56 research outputs found
Multiphoton Ionization as Time-Dependent Tunneling
A new semiclassical approach to ionization by an oscillating field is
presented. For a delta-function atom, an asymptotic analysis is performed with
respect to a quantity h, defined as the ratio of photon energy to ponderomotive
energy. This h appears formally equivalent to Planck's constant in a suitably
transformed Schroedinger equation and allows semiclassical methods to be
applicable. Systematically, a picture of tunneling wave packets in complex time
is developped, which by interference account for the typical ponderomotive
features of ionization curves. These analytical results are then compared to
numerical simulations and are shown to be in good agreement.Comment: 36 pages (also printable half size), uuencoded compressed tarred
Latex file with 9 Postscript figures included automaticall
Resonant Structures in the Low-Energy Electron Continuum for Single Ionization of Atoms in the Tunneling Regime
We present results of high-resolution experiments on single ionization of He,
Ne and Ar by ultra-short (25 fs, 6 fs) 795 nm laser pulses at intensities
0.15-2.0x10^15 W/cm^2. We show that the ATI-like pattern can survive deep in
the tunneling regime and that the atomic structure plays an important role in
the formation of the low-energy photoelectron spectra even at high intensities.
The absence of ponderomotive shifts, the splitting of the peaks and their
degeneration for few-cycle pulses indicate that the observed structures
originate from a resonant process.Comment: 11 pages, 3 figure
Pilotstudie Radarbefliegung der Unteren Mittelelbe
Multifrequente und multipolarisierte E-SAR Flugzeugradardaten wurden mit verschiedenen Klassifizierungsverfahren und einer Hauptkomponentenanalyse zu thematischen Karten der Landoberflächen und Vegetationstypen des Elbauen- und Rückdeichungsbereiches verarbeitet. Erste Modellanwendungen verschiedener Radarrückstreumodelle habe zu Hinweisen auf die Bodenfeuchte und Oberflächenrauhigkeit geführt
Pilotstudie Radarbefliegung
Erste Ergebnisse des Pilotprojektes Radarbefliegung im BMBF-Verbundprojekt "Morphodynamik der Elbe" Zwischenbericht über Geländekampagne, Radarbefliegung, Laborarbeiten und erste Datenauswertungen
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