Resumen de Femtosecond laser reshaping yields gold nanorods with ultranarrow surface plasmon resonances

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

• 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.