Phasen- und polarisations-gesteuerte starke Nahfeld-Elektronendynamik bei isolierten Nanopartikeln
Zusammenfassung der Projektergebnisse
When applied to an atom a strong laser field can induce electron emission from the bound states into the continuum via quantum tunnelling. As the ionization probability depends exponentially on the field strength the electron emission happens preferentially during the peaks of the laser field. This intrinsic synchronization of the electron emission with the driving field lies at the basis of the control of the emission process with sub-cycle precision. With recent advancements in generation of controlled laser waveforms the strong field ionisation dynamics has been intensively studied both experimentally and theoretically. In angular streaking experiments elliptically polarised laser pulses were applied to both ionize the gas target and steer the resulting electron emission using the same laser pulse. There the electrons are preferably ionized when the field is at maximum and points along the major axis of the polarization ellipse. The angle between the major axis and the preferential electron emission direction, which is the main observable in this type of experiments, thus contains information on the quantum tunnelling and subsequent propagation in the combined laser and the parent ion field. These studies sparkled an intense ongoing debate on the tunneling time and its interpretation. As compared to the atomic gases the strong field ionization from solids is more complex due to e.g. the electron band dynamics, surface and many-particle charge interactions. Here we extend the angular streaking approach to study the strong field ionization in solid materials. For that we illuminated a beam of isolated nanoparticles with near circularly polarized laser pulses. Isolated nanospheres are especially suited for these studies as the spherical shape of the particles preserves cylindrical symmetry of the electron emission induced by circularly polarized laser fields. As a first test we selected two materials (SiO2 and polystyrene) with similar dielectric response but considerably different electron binding energies. The resulting electron emission distributions exhibit quite different patterns for these two materials. We compared the experimental results with a semi-classical trajectory-based model. The comparison shows that in case of the polystyrene the electron distributions are dominated by the many particle charge interactions and are not sensitive to characteristics of the initial ionization step. It is different for the SiO2, where the results are quite sensitive to the simulation details of the initial step, e.g. to the starting position of the electron trajectory. This suggest a potential of the proposed approach for studies of strong field ionization in solid materials.
Projektbezogene Publikationen (Auswahl)
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Waveform control of electron emission from isolated nanospheres with circularly polarized two-color laser fields, ICEL 2017, ELI-ALPS Research Institute
D. Zietlow
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Ionization-Induced Subcycle Metallization of Nanoparticles in Few-Cycle Pulses. ACS Photonics, 7(11), 3207-3215.
Liu, Qingcao; Seiffert, Lennart; Süßmann, Frederik; Zherebtsov, Sergey; Passig, Johannes; Kessel, Alexander; Trushin, Sergei A.; Kling, Nora G.; Ben-Itzhak, Itzik; Mondes, Valerie; Graf, Christina; Rühl, Eckart; Veisz, Laszlo; Karsch, Stefan; Rodrı́guez-Fernández, Jessica; Stockman, Mark I.; Tiggesbäumker, Josef; Meiwes-Broer, Karl-Heinz; Fennel, Thomas & Kling, Matthias F.
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Few-femtosecond resolved imaging of laser-driven nanoplasma expansion. New Journal of Physics, 24(4), 043024.
Peltz, C.; Powell, J. A.; Rupp, P.; Summers, A.; Gorkhover, T.; Gallei, M.; Halfpap, I.; Antonsson, E.; Langer, B.; Trallero-Herrero, C.; Graf, C.; Ray, D.; Liu, Q.; Osipov, T.; Bucher, M.; Ferguson, K.; Möller, S.; Zherebtsov, S.; Rolles, D.; ... & Fennel, T.
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Strong-field physics with nanospheres. Advances in Physics: X, 7(1).
Seiffert, Lennart; Zherebtsov, Sergey; Kling, Matthias F. & Fennel, Thomas
