Imaging ring-current wave packets in the helium atom
| Autor: | Andreas Becker, Joel Venzke, Agnieszka Jaron-Becker |
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| Rok vydání: | 2021 |
| Předmět: | |
| Zdroj: | Physical Review A. 103 |
| ISSN: | 2469-9934 2469-9926 |
| DOI: | 10.1103/physreva.103.042808 |
| Popis: | We study the reconstruction of a wave packet and the corresponding electron dynamics in an atom via photoelectron angular distributions (PADs) in a pump-probe scheme as a function of time delay. The method is applied to the superposition of ground and one or two excited states in helium atom representing field-free charge migrations on the attosecond timescale in form of ring currents around the core. It is based on the interference between one- and two-photon transitions from ground and excited states into the continuum. In the reconstruction predictions of first- and second-order perturbation theory are used to determine the unknown phases and amplitudes from the PADs, which we simulate via solutions of the time-dependent Schr\"odinger equation in single-active-electron approximation. Results of calculations show that the reconstruction technique works well for peak laser intensities less than ${10}^{13}$ $\mathrm{W}/{\mathrm{cm}}^{2}$. Knowledge of the electric field of the probe pulse is required with shot-to-shot variations of carrier-to-envelope phase and peak intensity of up to 10% and 20%, respectively. The relevance of different one- and two-photon pathways for the reconstruction as a function of peak intensity and pulse duration is analyzed---specifically their role for ultrashort probe pulses with broad bandwidths. |
| Databáze: | OpenAIRE |
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