Field emission microscopy pattern of a single-crystal diamond needle under ultrafast laser illumination

We report herein on the spatial beam properties of a field emission electron source based on a single-crystal diamond needle illuminated by ultrashort light pulses. We show that the increasing of the laser intensity strongly modifies the emission pattern, leading to the emergence of a new emission r...

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Bibliographic Details
Published in:New journal of physics 2019-11, Vol.21 (11), p.113060
Main Authors: Mammez, M H, Borz, M, Blum, I, Moldovan, S, Arnoldi, L, Idlahcen, S, Hideur, A, Kleshch, V I, Obraztsov, A N, Vella, A
Format: Article
Language:English
Subjects:
Computer simulation
diamond
Diamonds
electron spectroscopy
Electrons
Emissions control
Emitters (electron)
field emission
Field emission microscopy
Illumination
Laser beams
Lasers
Light
Light diffraction
Luminous intensity
nanoemitters
Optics
Photon absorption
Physics
Single crystals
Surface roughness
ultrafast laser
Ultrafast lasers
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Summary:We report herein on the spatial beam properties of a field emission electron source based on a single-crystal diamond needle illuminated by ultrashort light pulses. We show that the increasing of the laser intensity strongly modifies the emission pattern, leading to the emergence of a new emission region at high peak power. This region is situated on the opposite side of the diamond needle to the one irradiated by the laser. By spatially-resolved energy spectrometry, we prove that the electrons emitted from this region are governed by a multi-photon absorption process. The occurrence of this emission pattern can be explained by accounting for the inhomogeneous distribution of the optical field enhancement and the laser absorption induced by light diffraction within the nanometric needle. The numerical simulations performed on a real sub-wavelength tip confirm this localization of the optical field enhancement and reveal that the electrons trajectories match the spatial beam distribution evidenced experimentally. This work underlines the need to closely monitor the surface roughness of the field emitter as well as the laser illumination conditions to finely control its emission pattern.
ISSN:1367-2630
1367-2630
DOI:10.1088/1367-2630/ab5857