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1、X-rayPhotoelectronSpectroscopy(XPS)SurfaceAnalysisTheStudyoftheOuter-MostLayersofMaterials(<100?).ElectronSpectroscopiesXPS:X-rayPhotoelectronSpectroscopyAES:AugerElectronSpectroscopyEELS:ElectronEnergyLossSpectroscopyIonSpectroscopiesSIMS:SecondaryIonMass
2、SpectrometrySNMS:SputteredNeutralMassSpectrometryISS:IonScatteringSpectroscopyIntroductionto X-rayPhotoelectronSpectroscopy(XPS)X-rayPhotoelectronSpectroscopySmallAreaDetectionX-rayBeamX-raypenetrationdepth~1mm.Electronscanbeexcitedinthisentirevolume.X-ray
3、excitationarea~1x1cm2.ElectronsareemittedfromthisentireareaElectronsareextractedonlyfromanarrowsolidangle.1mm210nmXPSspectrallinesareidentifiedbytheshellfromwhichtheelectronwasejected(1s,2s,2p,etc.).Theejectedphotoelectronhaskineticenergy:KE=hv-BE-?Followi
4、ngthisprocess,theatomwillreleaseenergybytheemissionofanAugerElectron.ConductionBandValenceBandL2,L3L1KFermiLevelFreeElectronLevelIncidentX-rayEjectedPhotoelectron1s2s2pThePhotoelectricProcessLelectronfallstofillcorelevelvacancy(step1).KLLAugerelectronemitt
5、edtoconserveenergyreleasedinstep1.ThekineticenergyoftheemittedAugerelectronis:KE=E(K)-E(L2)-E(L3).ConductionBandValenceBandL2,L3L1KFermiLevelFreeElectronLevelEmittedAugerElectron1s2s2pAugerRelationofCoreHoleXPSEnergyScaleTheXPSinstrumentmeasuresthekinetice
6、nergyofallcollectedelectrons.TheelectronsignalincludescontributionsfrombothphotoelectronandAugerelectronlines.KE=hv-BE-?specWhere:BE=ElectronBindingEnergyKE=ElectronKineticEnergy?spec=SpectrometerWorkFunctionPhotoelectronlineenergies:Dependentonphotonenerg
7、y.Augerelectronlineenergies:NotDependentonphotonenergy.IfXPSspectrawerepresentedonakineticenergyscale,onewouldneedtoknowtheX-raysourceenergyusedtocollectthedatainordertocomparethechemicalstatesinthesamplewithdatacollectedusinganothersource.XPSEnergyScale-K
8、ineticenergyXPSEnergyScale-BindingenergyBE=hv-KE-?specWhere:BE=ElectronBindingEnergyKE=ElectronKineticEnergy?spec=SpectrometerWorkFunctionPhotoelectronlineenergies:NotDependentonphotonenergy.Augerelectronline
