Observation of Molecular Layering in Thin Liquid Films Using X-Ray Reflectivity

Yu, Chung-Jong; Richter, A. G.; Datta, Alokmay; Durbin, Mary K; Dutta, Pulak

doi:10.1103/physrevlett.82.2326

Cited by 228 publications

(146 citation statements)

References 22 publications

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“…This is consistent with some researchers [54][55][56][57] which considered the thickness of nanolayer between 1 and 3nm. However, previous research on the solid-liquid interface [51][52][53] showed that the nanolayer consist of different layer at the interface of the solid-liquid which can conclude that the property of nanolayer should be started from void to the base fluid. In this way the average thickness of the nanolayer of the nanofluids must be more than the tv.…”

Section: Model Development Results and Discussionmentioning

confidence: 99%

“…They concluded that the ordering of an interfacial layer in solidliquid interface is independent of liquid film thickness. Yu et al [51] studied interfacial properties of thin liquid film of TEHOS (tetrakis(2-ethylhexoxy)silane) on silicon (111) substrate by X-ray reflectivity. They showed that three electron density oscillations near the interface with a period of about 1nm, which is consistent with molecular density.…”

Section: Solid-liquid Interfacial Layermentioning

confidence: 99%

See 1 more Smart Citation

A new model for density of nanofluids including nanolayer

Sharifpur

Yousefi

Meyer

2016

International Communications in Heat and Mass Transfer

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Nanofluids which are suspension of nanoparticles in conventional heat transfer fluids attracted researchers while they show higher thermal conductivity and specific heat capacity. The important parameters have influence on thermal-fluid properties of nanofluids include the volume fraction of the nanoparticles, temperature, density of fluid base and nanoparticles, nanoparticles size, nanolayer, thermal conductivity of base fluid and particles, and pH. Nanolayer which is an approved interfacial layer between particles and base fluid involved in some of modelling for effective thermal conductivity and effective viscosity of nanofluids. Therefore, this layer must effect on other properties of nanofluids such as density. In this study investigation into the density of nanofluids has done experimentally.The nanofluids were investigated for density measurements consist of SiO2-Water, MgOGlycerol, CuO-Glycerol and SiOx-Ethylene Glycol /Water for range of 1 to 6% volume fraction as well as temperature range of 10 to 40 o C. The results show that mixture model for density of nanofluids (density of nanofluid = density of base fluid multiply by volume fraction of base fluid + density of nanoparticles multiply by volume fraction of nanoparticles) which is generally cited in literature has higher value than experimental data.For higher volume fraction of nanoparticles, the gap between the experimental results and the mixture model gets more. This is due to the nanolayer which also shows nanolayer density can be between void and the base fluid density. Therefore, based on the experimental data a new model for density of nanofluids developed which includes nanolayer. It was also found that the amount of the void in the nanolayer is more sensitive to nanoparticle size and not to base fluids or nanoparticles material.

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Section: Model Development Results and Discussionmentioning

confidence: 99%

Section: Solid-liquid Interfacial Layermentioning

confidence: 99%

A new model for density of nanofluids including nanolayer

Sharifpur

Yousefi

Meyer

2016

International Communications in Heat and Mass Transfer

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show abstract

“…1 In liquid films close to a flat solid surface, molecular layering is observed, [2][3][4] which is enhanced by confinement between two solid surfaces. New tools to study confined liquids include surface force apparatus (SFA), 2,5,6 atomic force microscopy (AFM), 7,8 and spectroscopic techniques 9 such as fluorescence correlation spectroscopy (FCS).…”

Section: Introductionmentioning

confidence: 99%

Solid or Liquid? Solidification of a Nanoconfined Liquid under Nonequilibrium Conditions

et al. 2006

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There has been a long-standing debate about the physical state and possible phase transformations of confined liquids. In this report, we show that a model-confined liquid can behave both as a Newtonian liquid with very little change in its dynamics and as a pseudosolid, depending solely on the rate of approach of the confining surfaces. Thus, the confined liquid does not exhibit any confinement-induced solidification in thermodynamic equilibrium. Instead, solidification is induced kinetically when the two confining surfaces are approached with a minimum critical rate. This critical rate is surprisingly slow (on the order of 6 Å/s), explaining the frequent observation of confinementinduced solidification.

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“…X-ray and neutron reflectivity have been extensively used to determine the density profiles at the free surfaces of many liquids [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25] including water, 22,25 and also at liquid-solid [26][27][28] and liquidliquid [29][30] interfaces. These probes are sensitive to electron density and scattering length density respectively, and for a known material these are both measures of the local mass density.…”

Section: Introductionmentioning

confidence: 99%

What x rays can tell us about the interfacial profile of water near hydrophobic surfaces

et al. 2013

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The free surface of water, and the interface between water and a hydrophobic surface, both have positive interface energies. The water density near a free surface drops below the bulk density, and thus it is expected that water near a hydrophobic surface will also show a density depletion.However, efforts by multiple groups to detect and characterize the predicted 'gap' at waterhydrophobic interfaces have produced contradictory results. We have studied the interface between water and fluoroalkylsilane self-assembled monolayers using specular X-ray reflectivity, and analyzed the parameter-space landscapes of the merit functions being minimized by data fitting. This analysis yields a better understanding of confidence intervals than the customary process of reporting a unique 'best' fit. We conclude that there are unambiguous gaps at water-hydrophobic interfaces when the hydrophobic monolayer is more densely packed.

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Observation of Molecular Layering in Thin Liquid Films Using X-Ray Reflectivity

Cited by 228 publications

References 22 publications

A new model for density of nanofluids including nanolayer

A new model for density of nanofluids including nanolayer

Solid or Liquid? Solidification of a Nanoconfined Liquid under Nonequilibrium Conditions

What x rays can tell us about the interfacial profile of water near hydrophobic surfaces

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