《拉曼光谱分析法》PPT课件

《《拉曼光谱分析法》PPT课件》由会员上传分享，免费在线阅读，更多相关内容在教育资源-天天文库。

1、拉曼光谱分析法RemoteRamanAnalysisonPlanetaryMissionsToallowRamanspectroscopyatrangeof10'sofmeters.ThisNASA-fundedprojectisaimedatMarslandersorlandersonotherplanets,butalsohasterrestrialuses.激光拉曼光谱基本原理Rayleigh散射：弹性碰撞；无能量交换，仅改变方向；Raman散射：非弹性碰撞；方向改变且有能量交换；Rayleigh散射Raman散

2、射E0基态，E1振动激发态；E0+h0，E1+h0激发虚态；获得能量后，跃迁到激发虚态.（1928年印度物理学家RamanCV发现；1960年快速发展）hE0E1V=1V=0h0h0h0h0+E1+h0E0+h0h(0-)激发虚态基本原理1.Raman散射Raman散射的两种跃迁能量差：E=h(0-)产生stokes线；强；基态分子多；E=h(0+)产生反stokes线；弱；Raman位移：Raman散射光与入射光频率差；ANTI-STOKES0-RayleighS

3、TOKES0+0h(0+)E0E1V=1V=0E1+h0E2+h0hh0h(0-)Rayleigh/RamanTransitionsIRAbsorptionsRayleigh/RamanTransitionsandSpectraRayleigh/RamanTransitionsandSpectraTheSpectrumAcompleteRamanspectrumconsistsof:•aRayleighscatteredpeak(highintensity,samewavelengthase

4、xcitation)•aseriesofStokes-shiftedpeaks(lowintensity,longerwavelength)•aseriesofanti-Stokesshiftedpeaks(stilllowerintensity,shorterwavelength)•spectrumindependentofexcitationwavelength(488,632.8,or1064nm)SpectrumofCCl4,usinganAr+laserat488nm.RamanSpectroscopyAnot

5、herspectroscopictechniquewhichprobestherovibrationalstructureofmolecules.C.V.Ramandiscoveredin1928;receivedNobelPrizein1931.Canprobegases,liquids,andsolids.Mustusealasersourceforexcitation.Resurgenceinrecentyearsduetothedevelopmentofnewdetectorswithimprovedsensit

6、ivity.ShiftbackawayfromFT-RamantodispersiveRamanwithmultichanneldetectorsystems.InfraredandRamanSpectraofBenzeneIRRaman拉曼光谱与红外光谱分析方法比较SomeRamanAdvantagesHerearesomereasonswhysomeonewouldprefertouseRamanSpectroscopy.•Non-destructivetosamples(minimalsampleprep)•Hig

7、hertemperaturestudiespossible(don’tcareaboutIRradiation)•Easilyexaminelowwavenumberregion:100cm-1readilyachieved.•Bettermicroscopy;usingvisiblelightsocanfocusmoretightly.•Easysampleprep:waterisanexcellentsolventforRaman.Canprobesamplethroughtransparentcontainers(

8、glassorplasticbag).WatchforFluorescenceSpectrumofanthracene.A:usingAr+laserat514.5nm.B:usingNd:YAGlaserat1064nm.Wanttouseshortwavelengthbecausescatteringdepend