Plasmonic nanoparticles in the quantum size regime
Abstract/Contents
- Abstract
- Nanotechnology development has been majorly driven by the dramatic alteration and emergence of new material properties as dimensions are decreased. In recent years, noble metal nanoparticles have attracted substantial interest owing to their ability to manipulate light on the nanoscale through localized surface plasmon resonances (LSPRs). These collective oscillations of conduction band electrons result in strong optical absorption and scattering in subwavelength structures and enable applications including molecular detection, cancer treatment, and tunable nanoantennas. While the plasmonic properties of individual particles with diameters > 10 nm and multiparticle systems with gap sizes > 1 nm have been experimentally characterized and well-described with classical electrodynamic theory, LSPRs in smaller nanostructures have historically been poorly understood. Experimental observations below these dimensional thresholds have been limited by optical detection and fabrication techniques, precluding analysis of a size regime with the potential for ultrasensitive monitoring and catalysis. This dissertation describes newly-developed approaches to probe plasmonic nanoparticle systems as their dimensions enter the quantum size regime. Our approach relies on scanning transmission electron microscopy (STEM) and electron energy-loss spectroscopy (EELS), which allow high-resolution correlation of plasmonic nanoparticle structure with spectra. First, we explore individual metallic nanoparticles with diameters ranging from 20 nm down to 2 nm. As the particles transition from a classical to a quantum-influenced regime, they reveal substantial resonance shifts that deviate from classical electrodynamic predictions. An analytical quantum mechanical model is developed to explain this divergence as function of altered particle permittivity, accounting for the discretization of energy states as particle diameter decreases. Next, resonantly-coupled multiparticle systems including dimers and trimers are discussed. Using a novel electron beam manipulation technique, the separation distance between adjacent particles can be reduced to Angstrom scales. Experimental EELS analysis of dimers reveals non-classical spectral trends and that closely correlate with state-of-the-art quantum models incorporating electron tunneling. Trimers are additionally found to support a greater variety of resonant modes through selective electron beam excitation, and demonstrate both classical and non-classical spectral evolution at sub-nanometer gaps. The study of these quantum-influenced single and multiparticle systems will inform the design of future ultrafine plasmonic sensors, as well as support new interdisciplinary exploration bridging molecular electronics, nonlinear optics, and plasmonics.
Description
| Type of resource | text |
|---|---|
| Form | electronic; electronic resource; remote |
| Extent | 1 online resource. |
| Publication date | 2015 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Associated with | Scholl, Jonathan Andrew |
|---|---|
| Associated with | Stanford University, Department of Materials Science and Engineering. |
| Primary advisor | Dionne, Jennifer Anne |
| Thesis advisor | Dionne, Jennifer Anne |
| Thesis advisor | Brongersma, Mark L |
| Thesis advisor | Salleo, Alberto |
| Advisor | Brongersma, Mark L |
| Advisor | Salleo, Alberto |
Subjects
| Genre | Theses |
|---|
Bibliographic information
| Statement of responsibility | Jonathan Andrew Scholl. |
|---|---|
| Note | Submitted to the Department of Materials Science and Engineering. |
| Thesis | Thesis (Ph.D.)--Stanford University, 2015. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2015 by Jonathan Andrew Scholl
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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