title: Low temperature raman study of the electron coherence length near graphene edges.
abstract: We developed a novel optical defocusing method for studying spatial coherence of photoexcited electrons and holes near edges of graphene. Our method is applied to measure the localization l(D) of the disorder-induced Raman D band (∼1350 cm(-1)) with a resolution of a few nanometers. Raman scattering experiments performed in a helium bath cryostat reveal that as temperature is decreased from 300 to 1.55 K, the length l(D) increases. We found that the localization of the D band varies as 1/T(1/2), giving strong evidence that l(D) scales with the coherence length of photoexcited electrons near graphene edges.
authors.affiliation: Institute of Optics, University of Rochester, Rochester, New York 14627, United States.
authors.forename: Ryan
authors.initials: R
authors.lastname: Beams
authors.forename: Luiz Gustavo
authors.initials: LG
authors.lastname: Cançado
authors.forename: Lukas
authors.initials: L
authors.lastname: Novotny