介质微球光场调控制备多级银微纳结构及其表面增强拉曼光谱研究(特邀)  

Photochemical Synthesis Towards Hierarchical Silver Micro-Nanostructures via Dielectric Microspheres for Surface-Enhanced Raman Spectroscopy(Invited)

作　　者：陈冰冰 闫胤洲[1] 赵晨[1] 赵艳[1] 蒋毅坚[1] Chen Bingbing;Yan Yinzhou;Zhao Chen;Zhao Yan;Jiang Yijian(Institute of Laser Engineering,Faculty of Materials and Manufacturing,Beijing University of Technology,Beijing 100124,China)

机构地区：[1]北京工业大学材料与制造学部激光工程研究院,北京100124

出　　处：《中国激光》2024年第4期266-277,共12页Chinese Journal of Lasers

基　　金：国家重点研发计划(2022YFB4600400);国家自然科学基金(12074019);北京市教委科技计划重点项目(KZ202110005002)。

摘　　要：表面增强拉曼光谱(SERS)是一种高灵敏的分子振动指纹光谱技术。光辅助化学还原制备SERS衬底具有成本低、环境适用性强等优势,但在微纳结构多样化制造方面存在局限性,限制了SERS衬底的检出性能。笔者系统研究了介质微球独特的聚焦特性,揭示了微球直径对聚焦光场分布的调控规律,在微球底部实现了可控的光场空间分布,实现了多级银微纳结构的快速光还原合成。进一步,通过优化制备参数(前驱液浓度比、激光辐照功率及辐照时间),成功制备了具有优异拉曼增强效果的多级银纳米颗粒/银微环/介质微球(AgNPs/AgMRs/MS)复合结构。通过介质微球和多级银微纳结构(AgNPs/AgMRs)中的光场耦合,即微球聚焦、多级银微纳结构局域表面等离激元共振以及复合结构定向发射等,实现了10^(-14)mol/L的痕量检测,增强因子可达9.50×10^(9),为光化学还原制备高性能介质-金属复合SERS衬底提供了新思路。Objective Surface-enhanced Raman spectroscopy(SERS)harnesses metallic nanostructures combined with optical fields to create localized surface plasmon resonance(LSPR),yielding significant Raman scattering enhancement.However,top-down manufacturing methods for SERS substrates are often costly due to complex fabrication processes.Photochemical reduction synthesis,known for its high chemical purity and good process controllability,has gained attention but typically requires a high-power laser for rapid preparation.With advancements in high-power femtosecond-pulsed lasers,laser direct-writing has become viable for single-step SERS substrate fabrication.Nevertheless,the small focal laser spot limits efficiency in large-area fabrication of patterned micronanostructures.Dielectric microspheres,with their ability to focus incident lasers at their bottom beyond the diffraction limit,offer a solution for parallel nanomanufacturing.This study developed a one-step photochemical reduction technique for hierarchical silver micro-nanostructures using a dielectric microsphere array,demonstrating its ultra-sensitive Raman detection capability.Methods A polydimethylsiloxane(PDMS)film was prepared by mixing PDMS with a curing agent and then spin-cured.Barium titanate microspheres,with high refractive indices(1.9),were pressed into a monolayer close-packed array on the PDMS film via mechanical grinding.An uncured PDMS film was placed onto this array,transferring and semi-embedding the microspheres into PDMS(PDMS/MS),followed by curing.The PDMS/MS film was then covered with a silver nitrate and trisodium citrate solution.A 532 nm line CW laser,with power ranging from 49‒168μW,focused by PDMS/MS into the solution,induced the reduction reaction.Consequently,Ag+was reduced under focused laser irradiation,forming a hierarchical silver micro-nanostructure(AgNPs/AgMRs)at the bottom of the microspheres.The surface morphology of the Ag micro-nanostructures was examined using SEM.The influence of microsphere diameter and photoreduction para

关 键 词：光谱学 表面增强拉曼光谱 多级银微纳结构 光化学还原 介质微球 

分 类 号：O59[理学—应用物理]