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A: Fachverband Atomphysik
A 9: Poster Session - Atomic Physics I
A 9.4: Poster
Montag, 9. März 2020, 16:00–18:00, Empore Lichthof
Continuum-Continuum Recombination in High-Order Harmonic Generation — •Fermin Rodriguez Hernandez1, Frank Grossmann2, and Jan Michael Rost1 — 1Max-Planck-Institut für Physik komplexer Systeme, Dresden, Germany — 2Institut für Theoretische Physik, Technische Universität Dresden, Dresden, Germany
The generation of high-order harmonics (HHG) in a model atomic system is investigated using both: the traditional ground state scheme and the laser-assisted collision scenario. We find strong signatures of continuum-continuum transitions in the HHG spectra when the laser intensity is sufficiently high, i.e., in the over-the-barrier ionization regime. They consist in a double plateau structure with a characteristic first cutoff frequency ωCC=1.85Up in the ground state scheme and ωCC=1.67Up in the laser-assisted collision scenario. We demonstrate analytically that ωCC=1.85Up originates by the coherent interference of the second and first collision of electronic wavepackets generated every half of the laser period, respectively. In the laser-assisted collision scenario, ωCC=1.67Up rises after the interference of two components of the continuum wavepacket, which can be associated with two classes of recolliding trajectories known as free and stranded trajectories, respectively. Differences between 1D and 3D realizations will be discussed.