培訓(xùn)課件X射線熒光分析導(dǎo)論

電子波譜1Hz-1kHz

1kHz-1014Hz

1014Hz-1015Hz

1015Hz

-1021Hz

超低頻率電磁波無線電波

微波紅外線可見光

伽馬射線紫外線LowenergyHighenergyX射線

本文檔共66頁；當(dāng)前第1頁；編輯于星期日\12點6分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)逐出整個原子（整個原子處于高能態(tài)，即激發(fā)態(tài)）。較高能級的電子躍遷、補充空穴，整個原子處于低能態(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。本文檔共66頁；當(dāng)前第2頁；編輯于星期日\12點6分TheHardwareSourcesOpticsFilters&TargetsDetectors本文檔共66頁；當(dāng)前第3頁；編輯于星期日\12點6分SourcesEndWindowX-RayTubesSideWindowX-RayTubesRadioisotopesOtherSourcesScanningElectronMicroscopesSynchrotronsPositronandotherparticlebeams 本文檔共66頁；當(dāng)前第4頁；編輯于星期日\12點6分EndWindowX-RayTubeX-rayTubesVoltagedetermineswhichelementscanbeexcited.Morepower=lowerdetectionlimitsAnodeselectiondeterminesoptimalsourceexcitation(applicationspecific).本文檔共66頁；當(dāng)前第5頁；編輯于星期日\12點6分SideWindowX-RayTubeBeWindowSiliconeInsulationGlassEnvelopeFilamentElectronbeamTarget(Ti,Ag,Rh,etc.)CopperAnodeHVLead本文檔共66頁；當(dāng)前第6頁；編輯于星期日\12點6分RadioisotopesIsotopeFe-55Cm-244Cd-109Am-241Co-57Energy(keV)5.914.3,18.322,8859.5122Elements(K-lines)Al–VTi-BrFe-MoRu-ErBa-UElements(L-lines)Br-II-PbYb-PuNonenoneWhileisotopeshavefallenoutoffavortheyarestillusefulformanygaugingapplications.本文檔共66頁；當(dāng)前第7頁；編輯于星期日\12點6分OtherSourcesSeveralotherradiationsourcesarecapableofexcitingmaterialtoproducex-rayfluorescencesuitableformaterialanalysis.ScanningElectronMicroscopes(SEM)–Electronbeamsexcitethesampleandproducex-rays.ManySEM’sareequippedwithanEDXdetectorforperformingelementalanalysisSynchotrons-ThesebrightlightsourcesaresuitableforresearchandverysophisticatedXRFanalysis.

PositronsandotherParticleBeams–Allhighenergyparticlesbeamsionizematerialssuchthattheygiveoffx-rays.PIXEisthemostcommonparticlebeamtechniqueafterSEM.本文檔共66頁；當(dāng)前第8頁；編輯于星期日\12點6分SourceModifiersSeveralDevicesareusedtomodifytheshapeorintensityofthesourcespectrumorthebeamshapeSourceFiltersSecondaryTargetsPolarizingTargetsCollimatorsFocusingOptics本文檔共66頁；當(dāng)前第9頁；編輯于星期日\12點6分SourceFiltersFiltersperformoneoftwofunctionsBackgroundReductionImprovedFluorescenceDetectorX-RaySourceSourceFilter本文檔共66頁；當(dāng)前第10頁；編輯于星期日\12點6分FilterTransmissionCurve%TRANSMITTEDENERGYLowenergyx-raysareabsorbedAbsorptionEdgeX-raysabovetheabsorptionedgeenergyareabsorbedVeryhighenergyx-raysaretransmittedTiCrTitaniumFiltertransmissioncurveThetransmissioncurveshowsthepartsofthesourcespectrumaretransmittedandthosethatareabsorbed本文檔共66頁；當(dāng)前第11頁；編輯于星期日\12點6分FilterFluorescenceMethodENERGY(keV)TargetpeakWithZnSourcefilterFeRegionContinuumRadiationThefilterfluorescencemethoddecreasesthebackgroundandimprovesthefluorescenceyieldwithoutrequiringhugeamountsofextrapower.本文檔共66頁；當(dāng)前第12頁；編輯于星期日\12點6分FilterAbsorptionMethodENERGY(keV)TargetpeakWithTiSourcefilterFeRegionContinuumRadiationThefilterabsorptionMethoddecreasesthebackgroundwhilemaintainingsimilarexcitationefficiency.本文檔共66頁；當(dāng)前第13頁；編輯于星期日\12點6分SecondaryTargetsImprovedFluorescenceandlowerbackground

Thecharacteristicfluorescenceofthecustomlinesourceisusedtoexcitethesample,withthelowestpossiblebackground

intensity.Itrequiresalmost100xthefluxoffiltermethodsbutgivessuperiorresults.本文檔共66頁；當(dāng)前第14頁；編輯于星期日\12點6分SecondaryTargetsSampleX-RayTubeDetectorSecondaryTargetThex-raytubeexcitesthesecondarytargetTheSecondarytargetfluorescesandexcitesthesampleThedetectordetectsx-raysfromthesample本文檔共66頁；當(dāng)前第15頁；編輯于星期日\12點6分SecondaryTargetMethodENERGY(keV)TubeTargetpeakWithZnSecondaryTargetFeRegionContinuumRadiationSecondaryTargetsproduceamoremonochromaticsourcepeakwithlowerbackgroundthanwithfilters本文檔共66頁；當(dāng)前第16頁；編輯于星期日\12點6分SecondaryTargetVsFilterComparisonofoptimizeddirect-filteredexcitationwithsecondarytargetexcitationforminorelementsinNi-200本文檔共66頁；當(dāng)前第17頁；編輯于星期日\12點6分PolarizingTargetTheoryX-rayarepartiallypolarizedwhenevertheyscatteroffasurfaceIfthesampleandpolarizerareorientedperpendiculartoeachotherandthex-raytubeisnotperpendiculartothetarget,x-raysfromthetubewillnotreachthedetector.TherearethreetypeofPolarizationTargets:BarklaScatteringTargets-Theyscatterallsourceenergiestoreducebackgroundatthedetector.SecondaryTargets-Theyfluorescewhilescatteringthesourcex-raysandperformsimilarlytoothersecondarytargets.DiffractiveTargets-Theyaredesignedtoscatterspecificenergiesmoreefficientlyinordertoproduceastrongerpeakatthatenergy.本文檔共66頁；當(dāng)前第18頁；編輯于星期日\12點6分CollimatorsCollimatorsareusuallycircularoraslitandrestrictthesizeorshapeofthesourcebeamforexcitingsmallareasineitherEDXRForuXRFinstruments.TheymayrelyoninternalBraggreflectionforimprovedefficiency.SampleTubeCollimatorsizesrangefrom12micronstoseveralmm本文檔共66頁；當(dāng)前第19頁；編輯于星期日\12點6分FocusingOpticsBecausesimplecollimationblocksunwantedx-raysitisahighlyinefficientmethod.FocusingopticslikepolycapillarydevicesandotherKumakhovlensdevicesweredevelopedsothatthebeamcouldberedirectedandfocusedonasmallspot.Lessthan75umspotsizesareregularlyachieved.SourceDetectorBraggreflectioninsideaCapillary本文檔共66頁；當(dāng)前第20頁；編輯于星期日\12點6分DetectorsSi(Li)PINDiodeSiliconDriftDetectorsProportionalCountersScintillationDetectors本文檔共66頁；當(dāng)前第21頁；編輯于星期日\12點6分DetectorPrinciplesAdetectoriscomposedofanon-conductingorsemi-conductingmaterialbetweentwochargedelectrodes.X-rayradiationionizesthedetectormaterialcausingittobecomeconductive,momentarily.Thenewlyfreedelectronsareacceleratedtowardthedetectoranodetoproduceanoutputpulse.Inionizedsemiconductorproduceselectron-holepairs,thenumberofpairsproducedisproportionaltotheX-rayphotonenergy本文檔共66頁；當(dāng)前第22頁；編輯于星期日\12點6分Si(Li)DetectorWindowSi(Li)crystalDewarfilledwithLN2Super-CooledCryostatCooling:LN2orPeltierWindow:BerylliumorPolymerCountsRates:3,000–50,000cpsResolution:120-170eVatMnK-alphaFETPre-Amplifier本文檔共66頁；當(dāng)前第23頁；編輯于星期日\12點6分Si(Li)CrossSection本文檔共66頁；當(dāng)前第24頁；編輯于星期日\12點6分PINDiodeDetectorCooling:Thermoelectricallycooled(Peltier)Window:BerylliumCountRates:3,000–20,000cpsResolution:170-240eVatMnk-alpha本文檔共66頁；當(dāng)前第25頁；編輯于星期日\12點6分SiliconDriftDetector-SDD

Packaging:SimilartoPINDetector

Cooling:PeltierCountRates;10,000–300,000cps

Resolution:140-180eVatMnK-alpha本文檔共66頁；當(dāng)前第26頁；編輯于星期日\12點6分ProportionalCounterAnodeFilamentFillGases:Neon,Argon,Xenon,KryptonPressure:0.5-2ATMWindows:BeorPolymerSealedorGasFlowVersionsCountRatesEDX:10,000-40,000cpsWDX:1,000,000+Resolution:500-1000+eVWindow本文檔共66頁；當(dāng)前第27頁；編輯于星期日\12點6分ScintillationDetectorPMT(Photo-multipliertube)SodiumIodideDiskElectronicsConnectorWindow:BeorAlCountRates:10,000to1,000,000+cpsResolution:>1000eV本文檔共66頁；當(dāng)前第28頁；編輯于星期日\12點6分SpectralComparison-AuSi(Li)Detector10vs.14KaratSiPINDiodeDetector10vs.14Karat本文檔共66頁；當(dāng)前第29頁；編輯于星期日\12點6分PolymerDetectorWindowsOptionalthinpolymerwindowscompared toastandardberylliumwindowsAffords10ximprovementintheMDLforsodium(Na)本文檔共66頁；當(dāng)前第30頁；編輯于星期日\12點6分DetectorFiltersFiltersarepositionedbetweenthesampleanddetectorinsomeEDXRFandNDXRFsystemstofilteroutunwantedx-raypeaks.SampleDetectorX-RaySourceDetectorFilter本文檔共66頁；當(dāng)前第31頁；編輯于星期日\12點6分DetectorFilterTransmission%TRANSMITTEDENERGYLowenergyx-raysareabsorbedEOIistransmittedAbsorptionEdgeX-raysabovetheabsorptionedgeenergyareabsorbedVeryhighenergyx-raysaretransmittedSClAniobiumfilterabsorbsClandotherhigherenergysourcex-rayswhilelettingSx-rayspass.Adetectorfiltercansignificantlyimprovedetectionlimits.NiobiumFilterTransmissionandAbsorption本文檔共66頁；當(dāng)前第32頁；編輯于星期日\12點6分FilterVs.NoFilterUnfilteredTubetarget,Cl,andArInterferencePeakDetectorfilterscandramaticallyimprovetheelementofinterestintensity,whiledecreasingthebackground,butrequires4-10timesmoresourceflux.Theyarebestusedwithlargeareadetectorsthatnormallydonotrequiremuchpower.本文檔共66頁；當(dāng)前第33頁；編輯于星期日\12點6分RossVs.HullFiltersThepreviousslidewasanexampleoftheHullorsimplefiltermethod.TheRossmethodillustratedhereforClanalysisusesintensitiesthroughtwofilters,onetransmitting,oneabsorbing,andthedifferenceiscorrelatedtoconcentration.ThisisanNDXRFmethodsincedetectorresolutionisnotimportant.本文檔共66頁；當(dāng)前第34頁；編輯于星期日\12點6分WavelengthDispersiveXRFWavelengthDispersiveXRFreliesonadiffractivedevicesuchascrystalormultilayertoisolateapeak,sincethediffractedwavelengthismuchmoreintensethanotherwavelengthsthatscatterofthedevice.

SampleDetectorX-RaySourceDiffractionDeviceCollimators本文檔共66頁；當(dāng)前第35頁；編輯于星期日\12點6分DiffractionThetwomostcommondiffractiondevicesusedinWDXinstrumentsarethecrystalandmultilayer.Bothworkaccordingtothefollowingformula.nl=2d′sinqn=integerd=crystallatticeormultilayerspacingq=Theincidentangle=wavelengthAtoms本文檔共66頁；當(dāng)前第36頁；編輯于星期日\12點6分MultilayersWhilethecrystalspacingisbasedonthenaturalatomicspacingatagivenorientationthemultilayerusesaseriesofthinfilmlayersofdissimilarelementstodothesamething.Modernmultilayersaremoreefficientthancrystalsandcanbeoptimizedforspecificelements.OftenusedforlowZelements.本文檔共66頁；當(dāng)前第37頁；編輯于星期日\12點6分SollerCollimatorsSollerandsimilartypesofcollimatorsareusedtopreventbeamdivergence.TheareusedinWDXRFtorestricttheanglesthatareallowedtostrikethediffractiondevice,thusimprovingtheeffectiveresolution.SampleCrystal本文檔共66頁；當(dāng)前第38頁；編輯于星期日\12點6分CoolingandTemperatureControlThediffractiontechniqueisrelativelyinefficientandWDXdetectorscanoperateatmuchhighercountrates,soWDXInstrumentsaretypicallyoperatedatmuchhigherpowerthandirectexcitationEDXRFsystems.Diffractiondevicesarealsotemperaturesensitive.

ManyWDXRFInstrumentsuse:X-RayTubeCoolers,andThermostaticallycontrolledinstrumentcoolers本文檔共66頁；當(dāng)前第39頁；編輯于星期日\12點6分ChamberAtmosphereSampleandhardwarechambersofanyXRFinstrumentmaybefilledwithair,butbecauseairabsorbslowenergyx-raysfromelementsparticularlybelowCa,Z=20,andArgonsometimesinterfereswithmeasurementspurgesareoftenused.Thetwomostcommonpurgemethodsare: Vacuum-Forusewithsolidsorpressedpellets Helium-Forusewithliquidsorpowderedmaterials本文檔共66頁；當(dāng)前第40頁；編輯于星期日\12點6分ChangersandSpinnersOthercommonlyavailablesamplehandlingfeaturesaresamplechangersorspinners.AutomaticsamplechangersareusuallyofthecircularorXYZstagevarietyandmayhavehold6to100+samplesSampleSpinnersareusedtoaverageoutsurfacefeaturesandparticlesizeaffectspossiblyoveralargertotalsurfacearea.

本文檔共66頁；當(dāng)前第41頁；編輯于星期日\12點6分TypicalPINDetectorInstrumentThisconfigurationismostcommonlyusedinhigherendbenchtopEDXRFInstruments.本文檔共66頁；當(dāng)前第42頁；編輯于星期日\12點6分TypicalSi(Li)DetectorInstrumentThishasbeenhistoricallythemostcommonlaboratorygradeEDXRFconfiguration.本文檔共66頁；當(dāng)前第43頁；編輯于星期日\12點6分EnergyDispersiveElectronicsFluorescencegeneratesacurrentinthedetector.InadetectorintendedforenergydispersiveXRF,theheightofthepulseproducedisproportionaltotheenergyoftherespectiveincomingX-ray.DETECTORSignaltoElectronicsElementAElementCElementBElementD本文檔共66頁；當(dāng)前第44頁；編輯于星期日\12點6分Multi-ChannelAnalyserDetectorcurrentpulsesaretranslatedintocounts(countspersecond,“CPS”).PulsesaresegregatedintochannelsaccordingtoenergyviatheMCA(Multi-ChannelAnalyser).SignalfromDetectorChannels,EnergyIntensity(#ofCPSperChannel)本文檔共66頁；當(dāng)前第45頁；編輯于星期日\12點6分WDXRFPulseProcessingTheWDXmethodusesthediffractiondeviceandcollimatorstoobtaingoodresolution,soThedetectordoesnotneedtobecapableofenergydiscrimination.Thissimplifiesthepulseprocessing.Italsomeansthatspectralprocessingissimplifiedsinceintensitysubtractionisfundamentallyanexerciseinbackgroundsubtraction.Note:Someenergydiscriminationisusefulsinceitallowsforrejectionoflowenergynoiseandpulsesfromunwantedhigherenergyx-rays.

本文檔共66頁；當(dāng)前第46頁；編輯于星期日\12點6分EvaluatingSpectraK&LSpectralPeaksRayleighScatterPeaksComptonScatterPeaksEscapePeaksSumPeaksBremstrahlungInadditiontoelementalpeaks,otherpeaksappearinthespectra:本文檔共66頁；當(dāng)前第47頁；編輯于星期日\12點6分K&LSpectralLinesK-alphalines:

Lshelle-transitiontofillvacancyinKshell.Mostfrequenttransition,hencemostintensepeak.

K-betalines:

Mshelle-transitionstofillvacancyinKshell.LShellKShell

L-alphalines:

Mshelle-transitiontofillvacancyinLshell.

L-betalines:

Nshelle-transitiontofillvacancyinLshell.KalphaKbetaMShellLalphaNShellLbeta本文檔共66頁；當(dāng)前第48頁；編輯于星期日\12點6分K&LSpectralPeaksRhX-rayTubeL-linesK-Lines本文檔共66頁；當(dāng)前第49頁；編輯于星期日\12點6分ScatterSomeofthesourceX-raysstrikethesampleandarescatteredbackatthedetector.

Sometimescalled “backscatter”SampleSourceDetector本文檔共66頁；當(dāng)前第50頁；編輯于星期日\12點6分RayleighScatterX-raysfromtheX-raytubeortargetstrikeatomwithoutpromotingfluorescence.Energyisnotlostincollision.(EI=EO)Theyappearasasourcepeakinspectra.AKA-“Elastic”ScatterEIEORhX-rayTube本文檔共66頁；當(dāng)前第51頁；編輯于星期日\12點6分ComptonScatterX-raysfromtheX-raytubeortargetstrikeatomwithoutpromotingfluorescence.Energyislostincollision.(EI>EO)Comptonscatterappearsasasourcepeakinspectra,slightlylessinenergythanRayleighScatter.AKA-“Inelastic”ScatterEIEORhX-rayTube本文檔共66頁；當(dāng)前第52頁；編輯于星期日\12點6分SumPeaks2photonsstrikethedetectoratthesametime.Thefluorescenceiscapturedbythedetector,recognizedas1photontwiceitsnormalenergy.Apeakappearsinspectra,at:2X(ElementkeV).本文檔共66頁；當(dāng)前第53頁；編輯于星期日\12點6分EscapePeaksX-raysstrikethesampleandpromoteelementalfluorescence.SomeSifluorescenceatthesurfaceofthedetectorescapes,andisnotcollectedbythedetector.Theresultisapeakthatappearsinspectrum,at:ElementkeV-SikeV(1.74keV).RhX-rayTube1.74keV本文檔共66頁；當(dāng)前第54頁；編輯于星期日\12點6分BrehmstrahlungBrehmstrahlung(orContinuum)Radiation:

Germanfor“breakingradiation”,noisethatappearsinthespectraduetodecelerationofelectronsastheystriketheanodeoftheX-raytube.本文檔共66頁；當(dāng)前第55頁；編輯于星期日\12點6分InterferencesSpectralInterferencesEnvironmentalInterferencesMatrixInterferences本文檔共66頁；當(dāng)前第56頁；編輯于星期日\12點6分SpectralInterferencesSpectralinterferencesarepeaksinthespectrumthatoverlapthespectralpeak(regionofinterest)oftheelementtobeanalyzed.Examples:K&LlineOverlap-S&Mo,Cl&Rh,As&PbAdjacentElementOverlap-Al&Si,S&Cl,K&Ca...Resolutionofdetectordeterminesextentofoverlap.220eVResolution140eV

ResolutionAdjacentElementOverlap本文檔共66頁；當(dāng)前第57頁；編輯于星期日\12點6分EnvironmentalInterferencesLightelements(Na-Cl)emitweakX-rays,easilyattenuatedbyair.Solution:PurgeinstrumentwithHe(lessdensethanair=lessattenuation).Evacuateairfromanalysischamberviaavacuumpump.EitherofthesesolutionsalsoeliminateinterferencefromAr(spectraloverlaptoCl).Argon(Ar)isacomponentofair.AirEnvironmentHeEnvironmentAlAnalyzedwithSiTarget本文檔共66頁；當(dāng)前第58頁；編輯于星期日\12點6分MatrixInterferencesAbsorption:

Anyelementcanabsorborscatterthefluorescenceoftheelementofinterest.Enhancement:

Characteristicx-raysofoneelementexciteanotherelementinthesample,enhancingitssignal.InfluenceCoefficients,sometimescalledalphacorrectionsareusedtomathematicallycorrectforMatrixInterferencesAbsorption/EnhancementEffects本文檔共66頁；當(dāng)前第59頁；編輯于星期日\12點6分Absorption-EnhancementAffectsIncomingsourceX-rayfluorescesFe.FefluorescenceissufficientinenergytofluoresceCa.Caisdetected,Feisnot.Responseisproportionaltoconcentrationsofeachelement.Red

=Fe,absorbedBlue

=Ca,enhancedSource

X-rayX-RayCapturedbythedetector.Sample本文檔共66頁；當(dāng)前第60頁；編輯于星期日\12點6分SoftwareQualitativeAnalysisSemi-QuantitativeAnalysis(SLFP,NBS-GSC.)QuantitativeAnalysis(MultipleintensityExtractionandRegressionmethods)本文檔共66頁；當(dāng)前第61頁；編輯于星期日\12點6分QualitativeScanPeakIDThisspectrumalsocontraststheresolutionofaPINdiodedetectorwithaproportionalcountertoillustratetheimportanceofdetectorresolutionwithregardtoqualitativeanalysis.AutomatedPeakidentificationprogramsareausefulqualitativeexaminationtool

ElementTags本文檔共66頁；當(dāng)前第62頁；編輯于星期日\12點6分Semi-QuantitativeAnalysisThealgorithmcomputesboththeintensitytoconcentrationrelationshipandtheabsorptionaffectsResultsaretypicallywithin10-20%ofactualvalues.SLFPStandardlessFundamentalParametersFP(withStandards)NBS-GSC,NRLXRF,Uni-Quant