Hannover 2010 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 27: Ultrashort Laser Pulses: Applications I

Q 27.6: Talk

Wednesday, March 10, 2010, 11:45–12:00, F 342

Strong-field photoelectron emission from metal nanotips — Reiner Bormann, Max Gulde, Sergey Yalunin, Alexander Weismann, and •Claus Ropers — University of Göttingen, Courant Research Center Nano-Spectroscopy and X-Ray Imaging, Friedrich- Hund-Platz 1, 37077 Göttingen, Germany

The generation of ultrashort, localized electron pulses is of fundamental interest for future applications in time-resolved electron imaging and diffraction. Femtosecond electron sources of great spatial coherence make use of a combination of local field enhancement at metal nanotips and nonlinear photoelectric effects. Previous studies have resulted in a controversial debate about the underlying physical processes.

Here, we present our most recent theoretical and experimental results regarding ultrafast photoelectron emission from nanometric gold tips. For the first time, we conclusively show the transition between the multiphoton and the optical field emission (i.e. tunneling) regimes. Direct evidence for this transition is found from both the power dependence of the total current and the spatial characteristics of the resulting electron beam. The results are supported by theoretical modeling.