报告题目

Deposition of nanoparticle metal films using nanosecond and femtosecond lasers

报 告 人

Prof.James G. Lunney, School of Physics and CRANN, Trinity College Dublin, Dublin, Ireland

报告地点

物理楼中 212

报告时间

3月13日下午3:00-4:00

联 系 人

王树峰（54990）

报告摘要

Pulsed laser deposition (PLD) is a relatively simple technique for the preparation of metal nanoparticle (NP) films which are free from chemical contamination. I will describe the results of some recent work on PLD of metal NP films using both between nanosecond (ns) and femtosecond (fs) lasers.We have studied the dynamics of both the plasma and nanoparticle ablation plumes using Langmuir probe, optical emission spectroscopy and time-resolved optical absorption. In ns PLD ablation plume is strongly ionized and the NPs form by surface diffusion on the substrate. In fs PLD a smaller fraction of the ablated material is removed as a plasma plume moving at ~106 cm s-2,and a larger fraction leaves the target as a hot nanoparticle mist moving at ~2×104 cm s-2.We describe both the optical emission and absorption properties of the nanoparticle mist by taking account of the wavelength dependence of the nanoparticle emissivity. The energy efficiencies of ns and fs laser ablation were measured and the ablation plume dynamics were compared. For silver NP distributions were measured using transmission electron microscopy; in both cases the mean particle size was found to increase as the equivalent solid-density thickness of the deposit increased. The films displayed the expected surface plasmon resonance in the visible optical spectrum. We have benchmarked the SERS performance of these sliver NP films against a commercial substrate.