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1、ARTICLEpubs.acs.org/JACSDramaticReductionofIRVibrationalCrossSectionsofMoleculesEncapsulatedinCarbonNanotubes†,‡,^§,^,
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3、,§,†DmitryV.Kazachkin,YoshifumiNishimura,HenrykA.Witek,*StephanIrle,*andEricBorguet*†DepartmentofChemistry,TempleUniversity,Philadelphia,Penns
4、ylvania19122,UnitedStates‡DepartmentofChemicalEngineering,UniversityofPittsburgh,Pittsburgh,Pennsylvania15261,UnitedStates§InstituteforAdvancedResearchandDepartmentofChemistry,NagoyaUniversity,Nagoya464-8602,Japan)DepartmentofAppliedChemistryandInstituteofMolecu
5、larScience,NationalChiaoTungUniversity,Hsinchu30010,TaiwanbSSupportingInformationABSTRACT:Combinedtemperature-programmeddesorptionandIRstudiessuggestthatabsorptioncrosssectionsofIR-activevibrationsofmolecules“strongly”boundtosingle-wallcarbonnanotubes(SWCNTs)are
6、reducedatleastbyafactorof10.QuantumchemicalsimulationsshowthatIRintensitiesofendohedrallyencapsulatedmoleculesaredramaticallyreduced,andidentifydielectricscreeningbyhighlypolarizableSWCNTsidewallsastheoriginofsuch“screening”.Theobservedintensityreductionoriginat
7、esfromasizablecancellationofadsorbatedipolemomentsbymirrorchargesdynamicallyinducedonthenanotubesidewalls.Forexohedrallyadsorbedmolecules,thedielectricscreeningisfoundtobeorientation-dependentwithasmallermagnitudeforadsorptioningrooveandinterstitialsites.Thepres
8、entedresultsclearlydemonstrateandquantifythescreeningeffectofSWCNTsandunequivocallyshowthatIRspectroscopycannotbeappliedinastraightforwardmannertothestudyofpeapodsystems.’INTRODUCTIONinsidethefullereneC60waspredictedtobereducedroughly203-fold.Setyowatietal.explai
9、nedthereductionofIRvibrationalCarbonnanotubes(CNTs)areideallysuitedfortheencap-17intensitiesofsomevibrationalmodesofmacromoleculesad-sulationofchemicalspecies,withmanypossibleapplications.30sorbedontheoutsideofCNTsidewallsbytheappearanceofItisthereforeclearthat
10、effectiveexperimentaltoolsarerequiredimagedipolesinanalogywithIRsignalreductionofmoleculesforthecharacterizationoftheencapsulatedspecies.Transmis-315,810adsorbedonmet
