Field emission of electrons generated by the near field of strongly coupled plasmons

Field emission of electrons is generated solely by the ultrastrong near-field of strongly coupled plasmons without the help of a noticeable dc field. Strongly coupled plasmons are excited at Au nanoparticles in subnanometer distance to a Au film by femtosecond laser pulses. Field-emitted electrons from individual nanoparticles are detected by means of photoelectron emission microscopy and spectroscopy. The dependence of total electron yield and kinetic energy on the laser power proves that field emission is the underlying emission process. We derive a dynamic version of the Fowler-Nordheim equation that yields perfect agreement with the experiment.

Localized multiphoton emission of femtosecond electron pulses from metal nanotips

Intense multiphoton electron emission is observed from sharp (approximately 20 nm radius) metallic tips illuminated with weak 100-pJ, 7-fs light pulses. Local field enhancement, evidenced by concurrent nonlinear light generation, confines the emission to the tip apex. Electrons are emitted from a highly excited nonequilibrium carrier distribution, resulting in a marked change of the absolute electron flux and its dependence on optical power with the tip bias voltage. The strong optical nonlinearity of the electron emission allows us to image the local optical field near a metallic nanostructure with a spatial resolution of a few tens of nanometers in a novel tip-enhanced electron emission microscope.

Surface-plasmon-enhanced multiphoton photoelectric emission from thin silver films

We report the enhancement of multiphoton photoelectric emission, from a thin silver film, by surface plasmons excited at the single-metal-vacuum interface. The surface plasmons are resonantly pumped by femtosecond laser pulses in the Kretchmann attenuated-total-internal-reflection configuration. A quantum yield approaching 2 x 10(-8) at a photon fluence of 10 MW/cm (2) from a two-photon process was observed, which is 5 x 10(3) higher than that of the bulk emission measured for the same film at the same power fluence.