713 research outputs found
Optical transparency of mesoporous metals
We examine the optical properties of metals containing a periodic arrangement
of nonoverlapping spherical mesopores, empty or filled with a dielectric
material. We show that a slab of such a porous metal transmits light over
regions of frequency determined by the dielectric constant of the cavities and
the fractional volume occupied by them, with an efficiency which is many orders
of magnitude higher than predicted by standard aperture theory. Also, the
system absorbs light efficiently over the said regions of frequency unlike the
homogeneous metal.Comment: 9 pages in total, 3 figures To be published in Solid State
Communication
On wave propagation in inhomogeneous systems
We present a theory of electron, electromagnetic, and elastic wave
propagation in systems consisting of non-overlapping scatterers in a host
medium. The theory provides a framework for a unified description of wave
propagation in three-dimensional periodic structures, finite slabs of layered
structures, and systems with impurities: isolated impurities, impurity
aggregates, or randomly distributed impurities. We point out the similarities
and differences between the different cases considered, and discuss the
numerical implementation of the formalism.Comment: 12 page
Scattering of elastic waves by elastic spheres in a NaCl-type phononic crystal
Based on the formalism developed by Psarobas et al [Phys. Rev. B 62,
278(2000)], which using the multiple scattering theory to calculate properties
of simple phononic crystals, we propose a very simple method to study the
NaCl-type phononic crystal. The NaCl-type phononic crystal consists of two
kinds of non-overlapping elastic spheres with different mass densities,
coefficients and radius following the same periodicity of the
ions in the real NaCl crystal. We focus on the (001) surface, and view the
crystal as a sequence of planes of spheres, each plane of spheres has identical
2D periodicity. We obtained the complex band structure of the infinite crystal
associated with this plane, and also calculated the transmission, reflection
and absorption coefficients for an elastic wave (longitudinal or transverse)
incident, at any angle, on a slab of the crystal of finite thickness.Comment: 15 pages, 6 figure
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Simulation for field emission images of micrometer-long SWCNTs
The electron distribution of open-ended single-walled carbon nanotubes with
chirality indexes (7,0) and (5,5) in the field emission conditions was
calculated via a multi-scaled algorithm. The field emission images were
produced numerically. It was found that the emission patterns change with the
applied macroscopic field. Especially, the symmetry of the emission pattern of
the (7,0) carbon nanotube is breaking in the lower field but the breaking is
less obvious in the higher field. The enlargement factor increases with the
applied macroscopic field.Comment: 8 pages, 4 figure
Viscoelastic response of sonic band-gap materials
A brief report is presented on the effect of viscoelastic losses in a high
density contrast sonic band-gap material of close-packed rubber spheres in air.
The scattering properties of such a material are computed with an on-shell
multiple scattering method, properties which are compared with the lossless
case. The existence of an appreciable omnidirectional gap in the transmission
spectrum, when losses are present, is also reported.Comment: 5 pages, 4 figures, submitted to PR
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