Laser-assisted generation of elongated Au nanoparticles and subsequent dynamics of their morphology under pulsed irradiation in water and calcium chloride solutions

TL;DR

This study demonstrates the laser-assisted creation and dynamic morphological evolution of elongated gold nanoparticles in water and calcium chloride solutions, revealing their formation, fragmentation, and agglomeration under pulsed laser irradiation.

Contribution

It introduces a novel experimental approach for synthesizing elongated gold nanoparticles and analyzing their behavior under pulsed laser exposure in aqueous solutions.

Findings

Elongated Au nanoparticles exhibit longitudinal plasmon resonance in the red and near IR spectrum.

Laser irradiation causes initial agglomeration into chains, followed by fragmentation.

The process is influenced by laser pulse energy and exposure time.

Abstract

One-step laser generation of Au elongated nanoparticles (NPs) and their successive fragmentation and agglomeration are experimentally studied for the first time. In the present work, laser-assisted formation of Au elongated nanoparticles by ablation of a solid Au (99.99%) target in water was done using a ytterbium-doped fiber laser sources with pulse duration of 200 ns and pulse energy of 1mJ. Extinction spectrum correlating with TEM shows the appearance of absorption signal in red region and near IR-spectrum that corresponds to longitudinal plasmon resonance of electrons in elongated Au NPs. In addition, generated elongated Au nanoparticles were exposed to pulsed laser beam with various pulse energy and laser exposure time. It was found that at early stages of irradiation NPs agglomerate as the NPs chains with size of order of 1 micrometer long. Further laser exposure results in fragmentation of these chains. Possible processes of laser-assisted formation of elongated Au NPs in aqueous solutions of calcium chloride and their subsequent interaction with pulsed laser irradiation are discussed.