Analytical model of the three-dimensional plasmonic ruler

Area of Science:

• Plasmonics and Nanophotonics
• Computational Physics
• Spectroscopy

Background:

• Plasmonic rulers are nanoscale devices used for sensing and imaging.
• Understanding the optical resonances of complex plasmonic structures is crucial for their application.
• Existing methods may lack the precision needed for single-entity structural analysis.

Purpose of the Study:

• To develop a computational model for analyzing the optical resonances of 3D plasmonic rulers.
• To establish a method for encoding and decoding the position of a central nanorod within the ruler using spectral data.
• To demonstrate the potential of this method for high-resolution structural analysis of single molecules.

Main Methods:

• Utilized an electrostatic eigenmode method to model plasmonic coupling between nanoparticles.
• Developed a mathematical framework to link spectral features to the nanorod's spatial coordinates.
• Applied the developed model to analyze experimentally measured scattering spectra.

Main Results:

• The model accurately describes the optical resonances of the 3D plasmonic ruler.
• Key spectral resonances were identified that uniquely encode the horizontal and vertical displacements of the central nanorod.
• The method successfully estimated the nanorod's position from experimental data.

Conclusions:

• The electrostatic eigenmode method provides a robust way to model 3D plasmonic rulers.
• High-resolution spectra from 3D plasmonic oligomers can uniquely encode structural information.
• This approach offers a promising pathway for the structural analysis of single complex macromolecules, DNA scaffolds, proteins, and peptides.