title: Phonon softening and crystallographic orientation of strained graphene studied by Raman spectroscopy.
abstract: We present a systematic study of the Raman spectra of optical phonons in graphene monolayers under tunable uniaxial tensile stress. Both the G and 2D bands exhibit significant red shifts. The G band splits into 2 distinct subbands (G(+), G(-)) because of the strain-induced symmetry breaking. Raman scattering from the G(+) and G(-) bands shows a distinctive polarization dependence that reflects the angle between the axis of the stress and the underlying graphene crystal axes. Polarized Raman spectroscopy therefore constitutes a purely optical method for the determination of the crystallographic orientation of graphene.
authors.affiliation: Department of Mechanical Engineering, Columbia University, New York, NY 10027, USA.
authors.forename: Mingyuan
authors.initials: M
authors.lastname: Huang
authors.forename: Hugen
authors.initials: H
authors.lastname: Yan
authors.forename: Changyao
authors.initials: C
authors.lastname: Chen
authors.forename: Daohua
authors.initials: D
authors.lastname: Song
authors.forename: Tony F
authors.initials: TF
authors.lastname: Heinz
authors.forename: James
authors.initials: J
authors.lastname: Hone