红外ATR-FTIR

AttenuatedTotalReflectionFlouriertransformedInfraredSpectroscopyATR-FTIRcatalogueBriefintroductionofATRHowATRworksapplicationsconclusionsBriefintroductionofATRAttenuatedTotalReflectance(ATR)isanIRsamplingtechnique.Itmeasuresthechangesinaninfraredbeamwithtotallyinternalreflectionwhenitcomesintocontactwithasample.ATRisusedforsurfaceanalysisofsolidsandliquids.ATRgenerallyallowsqualitativeorquantitativeanalysisofsampleswithlittleornosamplepreparationwhichgreatlyspeedssampleanalysis.HowATRWorksWithATRsamplingwedirecttheIRbeamintoacrystalofrelativelyhigherrefractiveindexatacertainangle.TheIRbeamreflectsfromtheinternalsurfaceofthecrystalandcreatesanevanescentwave.Itextendsbeyondthesurfaceofthecrystalintothesampleheldincontactwiththecrystal.wheren2istherefractiveindexofthesample,n1istherefractiveindexofthecrystalandθcisthecriticalangle.1whenexceedingthecriticalangle,wewillgetatotallyreflectionoftheIRbeam.2n1n2,thecrystalhasarelativelyhighrefractiveindex.LightpathintheATRsetupThesampleisputontopofthebluecrystal.TheIRbeampicksupasignalasitpassesafewmicronintothesampleandcreatesanevanescentwave.Whiletheevanescentwaveextendsonly0.5-5µmbeyondthecrystalsurfaceandintothesample.schematicillustrationEquipmenttopushthesampleontothecrystalThiscanbeachievedbypressingthesampledownonthecrystal.Ifthesubstanceunderstudyisaliquid,itissimplydroppedontothecrystal,therebyobtainingoptimalcontact.Thereforeitisimportanttoobtaingoodcontactbetweenthecrystalandthesample.TinfoilTraditionalIRspectroscopyneedpreparationofthesample.schematicillustrationFirstacoupleofmilligramofsampleismixedwithabout200mgofKBrpowder.Thenthemixtureispressedintoatabletwhichisthenusedintheanalysis.TraditionalIRdoesnotworkquiteeffectively,andforanalyzingsurfacelayerstructure.ATR-FTIRhasbecomeakindofbeneficialtoolandmeansforanalyzingsamplesandsurfaceproperties.ATR-FTIRhasbeenappliedtoeveryrealmsuchasspinningandweaving,qualitytesting,publicsecurityandsoon.applicationsCharacterizationofSurfaceTreatmentsofCorkStoppersbyFTIR-ATRJ.Agric.FoodChem.2006,54,4932-4936Thepaperproposedananalyticalmethodforidentificationofthepresenceofsurfacetreatmentsincorkstoppers.Bands1258,1079,1010and787cm-1arespecificofsilicone.Bands2963,2916,and2850cm-1,whicharelessspecific,correspondingtoC-Hbonds,hadintensitiesthatdifferedgreatlyinbothtypesofcompoundsThe2963cm-1bandisduetoCH3andoccursinsiliconesexclusivelyastheonlyalkane.Thesespectraexhibitbandscorrespondingtothecorkmatrix.Themostintenseoccurringat1735cm-1,duetocarbonylbonds,mainlyfromsuberin,andbandsat1010-1300cm-1,duemainlytocarbohydrateandligninC-O.Thelattercanoverlapwiththoseofsilicone.Bydeterminationoftheabsorbanceattheselectedbands,itwaspossibletodifferentiatethetypeoftreatmentappliedtoagivenstopper.Itconcludesthatthecharacteristicsoftheproposedmethod(ATR-FTIR)makeitcertainlyapplicableinindustrysettings.Anal.Chem.2010,82,3139–3145insitustudiesonelectrochemicallyinducedprocessesatIRwaveguidesurfacesviaevanescentfieldabsorptionspectroscopyschemeoftheSECM-ATR-FTIRsetuptheATRcrystalhasbeenbuiltintoanelectrochemicalcellasthecentralpartofthebaseplateTheα-Hpeakareaswereintegratedfrom670to710cm-1.thepolymerizationlevelsfordifferentreactiontimeswerecalculatedbydeterminingthepercentageofpeakareachangeItisbetweentheintegratedα-HpeakareaofpolymerizedSNSatthedifferentpolymerizationtimesandtheintegratedα-HareaoftheSNSmonomer.Presentthefirstinstrumentalcombinationofscanningelectrochemicalmicroscopy(SECM)withinsituattenuatedtotalreflectioninfraredspectroscopy(IR-ATR)usingasinglebounceATRcrystalasSECMsubstrate.ThelevelofpolymerizationcouldbeevaluatedbytherecordedIRspectra.WhileusingATRtechnique,weonlyneedlittleornopreparationofsamples.UsingATRtocharacterizethesurfacepropertiesisofmostinterestnowadays.Wecanalsomonitorinsitureactions.ATR-FTIRcanmostlyspeedtheanalysisofsamples.conclusionsTheend.Thankyou!