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Holographic interferences in strong-field ionization beyond the dipole approximation: The influence of the peak and focal-volume-averaged laser intensities
摘要： In strong-?eld ionization, interferences between electron trajectories create a variety of interference structures in the ?nal momentum distributions. Among them, the interferences between electron pathways that are driven directly to the detector and those that rescatter signi?cantly with the parent ion lead to holography-type interference patterns that have received great attention in recent years. In this work, we study the in?uence of the laser magnetic-?eld component onto the holographic interference pattern, an effect beyond the electric-dipole approximation, in experiment and theory. The experimentally observed nondipole signatures are analyzed via quantum trajectory Monte Carlo simulations. We provide explanations for the experimentally demonstrated asymmetry in the holographic interference pattern and its nonuniform photoelectron energy dependence as well as for the variation of the topology of the holography-type interference pattern along the laser-?eld direction. Analytical scaling laws of the interference features are derived, and their direct relation to either the focal-volume-averaged laser intensities, or to the peak intensities are identi?ed. The latter, in particular, provides direct access to the peak intensity in the focal volume.
关键词： laser magnetic-?eld,nondipole effects,strong-?eld ionization,quantum trajectory Monte Carlo simulations,holographic interference
更新于2025-09-12 10:27:22
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Pulse-length effects in strong-field ionization of atoms by co-rotating and counter-rotating bicircular laser pulses
摘要： We study strong-?eld ionization of H and selected rare-gas atoms by solving the three-dimensional time-dependent Schr?dinger equation in the single-active-electron approximation with particular attention to the effect of pulse length on the total ionization yields (TIYs) produced by counter-rotating bicircular (CRBC) lasers compared to co-rotating bicircular (COBC) lasers. To this end, TIYs, photoelectron momentum distributions, and above-threshold ionization spectra are presented for various pulse durations and peak intensities. For pulses containing ?ve or more cycles of the fundamental near-infrared laser ?eld, the CRBC/COBC ratio of TIYs is affected due to ionization via excited states and multiphoton ionization channels. For pulses containing less than ?ve cycles, the CRBC/COBC ratio of TIYs depends on both the frequency combination and number of optical cycles: With the 1ω-2ω frequency combination, the ratio of TIYs is enhanced (reduced) for pulses with an odd (even) number of optical cycles. The 1ω-3ω frequency combination was considered for pulses containing two or three optical cycles, and for both pulse lengths the CRBC/COBC ratio of TIYs is less than unity.
关键词： photoelectron momentum distributions,bicircular laser pulses,time-dependent Schr?dinger equation,above-threshold ionization spectra,strong-?eld ionization
更新于2025-09-11 14:15:04
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Effect of multiorbital contributions to strong-field ionization of benzene derivatives
摘要： Strong-?eld ionization of benzene, ?uorobenzene, benzonitrile, and 1-chloro-2-?uorobenzene is studied within the framework of real-space and real-time time-dependent density functional theory. Analysis of the ionization rates as a function of the molecule orientation reveals a signi?cant contribution from multiple inner Kohn-Sham orbitals that depends on the electronic structure and on the orbital symmetries of the molecule, as well as on the polarization and intensity of the external laser ?eld. Calculated photoelectron angular distributions at different molecular orientations and in response to laser ?elds with different degrees of ellipticity further demonstrate the spatial dependency of the orbital ionization rates.
关键词： orbital symmetries,time-dependent density functional theory,strong-?eld ionization,benzene derivatives,photoelectron angular distributions
更新于2025-09-10 09:29:36