3 research outputs found
Laser-induced Field Emission from Tungsten Tip: Optical Control of Emission Sites and Emission Process
Field-emission patterns from a clean tungsten tip apex induced by femtosecond
laser pulses have been investigated. Strongly asymmetric field-emission
intensity distributions are observed depending on three parameters: (1) the
polarization of the light, (2) the azimuthal and (3) the polar orientation of
the tip apex relative to the laser incidence direction. In effect, we have
realized an ultrafast pulsed field-emission source with site selectivity of a
few tens of nanometers. Simulations of local fields on the tip apex and of
electron emission patterns based on photo-excited nonequilibrium electron
distributions explain our observations quantitatively. Electron emission
processes are found to depend on laser power and tip voltage. At relatively low
laser power and high tip voltage, field-emission after two-photon
photo-excitation is the dominant process. At relatively low laser power and low
tip voltage, photoemission processes are dominant. As the laser power
increases, photoemission from the tip shank becomes noticeable.Comment: 12 pages, 12 figures, submitted to Physical Review
Optical Control of Field-Emission Sites by Femtosecond Laser Pulses
We have investigated field emission patterns from a clean tungsten tip apex
induced by femtosecond laser pulses. Strongly asymmetric modulations of the
field emission intensity distributions are observed depending on the
polarization of the light and the laser incidence direction relative to the
azimuthal orientation of tip apex. In effect, we have realized an ultrafast
pulsed field-emission source with site selectivity on the 10 nm scale.
Simulations of local fields on the tip apex and of electron emission patterns
based on photo-excited nonequilibrium electron distributions explain our
observations quantitatively.Comment: 4 pages, submitted to Physical Review Letter