Christoph Lemell

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The kinematics of feeding on fish have been studied in the aquatic feeding specialist Chelus fimbriatus, the fringed turtle, to provide a basic description of complete feeding cycles. Anatomical findings supplement the kinematic results. High-speed video (500 frames x s(-1)) recordings and X-ray film (150 frames x s(-1)) are used to analyse the kinematic(More)
We theoretically investigate the generation of ultrafast currents in insulators induced by strong few-cycle laser pulses. Ab initio simulations based on time-dependent density functional theory give insight into the atomic-scale properties of the induced current signifying a femtosecond-scale insulator-metal transition. We observe the transition from(More)
We theoretically investigate the dependence of the enhancement of optical near-fields at nanometric tips on the shape, size, andmaterial of the tip.We confirm the strong dependence of thefield enhancement factor on the radius of curvature. In addition, we find a surprisingly strong increase of field enhancement with increasing opening angle of the nanotips.(More)
We discuss the creation of nano-sized protrusions on insulating surfaces using slow highly charged ions. This method holds the promise of forming regular structures on surfaces without inducing defects in deeper lying crystal layers. We find that only projectiles with a potential energy above a critical value are able to create hillocks. Below this(More)
We demonstrate coherent control of multiphoton and above-threshold photoemission from a single solid-state nanoemitter driven by a fundamental and a weak second harmonic laser pulse. Depending on the relative phase of the two pulses, electron emission is modulated with a contrast of the oscillating current signal of up to 94%. Electron spectra reveal that(More)
The non-linear response of matter to ultrashort laser pulses on the (sub)femtosecond scale allows controlling and steering electronic motion. Strong field interaction with condensed matter promises to eventually realize the dream of light-field electronics with devices operating on the femto-second time scale and nanometer length scale. Theoretical(More)
We analyze the two-dimensional angular momentum-energy distribution of electrons emitted from argon by short laser pulses. We identify characteristic features of both multiphoton and tunneling ionization in the partial-wave distribution for Keldysh parameters close to unity. We observe a remarkable degree of quantum-classical correspondence in the(More)
Ludger Wirtz, Carlos O. Reinhold, Christoph Lemell, and Joachim Burgdörfer 1,2,3 Institute for Theoretical Physics, Vienna University of Technology, Wiedner Hauptstrasse 8-10/136, A-1040 Vienna, Austria Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996-1200 Physics Division, Oak Ridge National Laboratory, Oak Ridge,(More)