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单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,(,s,urface,e,nhanced,R,aman,s,pectroscopy),SERS,Raman spectroscopy:,high characteristic,good spatial resolution (micro Raman),minimal sample prep,a,ration,all solvents can be used,but:,biological samples often show high fluorescence,biological molecules appear often at low concentration level,Why SERS spectroscopy?,SERS quenches fluorescence,Raman,silver colloids,M,. x,piperita,514.5 nm,2000,1500,1000,500,Wavenumber,/ cm,-1,Raman Intensity,SERS improves the detection limit: Adenine,10,-8,M,10,-7,M,10,-6,M,10,-5,M,10,-3,M,10,-2,M,10,-1,M,1500,1000,500,Raman Intensity,Raman,Wavenumber / cm,-1,1500,1000,500,Wavenumber / cm,-1,Raman Intensity,SERS,How does SERS work? The SERS EM enhancement,E,O,metal colloid,excitation,detection,SERS,molecule,SERS EM enhancement shape effect,SERS: Excitation of,plasmon,resonances in Ag (Au or Cu),nanoparticles,Raman spectroscopy utilizes optical properties of nanostructures,Wavelength nm,SCS nm,J. Kottmann,et al., IFH Field Theory Group,ETH Zrich,Ag, Au or Cu,Wavelength/nm,Scattering Cross section,Field,enhancement,SERS: Raman spectroscopy,util,i,zes,optical properties of nanostructures,J. Kottmann,et al., IFH Field Theory Group,ETH Zrich,Wavelength nm,SCS nm,*10,SERS EM enhancement shape effect,Wavelength/nm,Field,enhancement,Scattering Cross section,SERS: Raman spectroscopy,util,i,zes,optical properties of nanostructures,20 nm,J. Kottmann,et al., IFH Field Theory Group,ETH Zrich,Ag, Au or Cu,SERS EM enhancement aggregation effect,Field,enhancement,400,200,100,50,20,10,5,2,1,0.5,0.2,Scattering Cross section,Wavelength/nm,Typical SERS media,不同形状金纳米粒子的表面增强拉曼光谱,自组装好的不同形状的金纳米粒子的硅片浸没在,20mM,NaSCn,的溶液里,取出后测量其,SERS,信号,以,SCN -,作为探针分子,绿光,(514,1,5nm),作为激发光波长得到的,SERS,谱图,各种过渡金属表面上吸附的吡啶在最强峰电位下的表面增强拉曼谱图,Near-Field Microscopy,Rayleigh Limit,Near-field resolution,从拉曼光谱获取的信息,characteristic Raman peak,Composition and structure of material,changes in frequency of Raman peak,stress/strain state,Crystal size,polarization of Raman peak,crystal (molecule) symmetry and orientation,width of Raman peak,quality of,crystal(crystal,size),十四,拉曼光谱的主要应用,不同的物质，其拉曼谱是不同的，就象人的指纹一样，因此拉曼光谱可用于物相的分析与表征。,拉曼光谱在催化中的应用,拉曼光谱能提供催化剂本身以及表面上物种的结构信息，这是认识催化剂和催化反应最为重要的信息。,拉曼光谱较容易实现原位条件下,(,高温、高压，复杂体系,),的催化研究。,拉曼光谱可以用于催化剂制备的研究，特别是可以对催化剂制备过程从水相到固相的实时研究。,拉曼光谱可以实现时间分辨动力学和动态学的研究。,提出的,ZrO,2,相变机理,UV Laser,X-ray,UV Raman Scattering,XRD,Visible Laser,Visible Raman Scattering,Amorphous Zr(OH),4,Tetragonal ZrO,2,Monoclinic ZrO,2,紫外拉曼光谱与,XRD,，可见拉曼光谱结果的不同表明氧化锆四方相到单斜相的相变首先是从表面开始，接着逐步发展到体相。,拉曼光谱的一些特点,1,不同物质其拉曼光谱是不同的，就象人的指纹一样，可用于光谱表征。,2,拉曼位移（即入射光与散射光的波数差）与入射光的波长无关，与振动或转动能级相对应，拉曼位移的数值从几个波数,4000,波数。,3,斯托克斯线和反斯托克斯线对称地分布与瑞利线的两侧，通常是测斯托克斯线,4,拉曼散射与分子所处的状态无关,
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