03/11/2017

Femtosecond laser reshaping yields gold nanorods with ultranarrow surface plasmon resonances

Title: Femtosecond laser reshaping yields gold nanorods with ultranarrow surface plasmon resonances
Authors:

Guillermo González-Rubio, Pablo Díaz-Núñez, Antonio Rivera, Alejandro Prada, Gloria Tardajos, Jesús González-Izquierdo, Luis Bañares, Pablo Llombart, Luis G. Macdowell, Mauricio Alcolea Palafox, Luis M. Liz-Marzán, Ovidio Peña-Rodríguez, Andrés Guerrero-Martínez

Journal: Science 2017, 358, 640-644

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.