Ionization dynamics in two-color laser fields - "phase-of-the-phase" spectroscopy and semi-classical trajectory analysis
Final Report Abstract
Strong field ionization in two-color laser fields have been studied both experimentally and theoretically by using and further developing the so-called phase-of-the-phase (PoP) approach. In PoP spectroscopy, the momentum-resolved photoelectron yields are analyzed as a function of the relative phase φ between the two color-components of the laser field in a concise manner. Here, the n-th order PoP Φn (p) tells us with which phase lag the yields follow cos(nφ). The method was successfully applied to other systems, at other wavelengths and other ionization regimes. We found a sharp jump of the PP as a function of the photoelectron momentum for the case of circularly polarized, counter-rotating two-color laser fields. Within the strong-field approximation it was possible to calculate analytically the momentum for which this phase jump takes place. With the help of this expression the laser intensity can be calibrated with high accuracy. Further we showed how higher-order PoP can be employed if the yields are too low for photoelectron momenta where the phase flip occurs. Another important application of PoP is to gain information about the electron dynamics in complex, systems for which common photoelectron spectra appear to be structureless, i.e., almost Maxwellian. This is the case whenever the photoelectrons undergo processes that render their precise "birthtime" (i.e., ionization time) irrelevant. Examples are scattering off atoms in the environment, electron-electron interaction, electron-phonon interaction or scattering at interfaces. In such cases, PoP may nevertheless reveal the surviving laser-coherent motion in the target because the thermal, structureless part of the spectra is independent of the relative phase φ and thus will not contribute to the phase-sensitive signal. PoP thus represents a powerful tool to analyze laser-coherent electron dynamics even in complex systems as has been demonstrated in the context of above-threshold ionization from atomic impurities embedded in helium nanodroplets.
Publications
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Two-color phase-of-the-phase spectroscopy with circularly polarized laser pulses Phys. Rev. A 98, 053433 (2018)
V. Tulsky, M. A. Almajid, D. Bauer
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Photoelectron Spectroscopy on Magnesium Ensembles in Helium Nanodroplets. J. Phys. Chem. A 123, 5951 (2019)
L. Kazak, S. Göde, K.-H. Meiwes-Broer, J. Tiggesbäumker
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Accurate retrieval of ionization times by means of the phase-of-the-phase spectroscopy, and its limits. Phys. Rev. A 101, 033416 (2020)
D. Würzler, S. Skruszewicz, A. M. Sayler, D. Zille, M. Möller, P. Wustelt, Y. Zhang, J. Tiggesbäumker, G. G. Paulus
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Numerical time-of-flight analysis of the strong-field photoeffect. Phys. Rev. Research 2, 043083 (2020)
V. A. Tulsky, D. Bauer
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QPROP with faster calculation of photoelectron spectra. Comput. Phys. Commun. 251, 107098 (2020)
V. Tulsky, D. Bauer
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Revealing laser-coherent electron features using phase-of-the-phase spectroscopy. J. Phys. B: At. Mol. Opt. Phys. 53, 074001 (2020)
V.A. Tulsky, B. Krebs, J. Tiggesbäumker, D. Bauer
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Temporal development of a laser-induced helium nanoplasma measured through Auger emission and above-threshold ionization. Phys. Rev. Lett. 125, 093202 (2020)
M. Kelbg, M. Zabel, B. Krebs, L. Kazak, K.-H. Meiwes-Broer, J. Tiggesbaeumker
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Phase-of-the-phase electron momentum spectroscopy on single metal atoms in helium nanodroplets. J. Phys. Chem Lett. 13, 1526 (2022)
B. Krebs, V. A. Tulsky, L. Kazak, M. Zabel, D. Bauer, J. Tiggesbäumker
