超短激光脉冲作用下等离激元“相变”特性研究

Phase Transition of Plasmons Induced by Ultrashort Laser Pulses

研究了金纳米颗粒在超短激光脉冲作用下发生的形貌变化,以及由此导致的局域化表面等离激元共振光谱的变化,即"相变"效应。利用化学合成的金纳米颗粒胶体制备由随机分布的金纳米颗粒阵列构成的薄膜。将飞秒激光脉冲作用于薄膜表面,监测激光作用前后样品的显微结构图像和消光光谱的变化。实验结果表明:金纳米颗粒在激光脉冲作用下发生微区熔融、团聚等物理过程,导致金纳米颗粒形貌发生变化和等离激元共振光谱红移。

This study investigates the morphological modification of gold nanoparticles using ultrashort laser pulses and subsequent changes in the resonance spectra of localized surface plasmon polaritons(LSPPs)known as phase transition.A thin film comprising a random array of gold nanoparticles is prepared using chemically synthesized colloidal gold nanoparticles.When the femtosecond laser pulse is irradiated on the film surface,changes are observed in the microscopic image and the extinction spectrum before and after laser irradiation.The measurement results show that the femtosecond laser pulses induce the melting and aggregation of the gold nanoparticles in some microscopic areas,leading to a morphological change of the gold nanoparticles and a red-shift in the plasmonic resonance spectra.