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Vibrational Anharmonicity and Energy Relaxation in Nanoscale Acoustic Resonators
Cameron Wright1, Gregory V Hartland1
1Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States.
Nano Letters
|November 20, 2023
Summary
Anharmonicity in gold nanoplate vibrations was observed. Organic layers coupled to the nanoplates reduced overtone frequencies, enabling control over vibrational lifetimes in nanostructures.
Area of Science:
- Nanophotonics and Plasmonics
- Materials Science
- Vibrational Spectroscopy
Background:
- Gold nanoplates exhibit unique vibrational properties.
- Understanding vibrational anharmonicity is crucial for controlling nanostructure dynamics.
- Transient absorption microscopy is a powerful tool for studying ultrafast phenomena.
Purpose of the Study:
- To investigate the fundamental and overtone vibrations of gold nanoplates.
- To explain the observed anharmonicity in nanoplate vibrations.
- To explore the role of organic layers in modulating vibrational lifetimes.
Main Methods:
- Transient absorption microscopy was employed to study gold nanoplate vibrations.
- A continuum mechanics model incorporating organic layers was developed.
- Experimental and calculated quality factors were compared.
Main Results:
- The n=3 overtone frequencies were found to be less than three times the fundamental frequency, indicating significant anharmonicity.
- The continuum mechanics model successfully explained the anharmonicity through coupling between the gold nanoplate and organic layers.
- Comparison of experimental and calculated quality factors revealed coupling primarily to the top organic layer.
Conclusions:
- Anharmonicity in gold nanoplate vibrations arises from coupling with surrounding organic layers.
- Engineering soft organic layers around metal nanostructures offers a method to control vibrational lifetimes.
- This work provides insights into damping mechanisms and vibrational energy dissipation in nanoplasmonic systems.
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