and that Z has an equal value in sols when they coagulate at equal rates in electrolytes with different z. This theoretical observation has been verified experimentally. The double-layer potential, ϕδ, is indeed inversely proportional to z under such conditions. As a consequence, the parameter γ= tanh (zeϕδ/4kBT), which represents the influence of double-layer potentials in the DLVO theory, becomes a constant for conditions of equal rate. But, unlike the suggestion in the classical theory γ≠ 1, and its value is required to account for experimental observations.When sols coagulate at the same rate the depth of the potential well for aggregates increases with z. This effect is readily observed, since it is reflected in the texture of the flocs which are formed. Both Z(i.e. ϕδ) and z are variables in the coagulation conditions, and can be used to control the porosity of flocs, sediments and materials, which are prepared by sol–gel and related methods.","PeriodicalId":12210,"journal":{"name":"Faraday Discussions of The Chemical Society","volume":"54 1","pages":"143-151"},"PeriodicalIF":0.0,"publicationDate":"1990-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80411310","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
E. Dooryhee, G. Greaves, A. T. Steel, R. P. Townsend, S. Carr, John Meurig Thomas, C. Catlow
We have characterized at high temperature a model uniform heterogeneous catalyst for the oligomerization of hydrocarbons (a nickel-exchanged zeolite of initial composition Na59Al59Si133O384·xH2O treated with an aqueous solution of NiCl2 so as to yield a homogeneous distribution of Ni, with Si/Ni = 7) by recording the extended X-ray absorption fine structure (EXAFS) above the Ni edge and also its high-resolution diffraction pattern (at λ= 1.5486 A). We have obtained unique insights into the microenvironment of the Ni2+ ions in the as-prepared and the dehydrated as well as the reduced state of the catalyst; in particular, values of atomic coordinates, site-occupancy and bond lengths, have been obtained. High-resolution X-ray diffraction, using a specially constructed environmental cell, has enabled the precise location of sorbed Xe atoms in a sodium-exchanged zeolite X adsorbent (1.5 atoms of Xe per unit cell) under a pressure of 1.75 bar at room temperature to be determined from a Rietveld refinement of the powder diffraction pattern. Direct proof of the role of the strongly polarizing Na+ ion located at the SΠ site in firmly binding the Xe to the inner wall of the supercage is obtained.X-ray absorption near-edge structures (XANES) as well as parallel EXAFS studies above the Al, Si and Ga edges on a variety of other zeolites are also reported. Combined (Ga edge) XANES and EXAFS studies show that gallosilicate networks akin to those present in crystalline (gallo) zeolite X and Y are already formed in the precursor gel and are also present in the aqueous solution in contact with the colloidal-amorphous material, which together constitute the gel. We also report one of the first applications of Al EXAFS for the semi-quantitative study of the dealumination of faujasitic zeolites.
{"title":"Structural studies of high-area zeolitic adsorbents and catalysts by a combination of high-resolution X-ray powder diffraction and X-ray absorption spectroscopy","authors":"E. Dooryhee, G. Greaves, A. T. Steel, R. P. Townsend, S. Carr, John Meurig Thomas, C. Catlow","doi":"10.1039/DC9908900119","DOIUrl":"https://doi.org/10.1039/DC9908900119","url":null,"abstract":"We have characterized at high temperature a model uniform heterogeneous catalyst for the oligomerization of hydrocarbons (a nickel-exchanged zeolite of initial composition Na59Al59Si133O384·xH2O treated with an aqueous solution of NiCl2 so as to yield a homogeneous distribution of Ni, with Si/Ni = 7) by recording the extended X-ray absorption fine structure (EXAFS) above the Ni edge and also its high-resolution diffraction pattern (at λ= 1.5486 A). We have obtained unique insights into the microenvironment of the Ni2+ ions in the as-prepared and the dehydrated as well as the reduced state of the catalyst; in particular, values of atomic coordinates, site-occupancy and bond lengths, have been obtained. High-resolution X-ray diffraction, using a specially constructed environmental cell, has enabled the precise location of sorbed Xe atoms in a sodium-exchanged zeolite X adsorbent (1.5 atoms of Xe per unit cell) under a pressure of 1.75 bar at room temperature to be determined from a Rietveld refinement of the powder diffraction pattern. Direct proof of the role of the strongly polarizing Na+ ion located at the SΠ site in firmly binding the Xe to the inner wall of the supercage is obtained.X-ray absorption near-edge structures (XANES) as well as parallel EXAFS studies above the Al, Si and Ga edges on a variety of other zeolites are also reported. Combined (Ga edge) XANES and EXAFS studies show that gallosilicate networks akin to those present in crystalline (gallo) zeolite X and Y are already formed in the precursor gel and are also present in the aqueous solution in contact with the colloidal-amorphous material, which together constitute the gel. We also report one of the first applications of Al EXAFS for the semi-quantitative study of the dealumination of faujasitic zeolites.","PeriodicalId":12210,"journal":{"name":"Faraday Discussions of The Chemical Society","volume":"246 1","pages":"119-136"},"PeriodicalIF":0.0,"publicationDate":"1990-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76945566","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper briefly reviews information recently obtained from grazing incidence X-ray diffraction studies of the structures of the several phases in the high-surface-density region of an amphiphile monolayer on water. We also present a new theory, based on a density functional formalism, for the transition between untilted (hexagonal) and tilted (distorted hexagonal) phases in these monolayers. We find that in the region from 0 to ca. 0.5 rad tilt angle the tilted states are thermodynamically more stable (ca. 0.2–2.0 kBT per segment lower in free energy) than the untilted state, so that the monolayer, when expanded, always adopts the value of tilt angle determined by the area per molecule. Eventually, for large tilt, say e.g. > 0.6 rad, the chemical potential of the monolayer increases as the tilt increases. There is, then, a minimum of the free energy versus tilt angle for which the constraint derived from the area per molecule is effectively relieved. We find that an incompressible monolayer has a small change in average density and a large change in area per molecule across the transition. Conversely, a monolayer with large compressibility has a large density change and a small change in area per molecule across the transition. Our analysis correctly reproduces the principal features of the observed phase transitions. We speculate on the nature of ‘island phases’ and the relation of these to the close-packed phases of the monolayer.
{"title":"Langmuir monolayers: structures and phase transitions","authors":"Z. Cai, S. Rice","doi":"10.1039/DC9908900211","DOIUrl":"https://doi.org/10.1039/DC9908900211","url":null,"abstract":"This paper briefly reviews information recently obtained from grazing incidence X-ray diffraction studies of the structures of the several phases in the high-surface-density region of an amphiphile monolayer on water. We also present a new theory, based on a density functional formalism, for the transition between untilted (hexagonal) and tilted (distorted hexagonal) phases in these monolayers. We find that in the region from 0 to ca. 0.5 rad tilt angle the tilted states are thermodynamically more stable (ca. 0.2–2.0 kBT per segment lower in free energy) than the untilted state, so that the monolayer, when expanded, always adopts the value of tilt angle determined by the area per molecule. Eventually, for large tilt, say e.g. > 0.6 rad, the chemical potential of the monolayer increases as the tilt increases. There is, then, a minimum of the free energy versus tilt angle for which the constraint derived from the area per molecule is effectively relieved. We find that an incompressible monolayer has a small change in average density and a large change in area per molecule across the transition. Conversely, a monolayer with large compressibility has a large density change and a small change in area per molecule across the transition. Our analysis correctly reproduces the principal features of the observed phase transitions. We speculate on the nature of ‘island phases’ and the relation of these to the close-packed phases of the monolayer.","PeriodicalId":12210,"journal":{"name":"Faraday Discussions of The Chemical Society","volume":"64 1","pages":"211-229"},"PeriodicalIF":0.0,"publicationDate":"1990-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79512750","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The theory of X-ray scattering from surfaces is reviewed. A simple kinematical derivation is given of the surface truncation rods occurring near Bragg reflections and of the specular reflectivity. The dynamical theory is then discussed and it is shown that the 1/θ2 tails in the theory arise from kinematic surface scattering, and, furthermore, also have the same origin as the specular reflection for θ > θc. The effect of surface roughness is then described. The techniques are then used to analyse X-ray measurements of the photodissolution of silver into As30S70. X-ray measurements are performed of the powder scattering from the thin silver layer, of the reflectivity and of the off-specular scattering at small angles. By combining all of these a detailed picture of the dissolution process is constructed. The process is then used to construct a diffraction grating and this is studied by X-ray reflectivity to study in detail the lithographic process. The extent of the blurring of the steps is determined and a model of the strucure constructed.
{"title":"X-Ray Scattering from Surfaces and Interfaces","authors":"R. Cowley, C. Lucas","doi":"10.1039/DC9908900181","DOIUrl":"https://doi.org/10.1039/DC9908900181","url":null,"abstract":"The theory of X-ray scattering from surfaces is reviewed. A simple kinematical derivation is given of the surface truncation rods occurring near Bragg reflections and of the specular reflectivity. The dynamical theory is then discussed and it is shown that the 1/θ2 tails in the theory arise from kinematic surface scattering, and, furthermore, also have the same origin as the specular reflection for θ > θc. The effect of surface roughness is then described. The techniques are then used to analyse X-ray measurements of the photodissolution of silver into As30S70. X-ray measurements are performed of the powder scattering from the thin silver layer, of the reflectivity and of the off-specular scattering at small angles. By combining all of these a detailed picture of the dissolution process is constructed. The process is then used to construct a diffraction grating and this is studied by X-ray reflectivity to study in detail the lithographic process. The extent of the blurring of the steps is determined and a model of the strucure constructed.","PeriodicalId":12210,"journal":{"name":"Faraday Discussions of The Chemical Society","volume":"68 1","pages":"181-190"},"PeriodicalIF":0.0,"publicationDate":"1990-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82665385","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Kilcoyne, D. P. Woodruff, A. W. Robinson, T. Lindner, J. Somers, D. Ricken, A. Bradshaw
Scanned energy mode adsorbate 1s photoelectron diffraction measurements have been taken from half-monolayer structures of O on Ni(100) and on Cu(110), and from C and N on Ni(100). The sensitivity of these data to the various structural parameters of these surface phases is investigated. In particular, the fact that 180° scattering contributions typically dominate the spectra in this form of the photoelectron diffraction experiment leads to a strong sensitivity to adsorbate–second layer substrate spacings. Even in the case in which the adsorbate and top substrate layers are nearly coplanar, however, some sensitivity to top layer geometry is retained, except in the case of the Cu(110) surface for which the lower rotational symmetry, combined with the plane polarisation of the incident radiation, leads to insensitivity to certain sites.
{"title":"Photoelectron diffraction study of O, N and C adsorption structures on Ni(100) and Cu(110)","authors":"A. Kilcoyne, D. P. Woodruff, A. W. Robinson, T. Lindner, J. Somers, D. Ricken, A. Bradshaw","doi":"10.1039/DC9908900311","DOIUrl":"https://doi.org/10.1039/DC9908900311","url":null,"abstract":"Scanned energy mode adsorbate 1s photoelectron diffraction measurements have been taken from half-monolayer structures of O on Ni(100) and on Cu(110), and from C and N on Ni(100). The sensitivity of these data to the various structural parameters of these surface phases is investigated. In particular, the fact that 180° scattering contributions typically dominate the spectra in this form of the photoelectron diffraction experiment leads to a strong sensitivity to adsorbate–second layer substrate spacings. Even in the case in which the adsorbate and top substrate layers are nearly coplanar, however, some sensitivity to top layer geometry is retained, except in the case of the Cu(110) surface for which the lower rotational symmetry, combined with the plane polarisation of the incident radiation, leads to insensitivity to certain sites.","PeriodicalId":12210,"journal":{"name":"Faraday Discussions of The Chemical Society","volume":"1 1","pages":"311-321"},"PeriodicalIF":0.0,"publicationDate":"1990-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81809508","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Suspensions of charged rod-like particles are investigated theoretically in a concentration regime where the mean distance between rods is comparable to their length, L. The structure of these systems is studied by Monte Carlo simulations and a perturbation theoretical scheme. Results for the pair distribution function g(12) are obtained, which show the onset of angular correlations at the cross-over concentration c*=L–3. Above c* there is a tendency for local alignments of neighbouring rods, although the systems remain globally isotropic up to c= 4c*, which is the highest concentration investigated. As a consequence, the peak position kmax of the structure factor S(k) scales as kmax∼c1/2 for c > c* in contrast to the c1/3 behaviour for c < c*, where the rods behave as spherical particles. The time-correlation function of quasielastic scattering experiments is derived from a dynamical mean field theory. From it the collective diffusion coefficient and the first cumulant are obtained. The influence of the interaction between rods and of the coupling of translational and rotational diffusion are discussed.
{"title":"Structure and dynamics of suspensions of charged rod-like particles","authors":"B. Weyerich, B. D’Aguanno, E. Canessa, R. Klein","doi":"10.1039/DC9909000245","DOIUrl":"https://doi.org/10.1039/DC9909000245","url":null,"abstract":"Suspensions of charged rod-like particles are investigated theoretically in a concentration regime where the mean distance between rods is comparable to their length, L. The structure of these systems is studied by Monte Carlo simulations and a perturbation theoretical scheme. Results for the pair distribution function g(12) are obtained, which show the onset of angular correlations at the cross-over concentration c*=L–3. Above c* there is a tendency for local alignments of neighbouring rods, although the systems remain globally isotropic up to c= 4c*, which is the highest concentration investigated. As a consequence, the peak position kmax of the structure factor S(k) scales as kmax∼c1/2 for c > c* in contrast to the c1/3 behaviour for c < c*, where the rods behave as spherical particles. The time-correlation function of quasielastic scattering experiments is derived from a dynamical mean field theory. From it the collective diffusion coefficient and the first cumulant are obtained. The influence of the interaction between rods and of the coupling of translational and rotational diffusion are discussed.","PeriodicalId":12210,"journal":{"name":"Faraday Discussions of The Chemical Society","volume":"1 1","pages":"245-259"},"PeriodicalIF":0.0,"publicationDate":"1990-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83617982","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
R. V. Silfhout, J. V. D. Veen, C. Norris, J. E. MacDonald
In an X-ray diffraction study of the c(2 × 8) reconstructed Ge(111) surface we have measured intensity profiles along integer-order rods of Bragg scattering perpendicular to the surface plane. The diffracted intensity profiles are explained in terms of a simple adatom model for the reconstruction. The adatoms are found to occupy T4 sites on a distorted bulk-like substrate. We rule out any model for c(2 × 8) reconstruction that is based on stacking faults in the substrate. For the adatom model we give best-fit values for the positions of the atoms at the surface and compare them with those obtained from total-energy and keating-energy minimisation calculations.
{"title":"Structure of the Ge(111)-c(2 × 8) surface as determined from scattered X-ray intensities along crystal truncation rods","authors":"R. V. Silfhout, J. V. D. Veen, C. Norris, J. E. MacDonald","doi":"10.1039/DC9908900169","DOIUrl":"https://doi.org/10.1039/DC9908900169","url":null,"abstract":"In an X-ray diffraction study of the c(2 × 8) reconstructed Ge(111) surface we have measured intensity profiles along integer-order rods of Bragg scattering perpendicular to the surface plane. The diffracted intensity profiles are explained in terms of a simple adatom model for the reconstruction. The adatoms are found to occupy T4 sites on a distorted bulk-like substrate. We rule out any model for c(2 × 8) reconstruction that is based on stacking faults in the substrate. For the adatom model we give best-fit values for the positions of the atoms at the surface and compare them with those obtained from total-energy and keating-energy minimisation calculations.","PeriodicalId":12210,"journal":{"name":"Faraday Discussions of The Chemical Society","volume":"18 1","pages":"169-180"},"PeriodicalIF":0.0,"publicationDate":"1990-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91062601","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A theoretical model has been developed that describes the diffuse double layer near a flat plate having an inhomogeneous surface potential. It is shown that the charge is screened not only by the traditional Debye–Huckel screening perpendicular to the wall, but also in the lateral direction of the double layer. This contribution is dependent on the periodicity of the surface potential.The interaction potential has been computed between two plates for a general surface-potential distribution under the assumption that the surface-potential distribution on each plate is constant when they approach. The results show that the interaction potential depends to a large extent on the periodicity of the surface potential.
{"title":"Interaction potential of a dispersion of colloidal particles with a non-homogeneous surface potential","authors":"A. J. Kuin","doi":"10.1039/DC9909000235","DOIUrl":"https://doi.org/10.1039/DC9909000235","url":null,"abstract":"A theoretical model has been developed that describes the diffuse double layer near a flat plate having an inhomogeneous surface potential. It is shown that the charge is screened not only by the traditional Debye–Huckel screening perpendicular to the wall, but also in the lateral direction of the double layer. This contribution is dependent on the periodicity of the surface potential.The interaction potential has been computed between two plates for a general surface-potential distribution under the assumption that the surface-potential distribution on each plate is constant when they approach. The results show that the interaction potential depends to a large extent on the periodicity of the surface potential.","PeriodicalId":12210,"journal":{"name":"Faraday Discussions of The Chemical Society","volume":"43 1","pages":"235-244"},"PeriodicalIF":0.0,"publicationDate":"1990-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79323290","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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