培训课件-X射线荧光分析导论.ppt

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1、X射线荧光分析导论电子波谱1Hz-1kHz1kHz-1014Hz1014Hz-1015Hz1015Hz-1021Hz超低频率电磁波无线电波微波红外线可见光伽马射线紫外线LowenergyHighenergyX射线Theory入射X射线轰击原子的内层电子，如果能量大于它的吸收边，该内层电子被驱逐出整个原子（整个原子处于高能态，即激发态）。较高能级的电子跃迁、补充空穴，整个原子处于低能态，即基态。由高能态转化为低能态，释放能量。ΔE=Eh-El.能量将以X射线的释放，产生X射线荧光。TheHardwareSourcesOpticsFilter

2、s&TargetsDetectorsSourcesEndWindowX-RayTubesSideWindowX-RayTubesRadioisotopesOtherSourcesScanningElectronMicroscopesSynchrotronsPositronandotherparticlebeamsEndWindowX-RayTubeX-rayTubesVoltagedetermineswhichelementscanbeexcited.Morepower=lowerdetectionlimitsAnodeselection

3、determinesoptimalsourceexcitation(applicationspecific).SideWindowX-RayTubeBeWindowSiliconeInsulationGlassEnvelopeFilamentElectronbeamTarget(Ti,Ag,Rh,etc.)CopperAnodeHVLeadRadioisotopesIsotopeFe-55Cm-244Cd-109Am-241Co-57Energy(keV)5.914.3,18.322,8859.5122Elements(K-lines)A

4、l–VTi-BrFe-MoRu-ErBa-UElements(L-lines)Br-II-PbYb-PuNonenoneWhileisotopeshavefallenoutoffavortheyarestillusefulformanygaugingapplications.OtherSourcesSeveralotherradiationsourcesarecapableofexcitingmaterialtoproducex-rayfluorescencesuitableformaterialanalysis.ScanningElec

5、tronMicroscopes(SEM)–Electronbeamsexcitethesampleandproducex-rays.ManySEM’sareequippedwithanEDXdetectorforperformingelementalanalysisSynchotrons-ThesebrightlightsourcesaresuitableforresearchandverysophisticatedXRFanalysis.PositronsandotherParticleBeams–Allhighenergypartic

6、lesbeamsionizematerialssuchthattheygiveoffx-rays.PIXEisthemostcommonparticlebeamtechniqueafterSEM.SourceModifiersSeveralDevicesareusedtomodifytheshapeorintensityofthesourcespectrumorthebeamshapeSourceFiltersSecondaryTargetsPolarizingTargetsCollimatorsFocusingOpticsSourceF

7、iltersFiltersperformoneoftwofunctionsBackgroundReductionImprovedFluorescenceDetectorX-RaySourceSourceFilterFilterTransmissionCurve%TRANSMITTEDENERGYLowenergyx-raysareabsorbedAbsorptionEdgeX-raysabovetheabsorptionedgeenergyareabsorbedVeryhighenergyx-raysaretransmittedTiCrT

8、itaniumFiltertransmissioncurveThetransmissioncurveshowsthepartsofthesourcespectrumaretransmitted