title: Spectroscopy of covalently functionalized graphene.
abstract: In order to engineer a band gap into graphene, covalent bond-forming reactions can be used to change the hybridization of the graphitic atoms from sp(2) to sp(3), thereby modifying the conjugation length of the delocalized carbon lattice; similar side-wall chemistry has been shown to introduce a band gap into metallic single-walled carbon nanotubes. Here we demonstrate that the application of such covalent bond-forming chemistry modifies the periodicity of the graphene network thereby introducing a band gap (∼0.4 eV), which is observable in the angle-resolved photoelectron spectroscopy of aryl-functionalized graphene. We further show that the chemically-induced changes can be detected by Raman spectroscopy; the in-plane vibrations of the conjugated π-bonds exhibit characteristic Raman spectra and we find that the changes in D, G, and 2D-bands as a result of chemical functionalization of the graphene basal plane are quite distinct from that due to localized, physical defects in sp(2)-conjugated carbon.
authors.affiliation: Center for Nanoscale Science and Engineering, University of California, Riverside, California 92521, USA.
authors.forename: Sandip
authors.initials: S
authors.lastname: Niyogi
authors.forename: Elena
authors.initials: E
authors.lastname: Bekyarova
authors.forename: Mikhail E
authors.initials: ME
authors.lastname: Itkis
authors.forename: Hang
authors.initials: H
authors.lastname: Zhang
authors.forename: Kristin
authors.initials: K
authors.lastname: Shepperd
authors.forename: Jeremy
authors.initials: J
authors.lastname: Hicks
authors.forename: Michael
authors.initials: M
authors.lastname: Sprinkle
authors.forename: Claire
authors.initials: C
authors.lastname: Berger
authors.forename: Chun Ning
authors.initials: CN
authors.lastname: Lau
authors.forename: Walt A
authors.initials: WA
authors.lastname: deHeer
authors.forename: Edward H
authors.initials: EH
authors.lastname: Conrad
authors.forename: Robert C
authors.initials: RC
authors.lastname: Haddon