拉曼光谱分析法课件.pptVIP

拉曼光谱分析法刘和文

RemoteRamanAnalysisonPlanetaryMissionslToallowRamanspectroscopyatrangeof10sofmeters.lThisNASA-fundedprojectisaimedatMarslandersorlandersonotherplanets,butalsohasterrestrialuses.

激光拉曼光谱基本原理h(?-??)Rayleigh散射：弹性碰撞；激发虚态0E+h?100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；E+h?0h?0h?h?+??0h?00E1E0V=1V=0h??Rayleigh散射Raman散射E基态，E振动激发态；E+h?，E+h?激发虚态；010010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）

基本原理E+h?101.Raman散射Raman散射的两种跃迁能量差：E+h?20h(?+??)h(?-??)00h?0?E=h(?-??)0E产生stokes线；强；基态分子多；1V=1h??E0V=0?E=h(?+??)0产生反stokes线；ANTI-STOKESSTOKES弱；Raman位移：Raman散射光与入射光频率差??；Rayleigh?+???0?0-??0

Rayleigh/RamanTransitionsIRAbsorptions

Rayleigh/RamanTransitionsandSpectra

Rayleigh/RamanTransitionsandSpectra

TheSpectrumAcompleteRamanspectrumconsistsof:?aRayleighscatteredpeak(highintensity,samewavelengthasexcitation)?aseriesofStokes-shiftedpeaks(lowintensity,longerwavelength)?aseriesofanti-Stokesshiftedpeaks(stilllowerintensity,shorterwavelength)?spectrumindependentofexcitationwavelength(488,632.8,or1064nm)SpectrumofCCl,usinganArlaserat488nm.+4

RamanSpectroscopyAnotherspectroscopictechniquewhichprobestherovibrationalstructureofmolecules.C.V.Ramandiscoveredin1928;receivedNobelPrizein1931.Canprobegases,liquids,andsolids.Mustusealasersourceforexcitation.Resurgenceinrecentyearsduetothedevelopmentofnewdetectorswithimprovedsensitivity.ShiftbackawayfromFT-RamantodispersiveRamanwithmultichanneldetectorsystems.

InfraredandRamanSpectraofBenzeneIRRaman

拉曼光谱与红外光谱分析方法比较

SomeRamanAdvantagesHerearesomereasonswhysomeonewouldprefertouseRamanSpectroscopy.?Non-destructivetosamples(minimalsampleprep)?Highertemperaturestudiespossible(don’tcareaboutIRradiation)?Easilyexaminelowwavenumberregion:100cm-1readilyachieved.?Bettermicroscopy;usingvisiblelightsocanfocusmoretightly.?Easysample