TY - JOUR
AU - J. Venzke
AU - Andreas Becker
AU - Agnieszka Jaron-Becker
AB - 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 Schrodinger equation in single-active-electron approximation. Results of calculations show that the reconstruction technique works well for peak laser intensities less than 10(13) W/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.
BT - Physical Review A
DA - 2021-04
DO - 10.1103/physreva.103.042808
IS - 4
N2 - 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 Schrodinger equation in single-active-electron approximation. Results of calculations show that the reconstruction technique works well for peak laser intensities less than 10(13) W/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.
PB - American Physical Society (APS)
PY - 2021
T2 - Physical Review A
TI - Imaging ring-current wave packets in the helium atom
VL - 103
SN - 2469-9926, 2469-9934
ER -