X-ray study of the electric double layer at the n-hexane/nanocolloidal silica interface

Tikhonov, A. M.

doi:10.1063/1.2189848

Cited by 27 publications

(44 citation statements)

References 22 publications

(29 reference statements)

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“…The electron density profiles reconstructed with the model-independent approach are in agreement with the concept of the structure of the electric double layer on the surface of the hydrosol [17,18]. The gradient of the surface potential on it appears owing to the difference between the potentials of electric image forces for Na + cations and silica nanoparticles with a large negative charge (∼ 10 3 electrons) (macroions).…”

supporting

confidence: 60%

“…Figure 5 shows the reconstructed profiles ρ(z) in the surface of the layer of the sol of 7-nm particles divided by the electron density in water under normal conditions ρ(z) w = 0.333 e − /Å 3 . They qualitatively correspond to the model of electric double layer proposed in [17,18]. The thickness of the densest layer (loose nanoparticle monolayer) with a maximum at a depth of ∼ 150Å was ≈ 100Å and approximately corresponds to the diameter of SiO 2 nanoparticles in the sol.…”

mentioning

confidence: 98%

“…is the temperature, N A ≈ 6.02 · 10 23 mol −1 is the Avogadro number, e ≈ 1.6 · 10 −19 C is the elementary charge, and c − ≈ 10 −4 mol/L is the concentration of free OH − ions in the sol at [17,18]. Because of a small difference in pH, the parameter Λ D for the solution of 12-nm silica particles is larger than that for the solution of 7-nm particles by ∼ 40%.…”

mentioning

confidence: 99%

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Kinetics of the formation of a phospholipid multilayer on a silica sol surface

Tikhonov¹,

Асадчиков²,

Volkov³

et al. 2016

Jetp Lett.

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The ordering of a multilayer consisting of DSPC bilayers on a silica sol substrate is studied within the model-independent approach to the reconstruction of profiles of the electron density from X-ray reflectometry data. It is found that the electroporation of bilayers in the field of anion silica nanoparticles significantly accelerates the process of their saturation with Na + and H2O, which explains both a relatively small time of formation of the structure of the multilayer of (1 − 7) × 10 5 s and 13% excess of the electron density in it.

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supporting

confidence: 60%

mentioning

confidence: 98%

mentioning

confidence: 99%

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Kinetics of the formation of a phospholipid multilayer on a silica sol surface

Tikhonov¹,

Асадчиков²,

Volkov³

et al. 2016

Jetp Lett.

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“…The technique of x-ray reflectivity and its application to the study of liquid/liquid interfaces has been described previously in detail [8,[17][18][19]. We have used this technique to study molecular ordering and phase transitions in surfactant monolayers at oil/water interfaces [7-9, 13, 18, 20], the structure of neat oil/water interfaces [21][22][23][24], the adsorption of sodium ions at the oil/silica hydrosol interface [25], and the ordering of ions at the interface between two electrolyte solutions [26,27].…”

Section: X-ray Reflectivitymentioning

confidence: 99%

Vaporization and layering of alkanols at the oil/water interface

Tikhonov¹,

Schlossman²

2007

J. Phys.: Condens. Matter

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This study of adsorption of normal alkanols at the oil/water interface with x-ray reflectivity and tensiometry demonstrates that the liquid to gas monolayer phase transition at the hexane/water interface is thermodynamically favorable only for long-chain alkanols. As the alkanol chain length is decreased, the change in excess interfacial entropy per area ΔS a σ decreases to zero. Systems with small values of ΔS a σ form multi-molecular layers at the interface instead of the monolayer formed by systems with much larger ΔS a σ . Substitution of n-hexane by n-hexadecane significantly alters the interfacial structure for a given alkanol surfactant, but this substitution does not change fundamentally the phase transition behavior of the monolayers. These data show that the critical alkanol carbon number, at which the change in excess interfacial entropy per area decreases to zero, is approximately six carbons larger than the number of carbons in the alkane solvent molecules.2

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“…14,15 Thus, the distance between a SiOH site and an adsorbed cation is estimated to be 660 pm. The effective dielectric constant for water varies with electric field strength, Figure 2.…”

Section: ¹2mentioning

confidence: 99%

On the Relation between the Interfacial Charge of a Discharging Nozzle and Electrification of a Liquid Microjet

Kurahashi

Suzuki

2018

Chem. Lett.

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A liquid microjet discharged from a fused silica capillary is electrified, and the polarity of this electrification is opposite to that of the net charge at the solidliquid interface of the capillary nozzle. Keywords: Liquid microjet | Fused silica | Capillary nozzleLiquid microjets, cylindrical streams of liquid with a diameter of tens of micrometers, are now widely employed in photoelectron spectroscopy of liquids 1 and gas-surface scattering experiments.2 The small surface area of the microjet minimizes evaporation of solvent molecules and facilitates introduction of volatile liquids into high-vacuum chambers. However, a liquid microjet is electrically charged, because the liquid flow shears off an electric double layer at the inner wall of a capillary nozzle to create unequal number densities of cations and anions in the mobile part of the flow (flow electrification). 3,4 In a previous study, 5 we showed that the electric potential of a liquid microjet of NaX solution (X = Cl, Br, and I) varies with the electrolyte concentration. A notable common feature of the variation was that the polarity of the potential reverses at around a concentration of 30 mM (Figure 1), suggesting that Na + plays a key role in determining the polarity. In the present work, we discuss the relation between the electric charge at the inner wall of a capillary and the microjet.The electric potential (º d ) in the diffuse region of an electric double layer is described by the PoissonBoltzmann equation as follows,where e is the elementary charge, ¾ 0 and ¾ r are respectively the permittivity of vacuum and the relative permittivity of a solution, Z « and N « are respectively the charge and number density of positive/negative ions, k B is the Boltzmann constant, and T is the temperature. Equation 1 cannot be solved analytically. However, if the electric potential is sufficiently small such that the following condition holds, i.e.,an approximate solution can be expressed aswhere l is the distance from the inner wall of the capillary, º OHP is the electric potential at the outer Helmholtz plane (OHP), and l OHP is the position of the OHP. ¬ is the inverse of the Debye length, defined aswhere c is the concentration of the solution. º OHP is related to the interfacial charge º 0 bywhere · surf is the original charge density of the solid surface, · ad is the charge density of the adsorbed ions, and l IHP is the position of the inner Helmholtz plane (IHP). The relative permittivity is assumed to be the same in all regions of the solution. Then, the continuity conditions for the electric field and the potential at the OHP yieldIf eq 2 holds, the charge density in the diffuse layer is given bySince Z þ ¼ 1 and Z À ¼ À1 for NaX, eq 7 simplifies to μðlÞ % À2ceº OHP e À¬ðlÀlOHPÞ ð8ÞThis equation shows that the excess charge in a diffuse layer is opposite in sign to both º OHP and · surf þ · ad . Although eq 3 is valid only for small º d , the opposite signs of μ and · surf þ · ad are expected to be general. In this study, we examine the relation bet...

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X-ray study of the electric double layer at the n-hexane/nanocolloidal silica interface

Cited by 27 publications

References 22 publications

Kinetics of the formation of a phospholipid multilayer on a silica sol surface

Kinetics of the formation of a phospholipid multilayer on a silica sol surface

Vaporization and layering of alkanols at the oil/water interface

On the Relation between the Interfacial Charge of a Discharging Nozzle and Electrification of a Liquid Microjet

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