基于自组装纳米金单层膜的全内反射SERS研究.pdf

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1、物理化学学报(WuliHuaxueXuebao)JulyActaP．一Chim．Sin．2014，30(7)，1201—12071201【Article]doi：10．3866／PKU．WHXB2Ol405191www．whxb．pku．edu．cn基于自组装纳米金单层膜的全内反射SERS研究赵乔逯丹凤刘德龙陈晨胡德波祁志美(中国科学院电子学研究所，传感技术国家重点实验室，北京100190)摘要：采用静电自组装技术分别在玻璃基片和30nm厚的金膜表面固定一层金纳米粒子(GNP)制得两种表面增强拉曼散射(SERS)基底，然后通过棱镜全内反射(TIR)激励和背向收集模式分别测试了两种基

2、底上吸附的染料单分子层SERS光谱．实验结果表明两种SERS基底的拉曼增强效果均高度依赖于入射激光的偏振状态，对于玻璃，纳米金SERS基底，s光全内反射导致的拉曼增强因子是线偏振光(p)光的2-5倍，说明该基底上的“热点”位于纳米金单层膜内相邻粒子之间对于玻璃／金膜／纳米金SERS基底，只有采用P光在特定的全内反射角下才能激发SERS信号，而且测得的SERS信号比玻璃，纳米金基底增强了近3O倍．究其原因是P光在金膜表面共振激发的传播表面等离子体与纳米金局域表面等离子体耦合，进而导致显著场增强．实验结果指出在背向收集模式下，由P光激发的SERS信号是非偏振光，包含强度几乎相等的s和p

3、成分．利用玻璃／金膜／纳米金基底还实现了拉曼光定向发射和收集，测得的SERS信号是P光．关键词：纳米金单层膜全内反射；表面增强拉曼散射；偏振状态；背向收集定向发射中图分类号：0647StudyofTotalInternalReflectionSERSBasedonSelf-AssembledGoldNanoparticleMonolayerF_ImZHAOQiaoLUDan—FengLIUDe—LongCHENChenHUDe—BoQIZhi—Mei(StateKeyLaboratoryofTransducerTechnology,InstituteofElectronics,Ch

4、ineseAcademyofScience,Beijing10019~PR．China)Abstract：TwotypesofSurfaceEnhancedRamanSca~edng(SERS)substmteswerepreparedbyself-assemblyofgoldnanoparticle(GNP)monolayersf¨moneitherbareglasssubstrates(glass／GNP)orglasssubstrateswitha30nmthickgoldfiImfglass／Au／GNP)．SERSspectraofdyemoleculesadsorbed

5、onthetwosubstrateswereobtainedbytotaIinternalretiection(TIR1ofanexcitationlaserbeamcombinedwithcollectionoftheair-sidesigna1．TheexperimentalresultsdemonstratedthatthesignaIenhancementfactorsofthetwoSERSsubstratesgreatlydependonthepolarizationstateoftheexcitationbeam．Inthecaseoftheglass／GNPsubs

6、trate．thesignalenhancementfactorobtainedwiththes—polarizationTlRistwotofivetimesashigherasthatobservedwiththep-polarizationTIR，indicatingtheformationof“hotspots”betweenadiacentparticlesintheGNPmonolayer．Withtheglass／Au／GNPsubstrate．theSERSsignaIcanbeexcitedonlybyP—polarizationTlRataspecificret

7、iectionangle．andtheair．sideSERSsignaIisalmost30timesthatobtainedwiththeglass／GNPsubstrate．Thefindingssuggestthatsignificantfieldenhancementisinducedbythecouplingbetweenpropagatingsurfaceplasmonresonance(SPR)andthelocalizedSPRwithinthegl