Quenching of capillary waves in composite wetting films from a binary vapor: An x-ray reflectivity study

Heilmann, Ralf K.; Fukuto, Masafumi; Pershan, Peter S.

doi:10.1103/physrevb.63.205405

Cited by 27 publications

(46 citation statements)

References 60 publications

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“…This thickness dependent surface roughness of the film can be explained by the van der Waals interaction between the liquid water substrate and the propane layer which affects the capillary wave induced surface roughness of the liquid layer [18,23]. The thickness dependent capillary wave roughness of the adsorbed layer can be calculated using a theory described in [31] which is based on a Taylor expansion of the interfacial potential.…”

Section: Data Analysis and Discussionmentioning

confidence: 99%

“…The wave vector transfer has only one component which is given by q z = (4π/λ) sin α, where λ denotes the wavelength of the radiation and α the angle between the surface and the x-ray beam. A general description of the x-ray reflectivity technique is given in [18][19][20][21][22][23]. Assuming a simple model consisting of two rough interfaces, i.e.…”

Section: Theory Of X-ray Reflectivitymentioning

confidence: 99%

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The structure of the water–propane interface investigated by x‐ray reflectivity measurements

Paulus

Gutt

Tolan

2008

Surface & Interface Analysis

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We present an x-ray reflectivity study of the propane-water interface.The vertical structure of the interface is analyzed and the adsorption of thin layers of propane on the water surface is observed. An increase of layer thickness with rising pressure is found. The electron density of the thin films is identical with the corresponding value of bulk liquid propane. From the adsorption isotherm we determine the Hamaker constant of the system which shows a considerable higher value compared to calculations based on the Lifshitz theory. The surface tension of the molecularly thin layer is reduced in comparison to the bulk value. The measured surface roughness is in good agreement with a modified model based on capillary wave fluctuations of the water-propane-gas interfaces.

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Section: Data Analysis and Discussionmentioning

confidence: 99%

Section: Theory Of X-ray Reflectivitymentioning

confidence: 99%

The structure of the water–propane interface investigated by x‐ray reflectivity measurements

Paulus

Gutt

Tolan

2008

Surface & Interface Analysis

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“…1) with nearest neighbor distances (center to center) of 58±4 nm, and diameter of 21 ± 5 nm, determined via electron microscopy. After cleaning, samples were dried and loaded into a hermetically sealed environmental chamber under an atmosphere of "ultra-pure" grade N 2 .The environmental chamber as described elsewhere [4,12,15], consisted of two concentric cylindrical metal chambers that allowed extremely stable (drift of < 5 mK/hr) temperature control of the sample with a precision of ±1 mK. Condensation of liquid solvent into the pores was precisely controlled via a positive offset ∆T between the sample temperature, T s and the temper-…”

mentioning

confidence: 99%

“…[4,12,15] Here, H vap = 33.9 kJ/mol is the heat of vaporization of PFMC. [18] For large ∆T , little or no liquid condenses in the pores.…”

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confidence: 99%

Capillary Filling of Anodized Alumina Nanopore Arrays

et al. 2006

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The filling behavior of a room temperature solvent, perfluoro-methyl-cyclohexane, in ∼20 nm nanoporous alumina membranes was investigated in-situ with small angle x-ray scattering. Adsorption in the pores was controlled reversibly by varying the chemical potential between the sample and a liquid reservoir via a thermal offset, ∆T . The system exhibited a pronounced hysteretic capillary filling transition as liquid was condensed into the nanopores. These results are compared with the Kelvin-Cohan prediction, with a prediction in which the effect of the van der Waals potential is combined with the Derjaguin approximation and also with recent predictions by Cole and Saam. [7]; not to mention more commonplace applications such as filtering and humidity sensors [8]. The breadth of nanopore research serves to underscore the need for a solid physical understanding of the evolution of liquids in such systems. Experimental studies have been done on porous network systems, such as the disordered Vycor [9] and M41S silica materials [10]. Unfortunately, these porous systems have very complicated network geometries that make it rather difficult to compare the measurements with simple theoretical predictions. Additionally, most of these studies are done at low temperatures that are impractical for all of the applications described above. Room temperature measurements on ordered nanoporous systems with nearly ideal geometry should provide insight into the physical processes governing liquid behavior in more general nanoporous systems.We describe here in-situ small angle x-ray scattering (SAXS) experiments of the equilibrium wetting and capillary condensation of a room temperature solvent, perfluoro-methyl-cyclohexane (PFMC), within nanoporous alumina (Al 2 O 3 , pore diameter ∼ 20 nm). The anodized alumina system had an ideal geometry described by a parallel arrangement of cylindrical nanopores with large aspect ratios ∼ 1:5,000, see Fig. 1. [11] Experiments were carried out within an environmental chamber that allowed precise control of the amount of solvent condensed within the pores via changes in the chemical potential, ∆µ, relative to liquid/vapor coexistence similar to studies of wetting on flat [12] and nanostructured surfaces [13]. Both adsorption and desorption processes were investigated reproducibly via this technique. Porous alumina membranes were prepared electrochemically using a two-step anodization technique [11,14] and cleaned as described elsewhere [4]. The resultant alumina membrane consisted of an array of cylindrical parallel pores running the entire thickness of the membrane and open on both ends. The macroscopic dimensions of the nanoporous membrane were about 1 cm × 1 cm × 90 microns. Pores formed a 2D local hexagonal order (see Fig. 1) with nearest neighbor distances (center to center) of 58±4 nm, and diameter of 21 ± 5 nm, determined via electron microscopy. After cleaning, samples were dried and loaded into a hermetically sealed environmental chamber under an atmosphere of "ultra-pure" grade N 2 .Th...

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“…Liquid surfaces also provide a unique opportunity to study wetting phenomena on a structure less substrate [4,5]. Specifically they provide a unique opportunity to study the evolution of the liquid -liquid interface as one of the liquids evolves from a thin 2D wetting layer to the bulk liquid [6].…”

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Wetting of hydrocarbon liquid surfaces by fluorocarbon vapor: a microscopic study

Gang

Fukuto

Huber

et al. 2002

Colloids and Surfaces A: Physicochemical and Engineering Aspect

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The wetting of the liquid fluorocarbon (perfluoromethylcyclohexane) on the liquid hydrocarbon (eicosane) surface was studied just above the eicosane melting point, where the eicosane exhibits surface freezing (SF) behavior. The thickness of the wetting layer was controlled by changing the fluorocarbon chemical potential relative to the reservoir through temperature differences DT. The evolution of the microscopic structure of the fluorocarbon layer along the normal-to-surface was measured in situ using X-ray reflectivity. Observed effects include suppression of the SF phase for the thinnest absorbed fluorocarbon layer (d 7 A , ) as well as complete wetting that following the d DT − 1/3 law.

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Quenching of capillary waves in composite wetting films from a binary vapor: An x-ray reflectivity study

Cited by 27 publications

References 60 publications

The structure of the water–propane interface investigated by x‐ray reflectivity measurements

The structure of the water–propane interface investigated by x‐ray reflectivity measurements

Capillary Filling of Anodized Alumina Nanopore Arrays

Wetting of hydrocarbon liquid surfaces by fluorocarbon vapor: a microscopic study

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