拉曼测量的是什么？光散射- 瑞利散射散射光中，弹性(瑞利) 散射占主导前…后…散射光与入射光有相同的频率光散射- 拉曼散射光中的1010光子之一是非弹性散射（拉曼）前…后…光损失能量，使分子振动Information obtained from Raman spectroscopy 拉曼光谱的信息拉曼光谱的特点和主要困难拉曼散射信号弱（比荧光光谱平均小2－3数量级）。激光激发强。拉曼信号频率离激光频率很近。激光瑞利散射比拉曼信号强1010－1014，对拉曼信号干扰很大。拉曼光谱仪器的设计，必须能排除瑞利散射光，并具有高灵敏度（体现在弱信号检测的高信噪比），才能有效地收集拉曼谱。高灵敏度高灵敏度高稳定性、重复性高稳定性、高重复性雷尼绍拉曼光谱仪的传动部件使用了世界领先的RG2 线形和圆形编码器，克服了机械间隙。能够给光谱仪带来空间与光谱的高稳定性高重复性高精度与高准确度高稳定性、高重复性带编码器控制的自动平台重复性: ± 0.2 μm，较无编码器控制的自动平台提高了10倍步长: 0.1 μm (x- and y-axes)1 μm (z-axis) 高稳定性、高重复性圆形编码器控制的光栅转动台技术直接测量转动角度，同时编码器精密伺服控制其转动，而非采用计量马达转过多少圈的办法确保光栅转动的精确性和重复性。高重复性、高稳定性某条原子发射线随光栅24小时转动的位置重复性实验结果细节; 间隔30分钟的抖动是由于室内空调的启动与关闭引起的凌晨2点钟时的最大偏差是由外部环境空气温度最低造成的尽管是在温差较大的办公室环境（而非温度控制的实验室环境）最大偏离也不过0.06 cm-1 高稳定性、高重复性同步连续扫描专利技术同步连续扫描专利技术同步连续扫描专利技术共焦原理Non-confocal Confocal 共焦应用:高分子样品的深度分布Sample 2 μm thick polyethylene (PE) film Thick polypropylene(PP) substrate Laser 633 nm HeNe Spectrometer settings Slit width 10 μm Conditions x50 objective focus down through sample from PE to PP Results weak PP features seen on PE spectrum strength increases until only PP seen 共焦应用- 石英内的气、液包裹体数字化显微共焦技术的优点：不需要额外的透镜，信号透过率高操作简单、灵活深度共焦的效果：完全可以达到深度分辨率2微米Sample - SiO2 pattern on Si substrate Sample - SiO2 pattern on Si substrate Scan over a sharp edge, intensity variation shows lateral resolution 激光扩束技术 空间分辨率可达至理论衍射极限激光功率衰减以及激光功率密度连续变化激光功率衰减以及激光功率密度连续变化激光功率衰减以及激光功率密度连续变化自动化程度高CCD 芯片尺寸的选择CCD 芯片尺寸的选择Renishaw inVia Series Typical Competitor 芯片：EEV 576x398 EEV 1024x256 芯片宽度：12.7 mm 25.6mm 由上图可见，CCD 芯片越宽，边缘处光斑像差越大，选择小尺寸芯片可以避免像差。分辨率/灵敏度的选择扩展功能强Raman/SEM 将SEM 的高清晰的空间分辨率与拉曼光谱有效结合SEM 性能不受影响可测紫外-可见-近红外的拉曼与发光光谱可测磷光光谱可与低真空与高真空装置联用可与能谱联用Sample application - materials science 材料科学Diamond - top spectrum Silicon carbide - lower spectrum Benefits Enhanced spatial resolution (NSOM) Enhanced sample imaging (AFM), same area analysis Combined software for AFM/Raman image acquisition and overlay. Nanonics NSOM/AFM 100 Renishaw Microscope Custom software linking Nanonics and Renishaw packaged (Cavendish Instruments Ltd). Stress and phases 功能扩展能力强Raman /FTIR Raman/FTIR 二者可以互补原位测量红外与拉曼光谱（同一个样品点）为FT-IR 提供了高品质的光学像. The confocality of a Raman instrument can be demonstrated by moving a sample for Raman analysis through the microscope best white light focus. A measure of the Raman intensity as a function of distance from best white light focus shows the efficiency of collecting out of plane light. An excellent material for testing confocality is Ge. Ge was chosen because the sample is not transparent, and all Raman light must originate from the surface. This testing arrangement (use of an opaque sample) eliminates the complication of compensating for refractive indices of a transparent sample to determine the true confocal depth resolution. The confocality of the collection optics should not be confused with the ability of the microscope optics to focus to a diffraction limited spot at the sample, or the matching of the collection optic to the spectrometer optics. A good rule of thumb is that when the back aperture of the objective is matched by with a similarly sized gaussian laser beam, the focused spot size is: 1.22 * laser wavelength . media refractive index * numerical aperture Consider (in air)	best focus	slit image size 100X (NA 0.95)	 0.66	 21 (3 mm back aperture) 50X (NA 0.75)		 0.84	 13 20X (NA 0.40)		 1.57	 13 10X (NA 0.25)		 2.51	 13 5X (NA 0.10)		 6.81	 13 Liquid and gas inclusions in quartz 数字化显微共焦系统专利技术quartz H2O CO2 CH4 N2 4 数字化显微共焦系统专利技术科学家评价：“Using these slits instead of pinholes makes it easier to make the optical alignments needed for confocal Raman measurements.”(K.Ajito & K. Torimitsu, NTT Japan “Trends in Analytical Chemistry”, 20, 2001) 数字化显微共焦系统专利技术Raman microscopy: Confocal basics The system laser focus beam waist (dl) is determined by: 1) Excitation wavelength: l 2) Microscope objective focal length : f 3) Effective laser beam diameter at the the objective backaperture: Dl Lateral spatial resolution 显微镜样品双瑞利滤光片狭缝光栅扩束器激光CCD 检测器雷尼绍拉曼光谱仪光路结构示意图优势6. 1. 16级激光功率缜密衰减（可从100%至5 x10-8%）2. 采用激光扩束器技术，可以连续改变激光焦点处光斑大小（1-250微米），进而可以连续改变作用于样品上的功率密度注：激光功率过高或者激光功率密度过高，有的样品可能被烧，也有的样品虽然不会破坏，但在激光加热下，会产生应力，导致拉曼峰的移动，影响了实验结果的准确性。激光功率16级衰减激光扩束扩束扩束器控制键优势7. 自动化程度高激光光路计算机控制、调节、存储激光光路的位置激光光路可自动准直激光波长可自动切换等等部件瑞利滤光片自动切换光栅可自动切换狭缝大小可自动调节等等功能共焦与非共焦可自动切换取谱模式与观察样品模式可自动切换自动切换激光的16级衰减模式等等优势8. 选择了最佳成像质量的CCD 芯片尺寸为什么Renishaw 可以选择小尺寸芯片？因为有专利保护的连续扫描技术，可以保证连续获取任意宽波段范围的光谱最新的显微共焦系统专利技术优势9. 可以选择的仪器分辨率/灵敏度分辨率和灵敏度是一对矛盾，分辨率提高的同时，灵敏度将会下降。分辨率和多种因素有关，不仅仅取决于焦长。在Renishaw 的仪器上，用户可根据所研究的样品来选择分辨率和灵敏度，既可选择高分辨率，也可选择高灵敏度最新的显微共焦系统专利技术Sample/Application determines required system resolution 咖啡的拉曼光谱相同的激光功率分辨率~7 cm-1 ( 光栅600 l/mm) 分辨率~1 cm-1 ( 光栅2400 l/mm) Single static scan with 600 l/mm, 10 stitched static scans with 2400 l/mm 10 秒60秒分辨率/灵敏度的选择功能扩展能力强优势10. 功能扩展能力强可与扫描电镜（电子探针，能谱，阴极荧光）联用可与原子力显微镜/近场光学联用可与付立叶红外光谱仪联用可与共聚焦扫描显微镜联用注意：若需要联用功能，可随时升级扩展功能强Raman/SEM 扩展功能强Raman/AFM/NSOMSEM University of Sheffield, Dept Chemistry 扩展功能强Raman/AFM/NSOM 14 mm University of Sheffield, Dept Chemistry 扩展功能强Raman/AFM/NSOM First of all, I would like to briefly remind you what’s the principle of the Raman effect. To get a Raman spectrum, one uses a laser source that emits photons that will for some of them interact with the molecules of the investigated compound. During this interaction, their is a transfer of energy from the photons to the sample molecules, that will induce vibrations of the molecular bonding. A radiation is then re-emitted by the compound that presents frequency shifts, directly correlated with the amount o energy that has been transferred from the photons to the different molecules. The resulting information is exhibited under the form of a spectrum that can be seen as a spectral fingerprint, with along the Y axis the absolute intensity and along the X axis the relative frequency shifts. The Raman technique presents various advantages that are highly valuable as for the analysis of illicit substances : - a Raman analysis does not require in most cases any sample preparation - it is fast and non destructive so that other analysis can be performed afterwards on the same specimen - it is highly selective * apply innovation * Vibrational States 振动能级i Ground State 基级Virtual State 虚能级Real States 真实能级Mid IR Stokes Raman Rayleigh Anti-Stokes Raman Fluorescence 红外斯托克斯拉曼瑞利散射反斯托克斯拉曼荧光入射光分子分子散射光excitation emission 入射光分子excitation 分子振动散射光excit.- vib. emission 拉曼光谱的优点和特点对样品无接触，无损伤；样品无需制备；快速分析，鉴别各种材料的特性与结构；能适合黑色和