Fit2D简明教程

Fit2Dtutorial-1-Batchconversionfrom2Dto1DpowderdiffractiondatausingFit2D1V12.043Ashorttutorial1Copyright1987-2004AndyHammersley/ESRFFit2Dtutorial-2-1.IntroductionInsitupowderdiffractiondataareoftenrecordedusing2-dimensionaldetectorslikeimageplates(likethewidespreadMar345detector)orCCD-cameras.Dependingonthenatureoftheexperimentandthereadouttimesofthedetector,hundredsorthousandsof2D-powderpatternsaregeneratedduringsuchanexperiment.InordertoprocessthepowderdiffractiondatawithsoftwarelikePowder3D(Hinrichsen,Dinnebier&Jansen,2004),theseriesoftwodimensionalpowderdiffractiondatamustbeconvertedintoseriesofonedimensionalpowderpatterns(2θversusintensity).AsuitablesoftwareforthispurposeisthewellknownprogramFit2DfromAndyHammerley(Hammersley,A.P.;Svensson,S.O.;Hanfland,M.;Fitch,A.N.;Hausermann,D.HighPressureResearch1996,14,235-248).Thesoftwareisavailablefreeofchargeatθscans.Theaimofthissimpletutorialistoguidetheunexperienceduserthroughthisfirststepofdatareductionstep-by-step.2.DetectorcalibrationBeforethestartofanynewexperiment,itisgoodpracticetomeasureastandardmateriallikelanthanumhexaborideforcalibrationofwavelength,sample-to-detectordistanceandtiltangle.2.1DatainputAfterstartingtheFit2Dprogram,thescreentotherightappears.TheconditionsofuseshouldbeacceptedbypressingtheIACCEPTbuttonFit2Dtutorial-3-Now,thedimensionsofthepixelarraysmustbeset.FortheMar345,theX-andY-dimensionareeither2300or3450pixels.Theextensionofthefilenameoftencontainsthisinformation.ConfirmtheinformationbyclickingO.K..ThemainmenuappearsinwhichPOWDERDIFFRACTION(2-D)shouldbeselected.Fit2Dtutorial-4-Inthepowderdiffractionsubmenu,the2D-powderpatternofthemeasuredstandardmaterialmustbereadinusingtheINPUTbutton.Thefollowingmenuallowsforselectionofthefilecontainingthe2D-powderpatternofthemeasuredstandardmaterial.Inourcase,thefilenameislab6_170_922_001.mar2300containingthemeasurementofalanthanumhexaboridecapillarywithaMar345detectorof2300x2300pixelsresolution.Fit2Dtutorial-5-Soonafterreadingthefile,amenuwithcontrolofthedetectordistortioncorrectionsoccurs.Incaseofmodernself-calibratingdetectorsliketheMar345,noexternaldarkcurrent,flatfieldorspatialdistortioncorrectionsmustbeapplied.ThemenuisconfirmedbypressingtheO.K.button.Now,the2D-powderpatternofthereferencematerialisdisplayed.Itusuallymakessensetoselectinversescalingandscalingtoweakpeaksasdisplayoptions.Fit2Dtutorial-6-Tochangethecolorandscaling,clickOPTIONS,followedbyCOLOURS.Now,pressINVERSE-GREY-SCALEandthenEXIT.Fit2Dtutorial-7-AfterpressingtheZ-SCALINGbutton,theintensityscalingmenuappearsinwhichtheWEAKPEAKSbuttonispressed.Dependingontheintensityofthebackgroundandtheoverallintensityofthepattern,otherscalingoptionsmightbeappropriate.Toleavethemenu,presstheEXITbutton.Thenext(important)stepdealswiththemaskingofunwantedscatteringinformationwhichshouldnotbeusedfortheintegrationofthepowderpatternlikeKossel-lines,diffractionbysinglegrains,beamstopetc.Tomaskouttheshadowoftheprimarybeamstop,theregionofinterestmustfirstbezoomedinusingtheZOOMINbutton.Fit2Dtutorial-8-Now,aftersufficientdetailsarevisible,theMASKPOLYGONshouldbepressed.IfONECLICKmodeisactive(checkbottomrightbutton),thepolygonpointscanbesetdirectly,inTWOCLICKmode,anadditionalconfirmationand/orcorrectioninaspyglasswindowisnecessary.Thetwodifferentmodishouldbeselectedaccordingtorequiredaccuracy.Fit2Dtutorial-9-Thefinalresultofamaskedprimarybeamstopshouldlookmoreorlesslikethepicturetotheleft.Itmightbenecessarytomaskoutadditionalpartsofthe2Dpowderpatternusingothermenuoptions.BeforeleavingthemaskingmenubypressingtheEXITbutton,makesurethattheFULL-UN-ZOOMbuttonhasbeenpressed,otherwise,theintegrationwillonlybeperformedonthe2D-datavisibleintheactualwindow.Ifyouseethefull2D-patternwiththeselectedmask,presstheCALIBRANTbutton.Inthecalibrationmenuselectthereferencematerialused(LANTHANUMHEXABORIDEinourcase).Fit2Dtutorial-10-Fillintheapproximatevaluesofthewavelengthandthesample–to-detectordistance.Therefinementflagsforthesample-to-detectordistance,thewavelength,thenon-orthogonality,andtheX/Y-beamcentreareusuallyswitchedon.AfterpressingtheOKbutton,theprogramasksforatleastthreecoordinatesoftheinnerringofthereferencematerial.Todefinetheinnerring,TWOCLICKmodeshouldbeactiveandsome10pointsequallydistributedovertheinnerringshouldbeselectedtoensureproperstatistics.Fit2Dtutorial-11-Afterconfirmationofthelastpoint,theprogramautomaticallysearchesforallringsofthestandardmaterial.Now,itistimetoperformtheintegrationofthe2D-powderdataofthereferencematerialtocheckthecorrectnessofthepreviousactions.PresstheINTEGRATEbutton.Thefirstoftwoparameterwindowscontainsallimportantparametersnecessaryforthisandthefollowingintegrations.Thisisagoodmomenttocheckforunrealisticparameters.IftheFit2Dprogramisexitedregularly,itwillk