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UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS Guest
2024-11-23 17:50 |
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Conference: Bucharest University Faculty of Physics 2014 Meeting
Section: Theoretical Physics and Applied Mathematics
Title:
Ionization of Hydrogen by a superposition of two intense high-frequency
electromagnetic pulses
Authors:
M. DONDERA(1), Viorica FLORESCU (1) and H. BACHAU (2)
Affiliation:
1) Centre for Advanced Quantum Physics, Department of Theoretical physics, Mathematics, Optics, Plasma, Lasers, University of Bucharest, Romania
2) Centre des Lasers Intenses et Applications, Universite Bordeaux I-CNRS-CEA, France
E-mail
don@barutu.fizica.unibuc.ro
Keywords:
Photoionization, stimulated Compton scattering, retardation effects
Abstract:
We present recent results obtained in a theoretical study of the photoionization of Hydrogen by a superposition of two intense electromagnetic pulses, linearly polarized along the same direction, with central frequencies in the keV range. Two types of calculations were performed: i) nonperturbative, based on the resolution of time dependent Schrodinger equation (TDSE), and treating approximately the non-dipole terms, and ii) lowest order perturbation theory (LOPT) calculations with the exact inclusion of the retardation effects. We show photoelectron energy spectra, compare the results predicted in various approximations schemes we use, and analyse their dependence on the relative direction of the two pulses. The contribution of the non-dipole terms strongly depends on the photoelectron energy range analysed. We concentrate on the stimulated Compton scattering (SCS) contribution to ionization in the case where the two central frequencies of the pulses differ by a few atomic units. This process, involving one photon absorption and one photon stimulated emission, was investigated in a recently published paper where we have shown in particular that the SCS ionization peak is very sensitive to the relative direction of the two pulses. We present results demonstrating that in some conditions the SCS importance becomes comparable with that of one photon ionization from each pulse.
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