702 research outputs found
Unstable topography of biphasic surfactant monolayers
We study the conformation of a heterogeneous surfactant monolayer at a
fluid-fluid interface, near a boundary between two lateral regions of differing
elastic properties. The monolayer attains a conformation of shallow, steep
`mesas' with a height difference of up to 10 nm. If the monolayer is
progressively compressed (e.g. in a Langmuir trough), the profile develops
overhangs and finally becomes unstable at a surface tension of about K(delta
c_0)^2, where (delta c_0) is the difference in spontaneous curvature and K a
bending stiffness. We discuss the relevance of this instability to recently
observed folding behavior in lung surfactant monolayers, and to the absence of
domain structures in films separating oil and water in emulsions.Comment: 7 pages, 7 figures, LaTex using epl.cls, accepted for Europhys Let
Evolution of a bosonic mode across the superconducting dome in the high-Tc cuprate Pr(2-x)Ce(x)CuO(4-{\delta})
We report a detailed spectroscopic study of the electron doped cuprate
superconductor Pr(2-x)Ce(x)CuO(4-{\delta}) using point contact junctions for
x=0.125(underdoped), x=0.15(optimally doped) and x=0.17(overdoped). From our
conductance measurements we are able to identify bosonic resonances for each
doping. These excitations disappear above the critical temperature, and above
the critical magnetic field. We find that the energy of the bosonic excitations
decreases with doping, which excludes lattice vibrations as the paring glue. We
conclude that the bosonic mediator for these cuprates is more likely to be spin
excitations.Comment: 4 page
Kinetics of Particles Adsorption Processes Driven by Diffusion
The kinetics of the deposition of colloidal particles onto a solid surface is
analytically studied. We take into account both the diffusion of particles from
the bulk as well as the geometrical aspects of the layer of adsorbed particles.
We derive the first kinetic equation for the coverage of the surface (a
generalized Langmuir equation) whose predictions are in agreement with recent
simulation results where diffusion of particles from the bulk is explicitly
considered.Comment: 4 page
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