0000000000189662
AUTHOR
Martin Lehr
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 enhanceme…
Evidence of Spatially Inhomogeneous Electron Temperature in a Resonantly Excited Array of Bow-Tie Nanoantennas
We studied the excitation of large-area Au bow-tie nanoantenna arrays, which we have fabricated on indium-tin-oxide (ITO)-coated glass substrates using colloidal lithography with nanoscale polystyr...
Robustness of plasmonic angular momentum confinement in cross resonant optical antennas
Using a combination of photoemission electron microscopy and numerical simulations, we investigated the angular moment transfer in strongly enhanced optical near-fields of artificially fabricated optical antennas. The polarization dependence of the optical near-field enhancement has been measured in a maximum symmetric geometry, i.e., excitation by a normal incident planar wave. Finite-difference time-domain simulations for the realistic antenna geometries as determined by high-resolution electron microscopy reveal a very good agreement with experimental data. The agreement confirms that the geometrical asymmetries and inhomogeneities due to the nanoscale fabrication process preserve the ci…
Spin-polarized photoelectrons resonantly excited by circularly polarized light from a fractional Ag film on GaAs(100)
We demonstrate a finite spin polarization of photoelectrons emitted from GaAs(100) covered by a fractional Ag film. The photoemission yield shows a sharp maximum for intermediate coverage and the spin polarization increases with increasing laser intensity. Photoelectrons are excited by circularly polarized 100 fs laser pulses of 800 nm wavelength. We recorded the photoemitted electrons using a photoemission electron microscope combined with a Mott spin polarimeter. The spin polarization is analyzed in dependence on the excitation frequency and intensity and on the average thickness of the silver film. The results are explained by a model combining multiphoton photoemission and optical field…