有机波谱分析双语课件 (33).pdf
拉曼光谱介绍 有机波谱分析 Organic Spectroscopic Analysis Introduction to Raman Spectroscopy Raman SpectroscopyRaman Spectroscopy 拉曼光谱拉曼光谱 Raman Spectroscopy(named after Sir C.V.Raman,who won the Nobel Prize in Physics in 1930)is a spectroscopic technique used to study vibrational,rotational,and other low-frequency modes in a system Raman SpectroscopyRaman Spectroscopy 拉曼光谱拉曼光谱 Chapter 4:Raman Spectroscopy(Chapter 4:Raman Spectroscopy(拉曼光谱拉曼光谱)Raman scattering is an inelastic scattering effect.Raman SpectroscopyRaman Spectroscopy Raman and IR spectra for a given species often resemble one anther quite closely.For Raman spectroscopy the selection rule states that in order for the photon to be absorbed,the molecule must undergo a change in polarizability.Raman Selection RuleRaman Selection Rule IRIR vs Ramanvs Raman Selection RuleSelection Rule IR：Change in Permanent dipole moment（0）Raman：Change in Polorizability（0）Cons and Pros Cons and Pros (advantages and disadvantages)Water does not cause interference.In addition,glass or quartz cells can be employed,thus avoiding the inconvenience of working with sodium chloride.Due to the low intensity of the signals,Raman spectroscopy was not widely used until laser became available in the 1960s.A second deterrent to the general use of Raman spectroscopy was interference by fluorescence.This problem has by now been largely overcome by the use of near-infrared laser sources.1.Raman Spectra of Organic Species Raman spectra yield more information about certain types of organic compounds than do their infrared counterparts.Applications of Raman SpectroscopyApplications of Raman Spectroscopy Raman spectrum of graphene edge,showing the main Raman features,the D,G and G bands Graphene,Fullerene&Carbon Nanotubes 2.Inorganic Species The vibrational energies of metal-ligand bonds are generally in the range of 100 to 700 cm-1,a region of the infrared that is experimentally difficult to study.Applications of Raman SpectroscopyApplications of Raman Spectroscopy 3.Biological Applications The advantages of this technique include the small sample requirement,the minimal sensitivity toward interference by water,the spectral detail,and the conformational and environmental sensitivity.Applications of Raman SpectroscopyApplications of Raman Spectroscopy 4.Surface Enhanced Raman Spectroscopy(SERS)is a surface-sensitive technique that enhances Raman scattering by molecules adsorbed on rough metal surfaces.The enhancement factor can be as much as 1010 to 1011,which means the technique may detect single molecules.Applications of Raman SpectroscopyApplications of Raman Spectroscopy
