title: Quantifying defects in graphene via Raman spectroscopy at different excitation energies.
abstract: We present a Raman study of Ar(+)-bombarded graphene samples with increasing ion doses. This allows us to have a controlled, increasing, amount of defects. We find that the ratio between the D and G peak intensities, for a given defect density, strongly depends on the laser excitation energy. We quantify this effect and present a simple equation for the determination of the point defect density in graphene via Raman spectroscopy for any visible excitation energy. We note that, for all excitations, the D to G intensity ratio reaches a maximum for an interdefect distance ∼3 nm. Thus, a given ratio could correspond to two different defect densities, above or below the maximum. The analysis of the G peak width and its dispersion with excitation energy solves this ambiguity.
authors.affiliation: Departamento de Física, Universidade Federal de Minas Gerais, 30123-970, Belo Horizonte, Brazil. cancado@fisica.ufmg.br
authors.forename: L G
authors.initials: LG
authors.lastname: Cançado
authors.forename: A
authors.initials: A
authors.lastname: Jorio
authors.forename: E H Martins
authors.initials: EH
authors.lastname: Ferreira
authors.forename: F
authors.initials: F
authors.lastname: Stavale
authors.forename: C A
authors.initials: CA
authors.lastname: Achete
authors.forename: R B
authors.initials: RB
authors.lastname: Capaz
authors.forename: M V O
authors.initials: MV
authors.lastname: Moutinho
authors.forename: A
authors.initials: A
authors.lastname: Lombardo
authors.forename: T S
authors.initials: TS
authors.lastname: Kulmala
authors.forename: A C
authors.initials: AC
authors.lastname: Ferrari