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Localized surface plasmon resonance spectroscopy of single silver triangular nanoprisms
Leif J Sherry1, Rongchao Jin, Chad A Mirkin
1Chemistry Department, Northwestern University, Evanston, Illinois 60208-3113, USA.
Nano Letters
|September 14, 2006
Summary
Single silver triangular nanoprisms exhibit strong plasmonic properties, with dipole resonance highly sensitive to shape. These findings offer promising applications in chemical sensing due to exceptional refractive index sensitivity.
Area of Science:
- Plasmonics and Nanophotonics
- Materials Science
- Chemical Sensing
Background:
- Localized surface plasmon resonances (LSPR) in metallic nanoparticles are crucial for optical phenomena.
- Understanding the plasmonic behavior of individual nanostructures is key to developing advanced sensing technologies.
- Silver triangular nanoprisms are of interest due to their unique shape-dependent optical properties.
Purpose of the Study:
- To investigate the plasmonic properties of single silver triangular nanoprisms.
- To characterize the localized surface plasmon resonances (LSPR) and their sensitivity to environmental changes.
- To evaluate the potential of these nanoprisms for chemical sensing applications.
Main Methods:
- Experimental investigation using dark-field optical microscopy and spectroscopy.
- Electrodynamic modeling based on the discrete dipole approximation (DDA) for plasmon excitation assignment.
- Measurement of LSPR sensitivity to refractive index changes and alkanethiol chain length.
Main Results:
- Two distinct LSPR modes (dipolar and quadrupolar) were observed and assigned.
- The intense dipole resonance showed high sensitivity to nanoprism dimensions (height, edge length, tip sharpness).
- High refractive index sensitivity (205 nm RIU(-1)) and a figure of merit (FOM) of 3.3 were achieved.
- Linear response to alkanethiol chain length (4.4 nm/CH2 unit) demonstrated superior short-range sensing capability.
Conclusions:
- Single silver triangular nanoprisms possess tunable and intense plasmonic properties.
- Their high sensitivity to refractive index and molecular chain length makes them excellent candidates for nanoscale chemical sensing.
- The observed performance represents a significant advancement in nanoparticle-based sensing technologies.
