RESUMEN
We report on infrared (IR) nanoscopy of 2D plasmon excitations of Dirac fermions in graphene. This is achieved by confining mid-IR radiation at the apex of a nanoscale tip: an approach yielding 2 orders of magnitude increase in the value of in-plane component of incident wavevector q compared to free space propagation. At these high wavevectors, the Dirac plasmon is found to dramatically enhance the near-field interaction with mid-IR surface phonons of SiO(2) substrate. Our data augmented by detailed modeling establish graphene as a new medium supporting plasmonic effects that can be controlled by gate voltage.
Asunto(s)
Grafito/química , Grafito/efectos de la radiación , Modelos Químicos , Nanoestructuras/química , Nanoestructuras/efectos de la radiación , Dióxido de Silicio/química , Dióxido de Silicio/efectos de la radiación , Resonancia por Plasmón de Superficie/métodos , Simulación por Computador , Rayos Infrarrojos , Ensayo de Materiales , Tamaño de la PartículaRESUMEN
We analyze electrostatic interaction between a sharp conducting tip and a thin one-dimensional wire, e.g., a carbon nanotube, in a scanned gate microscopy (SGM) experiment. The problem is analytically tractable if the wire resides on a thin dielectric substrate above a metallic backgate. The characteristic spatial scale of the electrostatic coupling to the tip is equal to its height above the substrate. Numerical simulations indicate that imaging of individual electrons by SGM is possible once the mean electron separation exceeds this scale (typically, a few tens of nm). Differences between weakly and strongly invasive SGM regimes are pointed out.