1 research outputs found
Momentum Distribution of Electrons Emitted from Resonantly Excited Individual Gold Nanorods
Electron emission
by femtosecond laser pulses from individual Au
nanorods is studied with a time-of-flight momentum resolving photoemission
electron microscope (ToF k-PEEM). The Au nanorods adhere to a transparent
indium–tin oxide substrate, allowing for illumination from
the rear side at normal incidence. Localized plasmon polaritons are
resonantly excited at 800 nm with 100 fs long pulses. The momentum
distribution of emitted electrons reveals two distinct emission mechanisms:
a coherent multiphoton photoemission process from the optically heated
electron gas leads to an isotropic emission distribution. In contrast,
an additional emission process resulting from the optical field enhancement
at both ends of the nanorod leads to a strongly directional emission
parallel to the nanorod’s long axis. The relative intensity
of both contributions can be controlled by the peak intensity of the
incident light