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1、X射線熒光分析導(dǎo)論電子波譜1Hz-1kHz1kHz-1014Hz1014Hz-1015Hz1015Hz-1021Hz超低頻率電磁波無(wú)線電波微波紅外線可見(jiàn)光伽馬射線紫外線LowenergyHighenergyX射線Theory入射X射線轟擊原子的內(nèi)層電子，如果能量大于它的吸收邊，該內(nèi)層電子被驅(qū)逐出整個(gè)原子（整個(gè)原子處于高能態(tài)，即激發(fā)態(tài)）。較高能級(jí)的電子躍遷、補(bǔ)充空穴，整個(gè)原子處于低能態(tài)，即基態(tài)。由高能態(tài)轉(zhuǎn)化為低能態(tài)，釋放能量。ΔE=Eh-El.能量將以X射線的釋放，產(chǎn)生X射線熒光。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
