title: Plasmonically nanoconfined light probing invisible phonon modes in defect-free graphene.
abstract: We present a simple plasmonic method that enables tuning of accessibility to the dipole-forbidden transition states of matter. This technique is realized by well-controlled plasmonic dimers, which can confine optical fields on the order of molecular dimensions. As an example, the approach is applied to activate invisible noncenter phonon modes of defect-free graphene in resonance Raman spectra. The relative intensity of the normally forbidden modes with respect to the dipole allowed modes progressively increases as the degree of field confinement increases. This opens up a novel avenue for both photochemical excitation of molecular systems and nanoscale characterization of materials.
authors.affiliation: Division of Chemistry, Graduate School of Science, Hokkaido University, Sapporo 060-0810, Japan. kikeda@pchem.sci.hokudai.ac.jp
authors.forename: Katsuyoshi
authors.initials: K
authors.lastname: Ikeda
authors.forename: Mai
authors.initials: M
authors.lastname: Takase
authors.forename: Norihiko
authors.initials: N
authors.lastname: Hayazawa
authors.forename: Satoshi
authors.initials: S
authors.lastname: Kawata
authors.forename: Kei
authors.initials: K
authors.lastname: Murakoshi
authors.forename: Kohei
authors.initials: K
authors.lastname: Uosaki