Raman microspectroscopy of soot and related carbonaceous materials：Spectral analysis and structural information.docx

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1、Ramanmicrospectroscopyofsootandre1atedcarbonaceousmateria1s:Spectra1ana1ysisandstructura1informationA.Sadezkyaj,H.Muckenhuberb,H.Grotheb,R.Niessnera,U.Po,sch1i,InstituteofHydrochemistrj,Technica1UniversityofMunich.Marchioninistr.17,D-81377Munich,GermanybInstituteofMateria1sChemistry.ViennaUniversity

2、OfTechnoIogy.Veterinaerp1atzI/GA.A-12IOVienna.AustriaReceived6September2004;accepted10February2005Avai1ab1eon1ine23March2005AbstractExperimenta1conditionsandmathematica1uingproceduresfortheco11ectionandana1ysisofRamanspectraofsootandre1atedcarbonaceousmateria1shavebeeninvestigatedandoptimisedwithaRa

3、manmicroscopesystemoperatedatthreedifferent1aserexcitationwave1engths(514,633,and780ntn).Severa1bandcombinationsforspectra1ana1ysishavebeentested,andacombinationoffour1orentzian-Shapedbands(G,DI,D2,D4)atabout1580,1350,1620,and1200cm1,respective1y,withaGaussianshapedband(D3)at15(X)cm1wasbestsuitedfor

4、thefirst-orderspectra.Thesecond-orderspectrawerebestfittedwith1orentzian-Shapedbandsatabout2450,27(X),29(X),and31(X)cm1.Spectra1parameters(bandpositions,fu11widthsatha1fmaximum,andintensityratios)arereportedforsevera1typesofindustria1carbonb1ack(DegussaPrintex,CabotMonarch),diese1st(particu1atematte

5、rfrommodernheavydutyvehic1eandpassengercarengineexhaust.NISTSRM1650),spark-dischargesoot(Pa1asGfG1OO),andgraphite.Severa1parameters,inparticu1arthewidthoftheD1bandat1350cm1,providestructura1informationanda11owtodiscriminatethesamp1emateria1s,butthecharacterisationanddistinctionofdifferenttypesofSOO1

6、is1imitedbytheexperimenta1reproducibi1ityofthespectraand(hestatistica1uncertaintiesofcurvefitting.Theresu1tsarediscussedandcomparedwithX-raydiffractionmeasurementsandear1ierRamanspectroscopicstudiesofcomparab1emateria1s,wheredifferentmeasurementandfittingprocedureshadbeenapp1ied.2005E1sevier1td.A11r

7、ightsreserved.Keywords:Soot,Graphiticcarbon;Ramanspectroscopy:Microstructure1.IntroductionSootistechnica11ydefinedastheb1ackso1idproductofincomp1etecombustionorpyro1ysisoffossi1fue1sandotherorganicmateria1s.Itp1aysimportantro1esasanindustria1fi11erandpigmentontheonehand(carbonb1ack),andasatraffic-re

8、1atedairpo11utantontheotherhand(diese1soot).Soo1isprimari1ycomposedofcarbon(8()%)andconsistsofagg1omeratedPrimarypartic1eswithdiametersontheorderof10-30nmcomprisingcrysta11ineandamorphousdomains.Thegraphite-1ikecrysta11inedomainstypica11yconsistof3-4Iurbostra1ica11ystackedgraphene1ayers,withaverage1

9、atera1extensions(1a)ofupto3nmandinter1ayerdistancesofabout3.5A,andcanberegardedashigh1ydisorderedgraphitic1attices1,2.Inanidea1graphitic1atticethedistancebetweenpara11e1graphene1ayers(p1anarhexagona1structuresofsp2-hybridizedcarbonatomswithcova1entbond1engthsof1.42A)is3.35A,andthe1ayersarearrangedin

10、ana1ternatingsequenceABAB.ThisCorrespondingauthor.Te1.:49218078238；fax：4989218078255.correspondstoahexagona1c1osestcrysta1structurewithE-mai1address：u1rich.poesch1ch.ium.de(U.Posch1),Unitce11soffourCatomsattwotypesof1atticesiteswith1,11u.jf.r,1differentcoordination(twoornoneighbouringCatomsonNowat1a

11、boratoiredeCombustionetdeSystemesRcactifs,CNRS.F-45071reanspranceaperpendicu1araxisthroughtheadjacent-6223/$-seefrontmatter2005E1sevier1td.A11rig1sreserved.doi:10.10I6/j.cartxn.25.02.018para11e11ayers).Theamorphous(i.e.non-graphite-1ike)domainsarecomposedofpo1ycyc1icaromaticcompounds,whichcanberegar

12、dedasgraphene1ayerprecursorsinirregu1aroronion-1ikearrangements(fu11erenoidstructures),andotherorganicandinorganiccomponents(a1iphatics,su1fate,meta1oxides,etc.).Theactua1physica1andchemica1structureofsoot,itse1ementa1composition(carbon,hydrogen,oxygen,etc.),andtheratioofcrysta11inegraphite-1iketoam

13、orphousorganiccarbondependonthestartingmateria1sandconditionsofthecombustionorpyro1ysisprocess(fue1type,fue1/oxygenratio,f1ametemperature,residencetime,etc.2,3)Thegraphiticcarbonfractionofsootcanbeincreasedbyannea1ingproceduresathightemperatures2-51.Forthestructura1characterisationofhigh1yorderedso1

14、idmateria1s(crysta11ine1ong-rangeorder)diffractiontechniquesareusua11ythemethodsofchoice.Forhigh1ydisorderedmateria1ssuchassoot,however,Ramanspectroscopyismorepromising,becauseitissensitivenoton1ytocrysta1structuresbuta1sotomo1ecu1arstructures(short-rangeorder).TheRamansigna1sofgraphitecrysta1sresu1

15、tfrom1atticevibrationsandareverysensitivetothedegreeofstructura1disorder.Thespectrumofnear-idea1graphite,whichisobservedfor1argesing1egraphiticcrysta1sandhigh1yorientedpo1ycrysta11inegraphite(HOPG),significant1ydiffersfromtheRamanspectraofdisturbedgraphitic1attices,suchasregu1arpo1ycrysta11ineghiteo

16、rboron-dotedHOPG6-17(Tab1e1).Amongthesubstancesinvestigatedinear1ierstudiesaredifferenttypesofgraphite6,12,13,17-19,diamondfi1ms15,20,g1assycarbon18,19,21,amorphousandgraphiticcarbonfi1ms4,22,coa1,pitchandcoa1fibres18,activatedcarbon18,19,andfu11erenes23.RosenandNovakov24,25havefirstusedRamanspectroscopytoprovethepresenceofgraphite-1ikecarbonindiese1enginesoot,andtheirinvestigationshavebe