Related Experiment Video
Updated: Mar 21, 2026
15:06
Measurement of Scattering Nonlinearities from a Single Plasmonic Nanoparticle
Published on: January 3, 2016
13.5K
Optical Fano resonances in a nonconcentric nanoshell
Applied Optics
|May 4, 2016
Summary
An off-center core in metal nanoshells generates all multipoles, enabling analytical calculation of Fano resonance. This configuration also boosts electric field enhancement for improved surface-enhanced sensing applications.
Area of Science:
- Plasmonics
- Nanophotonics
- Computational Electromagnetics
Background:
- Metal nanoshells exhibit unique optical properties due to surface plasmon resonances.
- The position of the core within the nanoshell influences its electromagnetic response.
- Understanding multipole generation is crucial for tailoring nanoshell behavior.
Purpose of the Study:
- To analytically derive matrix elements for multipole expansion coefficients in off-center core nanoshells.
- To investigate the coupling between dipole and quadrupole terms leading to Fano resonance.
- To quantify the electric field enhancement by an off-center core for sensing applications.
Main Methods:
- Analytical derivation of matrix elements for multipole expansion.
- Theoretical analysis of dipole-quadrupole coupling.
- Finite-element method (FEM) simulations for validation.
Main Results:
- Analytical solutions for multipole expansion coefficients were obtained.
- Explicit demonstration of dipole-quadrupole coupling causing Fano resonance.
- Significant increase in electric field enhancement at the shell surface compared to concentric nanoshells.
Conclusions:
- The off-center core configuration provides a pathway to engineer Fano resonances in metal nanoshells.
- Enhanced electric fields offer potential for highly sensitive surface-enhanced sensing.
- Analytical and numerical methods confirm the multipole solutions and their implications.
Related Concept Videos
01:14NMR Spectrometers: Resolution and Error Correction
1.1K
When magnetic nuclei in a sample achieve resonance and undergo relaxation, the signal detected in NMR is an approximately exponential free induction decay. Fourier transform of an exponential decay yields a Lorentzian peak in the frequency domain. Lorentzian peaks in an NMR spectrum are defined by their amplitude, full width at half maximum, and position, where the peak width is governed by the spin-spin relaxation time alone. In real experiments, however, the applied magnetic field is rendered...
1.1K
01:14Sound Waves: Resonance
3.6K
Resonance is produced depending on the boundary conditions imposed on a wave. Resonance can be produced in a string under tension with symmetrical boundary conditions (i.e., has a node at each end). A node is defined as a fixed point where the string does not move. The symmetrical boundary conditions result in some frequencies resonating and producing standing waves, while other frequencies interfere destructively. Sound waves can resonate in a hollow tube, and the frequencies of the sound...
3.6K
01:02¹H NMR: Interpreting Distorted and Overlapping Signals
1.7K
Spin systems where the difference in chemical shifts of the coupled nuclei is greater than ten times J are called first-order spin systems. These nuclei are weakly coupled, and their chemical shifts and coupling constant can generally be estimated from the well-separated signals in the spectrum.
As Δν decreases and the signals move closer, the doublets appear increasingly distorted. The intensities of the inner lines increase at the cost of those of the outer lines as the signals are...
As Δν decreases and the signals move closer, the doublets appear increasingly distorted. The intensities of the inner lines increase at the cost of those of the outer lines as the signals are...
1.7K
01:05Atomic Nuclei: Magnetic Resonance
1.4K
The number of nuclear spins aligned in the lower energy state is slightly greater than those in the higher energy state. In the presence of an external magnetic field, as the spins precess at the Larmor frequency, the excess population results in a net magnetization oriented along the z axis. When a pulse or a short burst of radio waves at the Larmor frequency is applied along the x axis, the coupling of frequencies causes resonance and flips the nuclear spins of the excess population from the...
1.4K