Modeling anisotropic plasmon excitations in self-assembled fullerenes

Abstract

The plasmon excitations in Coulomb-coupled spherical two-dimensional electron gases (S2DEGs) reveal an interesting dependence on the displacement vector between the centers of the spheres with respect to the axis of quantization for the angular momentum quantum number L. Specifically, plasmon modes for a bundle of three S2DEGs have been obtained within the random-phase approximation (RPA). The inter-sphere Coulomb interaction matrix elements and their symmetry properties were also investigated in detail. The case of a bundle gives an adequate picture of the way in which the Coulomb interaction depends on the orbital angular momentum quantum number L and its projection M . We concluded that the interaction between the S2DEGs aligned at an angle of 45 o with the axis of quantization is negligible compared to the interaction along and perpendicular to the quantization axis, which are themselves unequal to each other. Consequently, the plasmon excitation frequencies reveal an interesting orientational anisotropic coupling to an external electromagnetic field probing the charge density oscillations. Our result on the spatial correlation may be experimentally observable. In this connection, there have already been some experimental reports pointing to a similar effect in nanoparticles.

Nonlocal plasma spectrum of graphene interacting with a thick conductor

“…1-4 has covered fundamental aspects such as nonlocality 5 , quantum effects in nanoscale structures including fullerene [6][7][8] , graphene 9,10 , carbon nanotubes 11,12 , silicene 13,14 and metallic dimers 15 , surface plasmon lasing 16 , plasmon-electron interaction 17 and the potential role played by plasmon excitations in electronic sensors 18,19 and radiation degradation of electronic and optoelectronic devices 20 . The surge in activity to understand and discover novel plasmonic materials is stimulated by possible applications such as light concentration for solar energy 21 , devices for telecommunications 22 , and near-field instrumentation 23 .…”

Plasmon dissipation in gapped graphene open systems at finite temperature

“…(9) is no longer valid after introducing the graphene-conductor Coulomb coupling in the open system, we have to include both the real and imaginary parts of Im Π (0) T (q, ω; µ) in Eq. (19) and find the dissipation rates corresponding to each plasmon branch. We know from Eq.…”

“…Consequently, graphene is expected to have several potential device applications in transistors, optics, microscopy and nanolithography [13][14][15] . These studies on graphene plasmonics also extend to other carbon-based structures, such as fullerenes [16][17][18][19][20][21] , carbon nanotubes 22,23 , and especially recently discovered silicon-based silicene and other buckled honeycomb lattice structures 24,25 with on-site potential differences between sublattices.…”

Coulomb excitations for a short linear chain of metallic shells

“…In such a system, the strength of the interaction between different nano shells varies with their separation as well as the relative orientation of the line joining their centers. With this in mind, it makes sense to distinguish the present investigation from both cases of a triad arranged at the vertices of a right-angle triangle [9] or an infinite linear array of periodically placed S2DEGs [10]. The assembly under consideration is shown schematically in Fig.…”

“…The LEG may be obtained in a multilayer semiconductor system by epitaxial growth such as GaAs/AlGaAs or in a type-II system such as GaSb AlSb InAs quantum-well structures containing an electron and a hole gas layer in each unit cell [3]. Another class of nanostructures for which the Coulomb excitations have been studied is the spherical 2DEG (S2DEG) [4][5][6] which has been employed in modeling metallic dimers [7,8], clusters of carbon nanoparticles [9] and metallic chains of gold nanoparticles [10,11]. However, since the spherical geometry allows for possible anisotropic coupling (unlike the cylindrical geometry [12,13]) with an external light source by employing far-field polarization spectroscopy [11], the Coulomb excitations for the S2DEG allow for more variation in frequency than the 2DEG by employing shells of different radii, forming finite length chains with adjustable nearest-neighbor separations, or using bundles arranged in assorted configurations.…”