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1、JOURNALOFAPPLIEDPHYSICSVOLUME88,NUMBER51SEPTEMBER2000Fibersofalignedsingle-walledcarbonnanotubes:PolarizedRamanspectroscopya)b)c)H.H.Gommans,J.W.Alldredge,H.Tashiro,J.Park,J.Magnuson,d)andA.G.RinzlerDepartmentofPhysics,UniversityofFlorida,Gainesville,Florida32611~Received14March2000;accepte
2、dforpublication19May2000!Toprobetheone-dimensionalnatureofsingle-wallcarbonnanotubes~SWNTs!inbulksamples,wehavedevisedasimplemethodforgenerating®bersofalignedSWNTs.Wemeasuredpolarization-dependentRamanspectraontheoriented®bers.Contrarytowhatisexpectedfromtheirtheoreticallyassignedvibration-
3、modesymmetries,alltheRamanlineintensitiesareobservedtodecreaseinnearlyequalamountsforthe647.1nmlaserexcitationpolarizedperpendiculartothe®beraxisversusthatpolarizedparalleltothe®beraxis.TheeffectisexplainedasalossofresonanceRamanscatteringfortheperpendicularpolarizationcase.©2000AmericanIns
4、tituteofPhysics.@S0021-8979~00!00517-X#I.INTRODUCTIONtionofthesymmetryspeciesofthevibrationalmoderespon-siblefortheline.BecauseorientednanotubesampleshaveLow-dimensionalsystemsprovideafruitfulareaofre-notpreviouslybeenavailable,allassignmentshavebeensearchbothforthepropertiesthatcanarisefro
5、mthereducedbasedstrictlyonmodeling.Aswedescribebelow,the1Ddimensionandforelucidationofemergentpropertiesinthreecharacterofthenanotubescomplicatestheapplicationofpo-dimensions.Single-walledcarbonnanotubes~SWNTs!,withlarizedRamanmeasurementsformakingsuchmodeassign-theirwell-de®nedatomicstruct
6、ure,chemicalstability,smallments.diameters,andhighaspectratios,constitutewonderfulone-dimensional~1D!moleculesforinvestigating1Deffects.AnimportantrecentexampleisprovidedbythesharpVanHoveII.EXPERIMENTALDETAILSsingularitiesobservedintunnelingspectroscopymeasure-ThealignedSWNT®berswereassembl
7、edfromhighly1,2mentsonindividualnanotubes.puri®ed,7laser-vaporization-grown3SWNTsdispersedbyul-Inpresenthigh-yieldmethodsofsynthesis,thenano-trasonicationinN,N-dimethylformamide~DMF!.SWNTtubesself-assembleintowell-orderedbundlesofafewtoconcentrationsof;0
