Demixing transition in a quasi-two-dimensional surface-frozen layer.
A thin/thick transition was observed by x-ray reflectivity in a surface-frozen crystalline bilayer on the surface of a molten binary mixture of long alcohols. This rare example of a solid-solid phase transition in a quasi-2D system is shown to result from an abrupt temperature-driven change in the layer's composition, kinetically enabled by the layer's ability to exchange molecules with the underlying 3D liquid bulk. Mean-field thermodynamics yields a Gibbs-adsorption-like expression which accounts very well for the transition.
Physics Department, Bar Ilan University, Ramat Gan 52900, Israel.
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Sloutskin
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Gang
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Kraack
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Ocko
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Sirota
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