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Full-Text Articles in Physics
Topological Magnetoelectric Effect As Probed By Nanoshell Plasmonic Modes, Railing Chang, Huai Yi Xie, Ya-Chih Wang, Hai-Pang Chiang, P.T. Leung
Topological Magnetoelectric Effect As Probed By Nanoshell Plasmonic Modes, Railing Chang, Huai Yi Xie, Ya-Chih Wang, Hai-Pang Chiang, P.T. Leung
Physics Faculty Publications and Presentations
Axion electrodynamics is applied to study the response of a plasmonic nanoshell with a core made of topological insulator (TI) materials. The electric polarizability of such a system is calculated in the long wavelength limit via the introduction of two scalar potentials satisfying the various appropriate boundary conditions. Our focus is on the topological magneto-electric effect (TME) as manifested in the coupled plasmonic resonances of the nanoshell. It is found that for a TI with broken time-reversal symmetry, such TME will lead to observable red-shifts in the coupled plasmonic modes, with more significant manifestation of such shifts for the bonding …
Förster Resonance Energy Transfer Between Molecules In The Vicinity Of Graphene- Coated Nanoparticles, Tingting Bian, Railing Chang, Pui T. Leung
Förster Resonance Energy Transfer Between Molecules In The Vicinity Of Graphene- Coated Nanoparticles, Tingting Bian, Railing Chang, Pui T. Leung
Physics Faculty Publications and Presentations
The recent demonstration of the plasmonic enhanced Förster resonance energy transfer (FRET) between two molecules in the vicinity of planar graphene monolayers is further investigated using graphene-coated nanoparticles (GNP). Due to the flexibility of these nanostructures in terms of their geometric (size) and dielectric (e.g. core material) properties, greater tunability of the FRET enhancement can be achieved employing the localized surface plasmons. It is found that while the typical characteristic graphene plasmonic enhancements are manifested from using these GNP’s, even higher enhancements can be possible via doping and manipulating the core materials. In addition, the broadband characteristics is further expanded …
Determination Of The Goos-Hänchen Shift In Dielectric Waveguides Via Photo Emission Electron Microscopy In The Visible Spectrum, Theodore Stedmark, Robert Campbell Word, Rolf Kӧnenkamp
Determination Of The Goos-Hänchen Shift In Dielectric Waveguides Via Photo Emission Electron Microscopy In The Visible Spectrum, Theodore Stedmark, Robert Campbell Word, Rolf Kӧnenkamp
Physics Faculty Publications and Presentations
Photoemission Electron Microscopy (PEEM) is a versatile tool that relies on the photoelectric effect to produce high-resolution images. Pulse lasers allow for multi-photon PEEM where multiple photons are required excite a single electron. This non-linear process can directly image the near field region of electromagnetic fields in materials. We use this ability here to analyze wave propagation in a linear dielectric waveguide with wavelengths of 410nm and 780nm. The propagation constant of the waveguide can be extracted from the interference pattern created by the coupled and incident light and shows distinct polarization dependence. The electromagnetic field interaction at the boundaries …
Molecular Fluorescence In The Vicinity Of A Charged Metallic Nanoparticle, H. Y. Chung, P. T. Leung, D. P. Tsai
Molecular Fluorescence In The Vicinity Of A Charged Metallic Nanoparticle, H. Y. Chung, P. T. Leung, D. P. Tsai
Physics Faculty Publications and Presentations
The modified fluorescence properties of a molecule in the vicinity of a metallic nanoparticle are further studied accounting for the possible existence of extraneous charges on the particle surface. This is achieved via a generalization of the previous theory of Bohren and Hunt for light scattering from a charged sphere, with the results applied to the calculation of the various decay rates and fluorescence yield of the admolecule. Numerical results show that while charge effects will in general blue-shift all the plasmonic resonances of the metal particle, both the quantum yield and the fluorescence yield can be increased at emission …
Photoemission From Localized Surface Plasmons In Fractal Metal Nanostructures, Robert Campbell Word, Rolf Könenkamp, T. T. Dornan
Photoemission From Localized Surface Plasmons In Fractal Metal Nanostructures, Robert Campbell Word, Rolf Könenkamp, T. T. Dornan
Physics Faculty Publications and Presentations
We use photoemission microscopy to characterize localized surface plasmon distributions in nanostructured gold layers on indium-tin-oxide/glass substrates. The Au films have a fractal dimension of ∼1.3 and smallest feature sizes of ∼100 nm. We use femtosecond laser pulses at a wavelength of ∼800 nm for the plasmon excitation. Photoelectron emission occurs by a three-photon process in localized areas of indium-tin-oxide with ∼70 nm diameter. In these areas the photoemission rate is enhanced several thousand fold compared to nonstructured surface areas. The results show that plasmon enhanced photoemission can be induced in a nonabsorbing material in proximity to a plasmon-active metal …
High-Resolution Angular Measurement Using Surface-Plasmon-Resonance Via Phase Interrogation At Optimal Incident Wavelengths, Hai-Pang Chiang, Jing-Lun Lin, Railing Chang, Sheng-Yu Su, P.T. Leung
High-Resolution Angular Measurement Using Surface-Plasmon-Resonance Via Phase Interrogation At Optimal Incident Wavelengths, Hai-Pang Chiang, Jing-Lun Lin, Railing Chang, Sheng-Yu Su, P.T. Leung
Physics Faculty Publications and Presentations
It is demonstrated that ultrahigh-resolution angular measurement can be achieved via surface-plasmon-resonance excitation in which the phase difference between p- and s-polarized reflected waves is monitored as a function of the incidence angle. Resolutions down to 1.9 x 10(-6) deg are obtained by performing the measurements at optimal incident wavelengths. This represents an order of magnitude improvement compared with previously reported values.
Frequency Shifts Of Molecules At Rough Metal Surfaces, M. H. Hider, P.T. Leung
Frequency Shifts Of Molecules At Rough Metal Surfaces, M. H. Hider, P.T. Leung
Physics Faculty Publications and Presentations
The frequency shifts for dipolar transitions of molecules at rough metallic surfaces are studied in a phenomenological model following the approach of the authors' previous work [Phys. Rev. B 36, 4664 (1987)], with the surface roughness modeled by a shallow grating profile in most cases. The main findings here are as follows: (1) such surface-induced shifts are indeed observable for molecular frequencies away from the surface-plasmon resonance frequency of the metal; (2) the presence of surface roughness can either enhance or suppress the flat-surface-induced shifts, leading to extra morphology-dependent resonances originated from the radiative coupling between the molecular emission and …