Related Experiment Video
Updated: Apr 5, 2026
07:39
Determination of the Excitation and Coupling Rates Between Light Emitters and Surface Plasmon Polaritons
Published on: July 21, 2018
7.4K
Nonradiating anapole modes in dielectric nanoparticles
Andrey E Miroshnichenko1, Andrey B Evlyukhin2,3, Ye Feng Yu4
1Nonlinear Physics Centre, The Australian National University, Acton, Australian Capital Territory 2601, Australia.
Nature Communications
|August 28, 2015
Summary
Dielectric nanoparticles can exhibit a radiationless anapole mode, a nonradiating current configuration. This study demonstrates the anapole mode in visible light by tuning nanoparticle geometry for spectral overlap of dipole moments.
Area of Science:
- Optics and Photonics
- Nanotechnology
- Electromagnetism
Background:
- Nonradiating current configurations are explored as models for stable atoms.
- The anapole mode, a composition of electric and toroidal dipole moments, offers destructive interference of radiation fields.
Purpose of the Study:
- To experimentally demonstrate the anapole mode in dielectric nanoparticles in the visible spectrum.
- To investigate the spectral overlap of toroidal and electric dipole modes through geometric tuning.
Main Methods:
- Fabrication and characterization of dielectric nanoparticles with tunable geometry.
- Spectroscopic analysis to identify spectral overlap of toroidal and electric dipole modes.
- Near-field and far-field scattering measurements to confirm anapole mode excitation.
Main Results:
- Observation of a radiationless anapole mode in dielectric nanoparticles at visible frequencies.
- Achieved spectral overlap of toroidal and electric dipole modes via geometry tuning.
- Detected a significant dip in far-field scattering and characteristic near-field distributions.
Conclusions:
- Dielectric nanoparticles can support radiationless anapole modes in the visible range.
- Anapole physics in nanoparticles opens avenues for studying optical phenomena like reciprocity violation and Aharonov-Bohm effects.
Related Concept Videos
01:28Standing Waves in a Cavity
1.6K
A household microwave and lasers are examples of standing electromagnetic waves in a cavity. When two conducting metal plates are placed parallel at the nodal planes, it creates a cavity where standing waves are formed. The cavity between the two planes is analogous to a stretched string held at the points x = 0 and x = L. Here, the distance 'L' between the two planes must be an integer multiple of half of the wavelength. The wavelengths that satisfy this condition are given by:
1.6K
01:26Diamagnetism
3.4K
Materials consisting of paired electrons have zero net magnetic moments. However, when these materials are placed under an external magnetic field, the moments opposite to the field are induced. Such materials are called diamagnets. Diamagnetism is the response of the diamagnets when placed in an external magnetic field.
Diamagnetism was discovered by Anton Brugmans in 1778 when he observed that bismuth gets repelled by magnetic fields, thus theorizing that diamagnets get repelled by magnets....
Diamagnetism was discovered by Anton Brugmans in 1778 when he observed that bismuth gets repelled by magnetic fields, thus theorizing that diamagnets get repelled by magnets....
3.4K
01:14π Electron Effects on Chemical Shift: Aromatic and Antiaromatic Compounds
2.0K
In aromatic compounds, such as benzene, the circulation of (4n + 2) π-electrons sets up a diamagnetic or diatropic ring current around the perimeter of the molecule. This current induces a magnetic field that opposes the external field inside the ring and reinforces it on the outside. The protons in benzene are deshielded and exhibit high chemical shifts in the range 6.5–8.5 ppm. The shielding effect at the center of the ring is evident in complex aromatic molecules, such as...
2.0K
01:31Dielectric Polarization in a Capacitor
6.5K
The presence of a dielectric medium in a capacitor not only changes the voltage and capacitance but also affects the electric field. In general, dielectrics can be of two types: polar and nonpolar. In a polar dielectric, the positive and negative charges in the molecules are separated by a distance and hence have a permanent dipole moment. In contrast, no such charge separation exists in a nonpolar dielectric, however the nonpolar molecules get polarized in the presence of an external electric...
6.5K
01:23Atomic Nuclei: Nuclear Relaxation Processes
1.4K
In the absence of an external magnetic field, nuclear spin states are degenerate and randomly oriented. When a magnetic field is applied, the spins begin to precess and orient themselves along (lower energy) or against (higher energy) the direction of the field. At equilibrium, a slight excess population of spins exists in the lower energy state. Because the direction of the magnetic field is fixed as the z-axis, the precessing magnetic moments are randomly oriented around the z-axis.
1.4K
01:14Diamagnetic Shielding of Nuclei: Local Diamagnetic Current
1.6K
An applied magnetic field causes the electrons present in the molecule to circulate, setting up a local diamagnetic current within the molecule. The local diamagnetic current arising from circulating sigma-bonding electrons induces a magnetic field, Blocal that opposes the applied magnetic field, B0. The effective magnetic field experienced by these nuclei is given by the difference between the applied and local magnetic fields in a phenomenon called local diamagnetic shielding. Essentially,...
1.6K