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Laser-induced field emission from a tungsten tip: Optical control of emission sites and the emission process


Yanagisawa, H; Hafner, C; Doná, P; Klöckner, M; Leuenberger, D; Greber, T; Osterwalder, J; Hengsberger, M (2010). Laser-induced field emission from a tungsten tip: Optical control of emission sites and the emission process. Physical Review. B, Condensed Matter and Materials Physics, 81(11):115429.

Abstract

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: (i) the polarization of the light, (ii) the azimuthal, and (iii) 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 photoexcited 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 photoexcitation 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.

© 2010 The American Physical Society

Abstract

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: (i) the polarization of the light, (ii) the azimuthal, and (iii) 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 photoexcited 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 photoexcitation 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.

© 2010 The American Physical Society

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Physics Institute
Dewey Decimal Classification:530 Physics
Language:English
Date:2010
Deposited On:15 Feb 2011 20:03
Last Modified:05 Apr 2016 14:46
Publisher:American Physical Society
ISSN:1098-0121
Publisher DOI:https://doi.org/10.1103/PhysRevB.81.115429
Related URLs:http://arxiv.org/abs/1001.5375v1

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