Web Release Date: May 22,
Raman Spectral Evolution in Individual Metallic Single-Walled Carbon Nanotubes upon
Covalent Sidewall Functionalization
Department of Materials Science and Engineering and Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801
Received: January 22, 2007
In Final Form: March 25, 2007
Abstract:
Changes in the Raman spectra of individual metallic single-walled carbon nantoubes (SWNTs) upon sidewall covalent bond formation have been studied. In light of the Fermi level shift dependent G-band line shape and D-band intensity in metallic tubes, the validity of commonly used D to G intensity ratio as an assessment tool for covalent bond formation is first examined. The evolution of G-band and disorder Raman spectral features upon covalent reaction with 4-bromobenzene diazonium tetrafluoroborate is then presented. The initial degree of disorder has a strong influence on the covalent sidewall functionalization. Implications on developing electronically selective covalent chemistries and assessing their selectivity in separating metallic and semiconducting SWNTs are discussed.
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