Metal nanoparticles: near and far field manipulation of light
A research tool for nanoscale physics
Nanoscale metal objects possess a localized surface plasmon resonance (LSPR) -- that is, resonant optical light can excite a coherent oscillation of conduction electrons ("plasmon"). This oscillation enhances the local electric field around the nanostructure, and can also influence the properties of other objects located close to the metal structure.
- On fairly short time scales, the plasmon damps out and thereby releases the energy as heat within the nanostructure which through thermal transport processes, propagates outwards from the nanoscale metal object into the surrounding environment; this overall "light-to-heat" conversion process is referred to as a photothermal effect. Our research efforts have recently focused on utilizing such "nano-heater" objects using sample systems when they are intentionally embedded within solid materials and illuminated with appropriate light to excite the LSPR, in order to demonstrate thermal processing outcomes which are unrealizeable by traditional heating means which is typically 1) from the outside of an object to the inside, and 2) not originating from nano-sized structures. We have developed unique (mainly optical-based) research tools to subsequently measure the spatial temperature distribution at nanoscale length scales which arise under such photothermal heating. These efforts mainly employ the unique and robust absorptive properties of the metal nanoparticles themselves, as well as independent signals generated from molecular fluorophores, randomly-distributive within the material matrix.
- Future work will focus on fundamental light-matter interactions by exploring the influence of metal nanoparticles on the emission properties of quasi-resonant light-emitters intenionally placed extremely near the metal nanoparticle while their LSPR is also excited. In this regime, the extremely strong local electric field can dramatically modify the emissive and absorptive properties of the light-emitters. We will separately experiment with both atom-nanoparticle as well as molecule-nanoparticle interactions, in two related, but different realized systems.
"Facile Measurement of Surface Heat Loss from Polymer Thin Films via Fluorescence Thermometry,"
J. Polymer Science, Part B: Polymer Physics 56, 643 (2018).
(journal) [DOI: 10.1002/polb.24571]
"Nanoscale Steady-state Temperature Gradients within Polymer Nanocomposites Undergoing Continuous-Wave Photothermal Heating from Gold Nanorods,"
Nanoscale 9, 11605 (2017).
(journal) [DOI: 10.1039/C7NR04613H]
"In-situ curing of liquid epoxy via gold-nanoparticle mediated photothermal heating,"
Nanotechnology 28, 065601 (2017).
(journal) [paper] [DOI: 10.1088/1361-6528/aa521b]
"Enhanced crystallinity of polymer nanofibers without loss of nanofibrous morphology via heterogeneous photothermal annealing,"
Macromolecules 49, 9484 (2016).
(journal) [paper] [DOI: 10.1021/acs.macromol.6b01655]
"Spatial Temperature Mapping within Polymer Nanocomposites Undergoing Ultrafast Photothermal Heating via Gold Nanorods,"
Nanoscale 6, 15236 (2014).
(journal) [paper] [DOI: 10.1039/C4NR05179C]
(See Publications for a more complete list of papers.)