29- photochemistry

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1、Spectroscopy&PHotochemistryGeneralChemistryI,LectureSeries29ZhijunNingReading:OGC7§20图片部分来自网络和米启兮课件LightSourcesIntensityMeasuringIntensityEnergyMicrowaveprobesInfrareddetectorCharge-coupleddevicePhotodiodeFilm(CCD)光电二极管IntensityPrinciplesofSpectroscopyConservationofenergy:Energyhν=ΔEConserva

2、tionofangularmomentum:l=c/nEBΔL=±h/2πΔL=±h/2π2s2p12/28/2016GeneralChemistryI,ShanghaiTech4IntensitySpectralIntensityEnergyEI∝N−N,N∝exp−Selectionrules选律i→fifkTB2s2pOutline•PrinciplesofSpectroscopy•Experimentaltechniques•Theoreticalbasis•DifferentTypesofSpectroscopy•Atomic•Rotation

3、al&vibrational•Electronic•Nuclearmagneticresonance•Photochemistry12/28/2016GeneralChemistryI,ShanghaiTech6AtomicEmissionSpectroscopyPlasma等离子体AtomicEmissionSpectroscopy(2)NeNaCaHe,Rb,Cs,Tl,andmanyelementswerediscoveredbyAESAtomicAbsorptionSpectroscopyHigherintensityLowerintensitymorephotonsl

4、essphotons单色光器12/28/2016GeneralChemistryI,ShanghaiTech9AtomicAbsorptionSpectroscopy单色光器=NumberofatomsOutline•PrinciplesofSpectroscopy•Experimentaltechniques•Theoreticalbasis•DifferentTypesofSpectroscopy•Atomic•Rotational&vibrational•Electronic•Nuclearmagneticresonance•Photochemistry12/28/201

5、6GeneralChemistryI,ShanghaiTech11RotationalSpectroscopyδ−EBΔL=±h/2πδ+δ+MomentumofinertiaI=mr2Selectionrules转动惯量RotationalenergyE=½Iω2hν=ΔE转动能kΔL=±h/2πAngularmomentumL=Iω角动量QuantizedRotationClassicalQuantumJ=3ωJhL=IωL=J(J+1)2πp2L21h2Ek=2mor2IE=Iω2E=2J(J+1)k2k8πIhEk=hBJ(J+1),B=8π2IE=hBJ(J+1)k1

6、2/28/2016GeneralChemistryI,ShanghaiTech14RotationalSpectrumofCO透过率波数2B≈30÷8≈3.8cm−1=114GHzhB=2I=mr28πIVibrationalSpectroscopyδ−δ+PotentialenergyE=½kA2振动势能pVibrationalfrequencyk/mν=振动频率2π12/28/2016GeneralChemistryI,ShanghaiTech16QuantizedVibrationClassicalQuantumxv1E=kx2Ep=h(ν+1)p2Selectionru

7、leshν=ΔEΔv=±1VibrationalSpectroscopyofCO~2000cm−1COgas2143cm−1PolyatomicMoleculesRamanactivePolarizabilitychangeIRactiveDipolemomentchangeIRactiveDipolemomentchange12/28/2016GeneralChemistryI,ShanghaiTech19Dec.30:Photochemistry,NuclearChemistryRead