Critical adsorption in the undersaturated regime

Desai, Niraj S.; Peach, Sarah; Franck, Carl

doi:10.1103/physreve.52.4129

Cited by 35 publications

(25 citation statements)

References 20 publications

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“…For comparison we added surface energy difference of the two liquid components [26], as solid lines the theoretical predictions for the seal-while other approaches tried to connect the surface field ing functions for ( --) and ( -+) BC. As can be seen, with the difference in the chemical potential [30]. We the measured values for 1J lie in between these limiting hope that our work will stimulate further theoretical cases.…”

Section: Tc -T)-" ~=~Omentioning

confidence: 51%

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Tunability of critical Casimir interactions by boundary conditions

2009

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-We experimentally demonstrate that critical Casimir forces in colloidal systems can be continuously tuned by the choice of boundary conditions. The interaction potential of a colloidal particle in a mixture of water and 2,6-lutidine has been measured above a substrate with a gradient in its preferential adsorption properties for the mixture's components. We find that the interaction potentials at constant temperature but different positions relative to the gradient continuously change from attraction to repulsion. This demonstrates that critical Casimir forces respond not only to minute temperature changes but also to small changes in the surface properties.In 1978 Fisher and de Gennes pointed out that if two objects are immersed in a fluid close to its critical point, long-ranged forces due to confined critical fluctuations act between their surfaces [1]. Such critical Casimir forces arise due to the confinement of fluctuations in the order parameter of the fluid between the objects. In the case of e.g. a classical binary liquid mixture close to its demixing point, the order parameter corresponds to the concentration difference between the two components of the mixture. The strength and range of critical Casimir forces is set by the fluid's bulk correlation length ξ which diverges upon approaching the critical temperature T C . Therefore, close to T C , the interaction strongly depends on the temperature as has been recently confirmed in several experiments [2][3][4][5][6][7][8][9].In addition to their temperature dependence, critical Casimir forces are very sensitive to the boundary conditions (BC) which are determined by the adsorption preferences of the mixture's components at the confining surfaces: not only the magnitude, but even the sign of critical Casimir interactions can be altered by corresponding symmetric or asymmetric BC. So far, theoretical studies largely concentrated on BC, where one species of molecules in the binary liquid mixture forms a saturated monolayer at the confining surfaces [10,11]. Depending on whether both surfaces strongly adsorb the same (−−) or different species (−+), this results in attractive or repulsive (a)

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Section: Tc -T)-" ~=~Omentioning

confidence: 51%

“…, the surface in this representation. With increasing ~x the scaling field h1 which is often used to theoretically describe functions change systematically from negative to posi-continuously varying BC [29][30][31]. Ellipsometry studies on tive values.…”

Section: Tc -T)-" ~=~Omentioning

confidence: 99%

Tunability of critical Casimir interactions by boundary conditions

2009

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“…(6). One of them is hyperuniversality of the amplitude analogous in our work to the amplitude Cj in Eq.…”

Section: Introductionmentioning

confidence: 95%

“…Usual critical behavior of confined thermodynamic systems may essentially change with respect to standard surface universality classes [1] such as the ordinary (O), the ex traordinary (E), and the special or the "surface-bulk" (SB) one [2] when they are subjected to changeable boundary conditions (BCs) [3,4], Manifestly different critical behavior of relevant universal quantities and laws governing them was also supported by experiments [5][6][7] referring to systems with tunable BCs. It turns out that systems driven from (0,E,SB) surface universality classes have very interesting and rich behavior in wide crossover regions situated among (0,E,SB) fixed points.…”

Section: Introductionmentioning

confidence: 99%

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Crossover aspects in Ising strips under the influence of variable surface fields and a grain boundary

Borjan

2015

Phys. Rev. E

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I use an exact variational formulation of Mikheev and Fisher to study the critical Ising strip with a grain boundary and confining surfaces characterized by arbitrary and different surface magnetic fields. Energy density profiles that serve as order parameters of the system within the used method show strong nonmonotonous behavior in the vicinity of confining surfaces. I consider short-distance expansion of energy density profiles. New universal amplitudes associated with distant-wall corrections exhibit nontrivial crossover behaviors from positive to negative values as the field's variables are continuously varied. Casimir amplitudes calculated in a self-contained manner are characterized by complex manifolds which may comprise two disconnected positive wings separated by an area of negative values. I define and determine the generalized de Gennes-Fisher amplitude, which strongly suggests that a stress tensor is present within one of the distant-wall corrections. This is an unanticipated result given that a similar discovery for standard extraordinary (E) and ordinary (O) surface universality classes was based on the conformal invariance symmetry, which is broken under the present boundary conditions. A grain boundary essentially influences both energy density profiles and Casimir amplitudes, besides surface fields with a number of accompanying features that are examined in detail. We present closed analytic forms of energy density profiles for standard (N) and (O) BCs: ɛNN(x,g),ɛOO(x,g),ɛNO(x,g) [(N) is the normal surface universality class, g is the grain boundary's strength, x is the relative distance x:=z/L with L as a film width], thus enabling us to deduce their important symmetry properties and to have a detailed insight into their general behaviors.

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Surfaces and Interfaces of Fluids, Structure of

Schlossman

2003

Digital Encyclopedia of Applied Physics

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Critical adsorption in the undersaturated regime

Cited by 35 publications

References 20 publications

Tunability of critical Casimir interactions by boundary conditions

Tunability of critical Casimir interactions by boundary conditions

Crossover aspects in Ising strips under the influence of variable surface fields and a grain boundary

Surfaces and Interfaces of Fluids, Structure of

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