title: Excitation of propagating surface plasmons with a scanning tunnelling microscope.
abstract: Inelastic electron tunnelling excitation of propagating surface plasmon polaritons (SPPs) on a thin gold film is demonstrated. This is done by combining a scanning tunnelling microscope (STM) with an inverted optical microscope. Analysis of the leakage radiation in both the image and Fourier planes unambiguously shows that the majority (up to 99.5%) of the detected photons originate from propagating SPPs with propagation lengths of the order of 10  µm. The remaining photon emission is localized under the STM tip and is attributed to a tip-gold film coupled plasmon resonance as evidenced by the bimodal spectral distribution and enhanced emission intensity observed using a silver STM tip for excitation.
authors.affiliation: Institut des Sciences Moléculaire d'Orsay (ISMO), CNRS Université Paris-Sud, 91405 Orsay, France.
authors.forename: T
authors.initials: T
authors.lastname: Wang
authors.forename: E
authors.initials: E
authors.lastname: Boer-Duchemin
authors.forename: Y
authors.initials: Y
authors.lastname: Zhang
authors.forename: G
authors.initials: G
authors.lastname: Comtet
authors.forename: G
authors.initials: G
authors.lastname: Dujardin