Search Results
Imaging of carrier-envelope phase effects in above-threshold ionization with intense few-cycle laser fields
2008, Kling, M.F., Rauschenberger, J., Verhoef, A.J., Hasović, E., Uphues, T., Milošević, D.B., Muller, H.G., Vrakking, M.J.J.
Sub-femtosecond control of the electron emission in above-threshold ionization of the rare gases Ar, Xe and Kr in intense few-cycle laser fields is reported with full angular resolution. Experimental data that were obtained with the velocity-map imaging technique are compared to simulations using the strong-field approximation (SFA) and full time-dependent Schrödinger equation (TDSE) calculations. We find a pronounced asymmetry in both the energy and angular distributions of the electron emission that critically depends on the carrier-envelope phase (CEP) of the laser field. The potential use of imaging techniques as a tool for single-shot detection of the CEP is discussed. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.
Interference in strong-field ionization of a two-centre atomic system
2008, Ansari, Z., Böttcher, M., Manschwetus, B., Rottke, H., Sandner, W., Verhoef, A., Lezius, M., Paulus, G.G., Saenz, A., Milošević, D.B.
Strong-field photoionization of argon dimers by a few-cycle laser pulse is investigated using electron-ion coincidence momentum spectroscopy. The momentum distribution of the photoelectrons exhibits interference due to the emission from the two atomic argon centres, in analogy with a Young's doubleslit experiment. However, a simulation of the dimer photoelectron momentum spectrum based on the atomic spectrum supplemented with a theoretically derived interference term leads to distinct deviations from the experimental result. The deviations may have their origin in a complex electron dynamics during strong-field ionization of the Ar2 dimer. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.
Zuverlässigkeitsanalytik brillanter Hochleistungs-Diodenlaser in industrierelevanten Betriebsregimen - TRUST : Schlussbericht des MBI ; Verbundprojekt TRUST im BRIOLAS-Projektverband
2008, Tomm, Jens W., Weik, Fritz, Ziegler, Mathias, Schwirzke-Schaaf, Sandy, Grunske, Tobias
[no abstract available]
Machbarkeitsstudie für ein industrieorientiertes, innovatives Applikationslabor zum Transfer von Röntgentechnologien höchster räumlicher und zeitlicher Auflösung
2009, MBI
[no abstract available]
Attosecond electron thermalization in laser-induced nonsequential multiple ionization: Hard versus glancing collisions
2008, Liu, X., De Morisson Faria, C.F., Becker, W.
A recollision-based largely classical statistical model of laser-induced nonsequential multiple (N-fold) ionization of atoms is further explored. Upon its return to the ionic core, the first-ionized electron interacts with the other N - 1 bound electrons either through a contact or a Coulomb interaction. The returning electron may leave either immediately after this interaction or join the other electrons to form a thermalized complex which leaves the ion after the delay Δt, which is the sum of a thermalization time and a possible additional dwell time. Good agreement with the available triple and quadruple ionization data in neon and argon is obtained with the contact scenario and delays of Δt = 0.17 T and 0.265 T, respectively, with T the laser period. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.
Ultrafast optical excitations of metallic nanostructures: From light confinement to a novel electron source
2007, Ropers, C., Elsaesser, T., Cerullo, G., Zavelani-Rossi, M., Lienau, C.
Combining ultrafast coherent spectroscopy with nano-optical microscopy techniques offers a wealth of new possibilities for exploring the structure and function of nanostructures. In this paper, we describe newly developed nano-optical methods based on short-pulse laser sources with durations in the 10 fs regime. These techniques are used to unravel some of the intricate dynamics of elementary excitations in metallic nanostructures. Specifically, we explore light localization and storage in plasmonic crystals, demonstrate field enhancement and second harmonic generation from metallic nanotips and describe a novel nanometre-sized source of electron pulses. The rapid progress in this area offers exciting new prospects for probing and controlling electron dynamics in metallic nanostructures with femtosecond temporal and nanometre spatial resolution. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.
Method for computing the nonlinear refractive index via Keldysh theory
2008, Brée, Carsten, Demircan, Ayhan, Steinmeyer, Günter
By making use of the multiphoton limit of Keldysh theory, we show that for the case of two-photon absorption a Kramers-Kronig expansion can be used to calculate the nonlinear refractive index for different wavelenghts. We apply this method to various inert gases and compare the obtained numerical values to different experimental and theoretical results for the dispersion of the Kerr nonlinearity.
Towards time resolved core level photoelectron spectroscopy with femtosecond x-ray free-electron lasers
2008, Pietzsch, A., Föhlisch, A., Beye, M., Deppe, M., Hennies, F., Nagasono, M., Suljotil, E., Wurth, W., Gahl, C., Dörich, K., Melnikov, A.
We have performed core level photoelectron spectroscopy on a W(110) single crystal with femtosecond XUV pulses from the free-electron laser at Hamburg (FLASH). We demonstrate experimentally and through theoretical modelling that for a suitable range of photon fluences per pulse, time-resolved photoemission experiments on solid surfaces are possible. Using FLASH pulses in combination with a synchronized optical laser, we have performed femtosecond time-resolved core-level photoelectron spectroscopy and observed sideband formation on the W 4f lines indicating a cross correlation between femtosecond optical and XUV pulses. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.
Plasma induced pulse breaking in filamentary self-compression
2009, Brée, Carsten, Demircan, Ayhan, Skupin, Stefan, Berg´e, Luc, Steinmeyer, Günter
A plasma induced temporal break-up in filamentary propagation has recently been identified as one of the key events in the temporal self-compression of femtosecond laser pulses. An analysis of the Nonlinear Schrödinger Equation coupled to a noninstantaneous plasma response yields a set of stationary states. This analysis clearly indicates that the emergence of double-hump, characteristically asymmetric temporal on-axis intensity profiles in regimes where plasma defocusing saturates the optical collapse caused by Kerr self-focusing is an inherent property of the underlying dynamical model.
Femtosekunden-Strahlquelle auf der Basis von Hochleistungshalbleiterlasern - FEMTO-DIODE, Teilvorhaben: Femtosekunden-Halbleiterscheibenlaser : Abschlussbericht
2008, Griebner, Uwe, Saas, Florian, Klopp, Peter
[no abstract available]