Femtosecond laser reshaping yields gold nanorods with ultranarrow surface plasmon resonances

Abstract

The irradiation of gold nanorod colloids with a femtosecond laser can be tuned to induce controlled nanorod reshaping, yielding colloids with exceptionally narrow localized surface plasmon resonance bands. The process relies on a regime characterized by a gentle multishot reduction of the aspect ratio, whereas the rod shape and volume are barely affected. Successful reshaping can only occur within a narrow window of the heat dissipation rate: Low cooling rates lead to drastic morphological changes, and fast cooling has nearly no effect. Hence, a delicate balance must be achieved between irradiation fluence and surface density of the surfactant on the nanorods. This perfection process is appealing because it provides a simple, fast, reproducible, and scalable route toward gold nanorods with an optical response of exceptional quality, near the theoretical limit.

Near‐Infrared Light‐Triggered Dual Drug Release Using Gold Nanorod‐Embedded Thermosensitive Nanogel‐Crosslinked Hydrogels

“…AuNRs provide two obvious absorption bands in their UV–vis spectrum (Figure S1, Supporting Information). The absorption band at ≈800 nm is derived from the longitudinal surface plasmon resonance (LSPR) absorption of the AuNRs . The AuNRs have dimensions of (59.2 ± 2.5) nm × (21.5 ± 1.3) nm (Figure S2, Supporting Information).…”

Photothermal Heating and Cooling of Nanostructures

“…The photothermal excitation of inorganic nanostructures has attracted as ignificant amount of interesti nr ecent years due to applicationsi nt he opticala blation of solid tumors, [1][2][3] the theory of hot Brownian motion, [4] the modification of metal nanostructures, [5,6] the production of contrasta gents, [7] the optical printing of materials, [8,9] the growth of semiconductor nanowires, [10][11][12][13][14] nanoscale photophoretic propulsion, [15,16] the thermala ctuation of myosin Vm otor proteins, [17] and, recently, the laser cooling of nanomaterials. [18,19] Electromagnetic theory and analyticalh eat transport solutions exist or are under development to describe many of thesea pplications.…”

Spatiotemporal Heterogeneity of Reactions in Solution Observed with High‐Speed Single‐Nanorod Rotational Sensing

“…In addition, the local fluidic environment of pure water was found to be non-uniform in time and space.This technique could be applied to study other chemical and biochemical reactions in solution.The reaction mechanisms in nanoscopic systems often differ considerably in time and space due to their structural and dynamic heterogeneity, [1] so it is imperative to develop effective methods capable of following spatiotemporal changes directly at the single-particle level, [2] especially for nanoscale catalysts and self-propelled micro/nanomotors in complex fluidic surroundings.T oa void important intermediates and rare events being masked by ensemble-averaged measurements,p eople have established an umber of techniques that can monitor the activity and chemical states of single nanoparticles (NPs) under reaction conditions, [3] including single-molecule fluorescence imaging, [4] tipenhanced Raman spectroscopy, [5] surface plasmon resonance imaging, [6] and electrochemical methods. Awide range of viscosities from 237 cP to 0.8 cP could be detected conveniently.W e studied H 2 O 2 decomposition reactions that were catalyzedb y AuNRs coated with Pt nanodots (AuNR@PtNDs) and observed two different rotational states.T he two states and their transitions are related to the production and the amalgamation of O 2 nanobubbles on the nanorod surface depending on H 2 O 2 concentration.…”

“…Awide range of viscosities from 237 cP to 0.8 cP could be detected conveniently.W e studied H 2 O 2 decomposition reactions that were catalyzedb y AuNRs coated with Pt nanodots (AuNR@PtNDs) and observed two different rotational states.T he two states and their transitions are related to the production and the amalgamation of O 2 nanobubbles on the nanorod surface depending on H 2 O 2 concentration. In addition, the local fluidic environment of pure water was found to be non-uniform in time and space.This technique could be applied to study other chemical and biochemical reactions in solution.The reaction mechanisms in nanoscopic systems often differ considerably in time and space due to their structural and dynamic heterogeneity, [1] so it is imperative to develop effective methods capable of following spatiotemporal changes directly at the single-particle level, [2] especially for nanoscale catalysts and self-propelled micro/nanomotors in complex fluidic surroundings.T oa void important intermediates and rare events being masked by ensemble-averaged measurements,p eople have established an umber of techniques that can monitor the activity and chemical states of single nanoparticles (NPs) under reaction conditions, [3] including single-molecule fluorescence imaging, [4] tipenhanced Raman spectroscopy, [5] surface plasmon resonance imaging, [6] and electrochemical methods. [7] Nevertheless,s o far these techniques have only been applied to nanoparticles immobilized on as olid substrate,w here the interfacial microenvironment and the information obtained on the reaction may not be the same as those in the homogeneous solution.Due to their high brightness and great photostability, plasmonic nanoparticles have been used recently as nonfluorescent single-particle optical probes.…”

“…The reaction mechanisms in nanoscopic systems often differ considerably in time and space due to their structural and dynamic heterogeneity, [1] so it is imperative to develop effective methods capable of following spatiotemporal changes directly at the single-particle level, [2] especially for nanoscale catalysts and self-propelled micro/nanomotors in complex fluidic surroundings.T oa void important intermediates and rare events being masked by ensemble-averaged measurements,p eople have established an umber of techniques that can monitor the activity and chemical states of single nanoparticles (NPs) under reaction conditions, [3] including single-molecule fluorescence imaging, [4] tipenhanced Raman spectroscopy, [5] surface plasmon resonance imaging, [6] and electrochemical methods. [7] Nevertheless,s o far these techniques have only been applied to nanoparticles immobilized on as olid substrate,w here the interfacial microenvironment and the information obtained on the reaction may not be the same as those in the homogeneous solution.…”