Super-Resolution Imaging Techniques in Plasmonic Nanostructures

Super-resolution imaging in plasmonic nanostructures has emerged as a powerful approach to probe electromagnetic interactions at the nanoscale, surpassing the diffraction limit of conventional optical microscopy. By exploiting localised surface plasmon resonances in metallic nanostructures, researchers can generate intense near-field enhancements or “hotspots” that modulate the emission and absorption properties of nearby fluorophores. Techniques such as single-molecule localisation microscopy, stimulated emission depletion (STED), and stochastic optical reconstruction microscopy (STORM) have been adapted to capture spatial maps of field intensity, local density of optical states (LDOS) and radiative decay rates with spatial resolution down to a few nanometres. These methods offer unparalleled insight into Purcell-effect enhancements, image-dipole distortions and coupled emitter–antenna dynamics. Practical applications range from nanoscale biosensing and chemical imaging by surface-enhanced Raman spectroscopy (SERS), to guiding the design of quantum-optical components and next-generation photonic devices.

Research from Nature Portfolio

Recent studies have quantitatively demonstrated how plasmonic coupling can shift the apparent position of single emitters by tens of nanometres. By arranging fluorophores at defined separations from gold nanoparticles using DNA origami, one investigation revealed systematic lateral displacements in single-molecule localisation maps, a phenomenon termed the “single-molecule mirage.” This work underlines the necessity of accounting for near-field coupling when interpreting super-resolution images in plasmonic environments. Another study introduced a spectrally decoupled localisation strategy employing emitters with large Stokes shifts to separate the excitation and emission processes. This approach enabled independent mapping of the enhanced excitation field or the LDOS around metallic nanoantennas with nanometre precision, thereby disentangling contributions from field strength and emission–antenna coupling in super-resolution localisations.

Super-Resolution Imaging Techniques in Plasmonic Nanostructures publication trend

The graph below shows the total number of articles in super-resolution imaging techniques in plasmonic nanostructures across all publications each year (not limited to Nature Index journals).

Technical terms

Localised surface plasmon (LSP): Collective oscillation of conduction electrons in a metallic nanoparticle excited by light, leading to intense local electromagnetic fields.

Local density of optical states (LDOS): Measure of the number of electromagnetic modes available for emission at a given position and frequency near a nanostructure.

Super-resolution localisation microscopy: Family of fluorescence techniques (PALM, STORM) that determine emitter positions with nanometre precision by stochastically activating fluorophores.

Image dipole effect: Distortion of an emitter’s radiation pattern due to the induced mirror charge in a nearby metallic surface.

Stokes shift: Difference in wavelength between the peaks of a fluorophore’s absorption and emission spectra, used to decouple excitation and emission processes.

Surface-enhanced Raman spectroscopy (SERS): Technique exploiting plasmonic hotspots to amplify Raman scattering signals for chemical and biological sensing.

References

1. Shifting molecular localization by plasmonic coupling in a single-molecule mirage. Nature Communications (2017).
2. Decoupling absorption and emission processes in super-resolution localization of emitters in a plasmonic hotspot. Nature Communications (2017).
3. Superresolution imaging of the local density of states in plasmon lattices. Optica (2016).
4. Towards a full characterization of a plasmonic nanostructure with a fluorescent near-field probe.. Optics Express (2013).