Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Physical Review A

Relativistic effects in time delay of atomic photoionization

Igor A. Ivanov, Anatoli S. Kheifets

Published Apr 7, 2014• 10 citations
Publisher

Abstract

We study relativistic effects in the time delay of atomic photoionization using an example of the Xe atom subjected to a circularly polarized electromagnetic pulse. We find that while relativistic effects play only a fairly small role for both the ionization probabilities and the time delay of the corotating electron with the same sign of the angular momentum projection as the circularly polarized light, these effects produce substantial change in the time delay for a counter-rotating electron with the opposite sign of the angular momentum projection.

DOI
10.1103/physreva.89.043405

Related papers

Time delay in atomic photoionization with circularly polarized light

Anatoli S. Kheifets, Igor A. Ivanov

We present a study of the time delay in atomic photo-ionization by circularly polarized laser pulse. We considered initial electron states that are co- and counter-rotating with respect to the electric field. We found, that similarly to the photoelectron spectra, studied extensively in the literature, the time delays are markedly different for these two orientations, depending sensitively on the field strengths and pulse durations.

Journal of Physics Conference Series•Apr 10, 2014•3 citations

Time delay in atomic photoionization with circularly polarized light

Igor A. Ivanov, Anatoli S. Kheifets

We study time delay in atomic photoionization by circularly polarized light. By considering the Li atom in an excited $2p$ state, we demonstrate a strong time-delay asymmetry between the photoemission of the target electrons that are co- and counter-rotating with the electromagnetic field in the polarization plane. In addition, we observe the time-delay sensitivity to the polar angle of the photoelectron emission in the polarization plane. This modulation depends on the shape and duration of the electromagnetic pulse.

Physical Review A•Mar 7, 2013•48 citations

Electron spin polarization in strong-field ionization and the effect of spin in attoclock measurements

Felipe Morales, Jivesh Kaushal, Alexander Hartung +11 more

Summary form only given. Spin plays a fundamental role in the electronic structure of matter, from single atoms and molecules through to condensed matter. However, spin dynamics and the spin response of electrons to ultra-short, strong laser pulses has remained largely unexplored until today. In 2011 and 2013, pioneering theoretical work [1, 2] extended the fundamental PPT theory [3] to treat ionization of p+ and p” electrons by circular fields. This work predicted the sensitivity of ionization probabilities in strong field ionization using circular fields to the magnetic quantum number, showing that counter rotating electrons can tunnel ionize easier. It also predicted the possibility to obtain spin polarized electrons from strong, circularly polarized fields with a high degree of efficiency. The preference of ionization was later confirmed experimentally by [4], however, the experiment in [4] did not provide a confirmation of the spin polarization predictions.

Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC)•Jun 1, 2017•0 citations

Signatures beyond the rotating-wave approximation in retrieving the photoionization time delay from an ω−2ω interferometric method

Mingqing Liu, Xinqiang Wang, Lijuan Jia +2 more

We propose a protocol to retrieve the photoionization time delay that employs a pair of oppositely circularly polarized attosecond extreme ultraviolet pulses with frequencies $\ensuremath{\omega}$ and $2\ensuremath{\omega}$. By numerically solving the three-dimensional time-dependent Schr\"odinger equation, we observe an oscillation in the energy-resolved photoionization time delay encoded in the relative optical phase between $\ensuremath{\omega}$ and $2\ensuremath{\omega}$ pulses when the emission asymmetry of the photoelectron is maximal. Our results show that this oscillation arises from the interference between two one-photon ionization pathways from the ground state due to the broad bandwidth effect of an ultrashort pulse: the absorption of one left-handed circularly polarized photon and the emission of one right-handed circularly polarized photon. The latter is regarded as a consequence of the breakdown of the rotating-wave approximation (RWA). We compare the perturbation theory with and without RWA and demonstrate that photon emission plays a crucial role in retrieving photoionization time delay. Our study enriches the underlying physics of attosecond spectroscopy and provides a framework for accurately measuring photoionization time delays in atoms and molecules.

Physical Review A•Jul 7, 2023•8 citations

Angular anisotropy parameters for photoionization delays

Soumyajit Saha, Jimmy Vinbladh, Johanna Sörngård +2 more

Anisotropy parameters describing the angular dependence of the photoionization delay are defined. The formalism is applied to results obtained with the relativistic random phase approximation with exchange for photoionization delay from the outermost $s$-orbitals in selected rare-gas atoms. Any angular dependence in the Wigner delay is induced here by relativistic effects, while the measurable atomic delay exhibits such a dependence also in the nonrelativistic limit. The contributions to the anisotropy from the different sources are disentangled and discussed. For the heavier rare gases, it is shown that measurements of the delay for electrons ejected in specific angles, relative to, e.g., those ejected along the laser polarization, are directly related here to the Wigner delay. For a considerable range of angles, the contributions from the second photon largely get canceled when the results in different angles are compared, and this angle-relative atomic delay is then close to the corresponding Wigner delay.

Physical Review A•Sep 15, 2021•9 citations

Photoelectron momentum distributions of Ne and Xe dimers in counter-rotating circularly polarized laser fields

Zhi-Xian Lei, Qing-Yun Xu, Zhijie Yang +2 more

The strong-field ionization of dimers is investigated theoretically in counter-rotating circularly polarized laser fields. By numerically solving the two-dimensional (2D) time-dependent Schrödinger equation (TDSE) with the single-electron approximation (SEA) frame, we present the photoelectron momentum distributions (PMDs) and photoelectron angular distribution (PADs) of aligned Ne and Xe dimers. It is found that the PMDs and PADs strongly depend on the time delays by counter-rotating circularly polarized laser pulses. The results can be explained by the ultrafast photoionization model and the evolution of electron wave packets for Ne and Xe dimers. Besides, We make a comparison of PMDs between Ne atom and Ne dimer.

Chinese Physics B•Jan 24, 2022•4 citations
We study relativistic effects in the time delay of atomic photoionization using an example of the Xe atom subjected to a circularly polarized electromagnetic pulse. We find that while relativistic effects play only a fairly small role for both the ionization probabilities and the time delay of the corotating electron with the same sign of the angular momentum projection as the circularly polarized light, these effects produce substantial change in the time delay for a counter-rotating electron with the opposite sign of the angular momentum projection.
We study time delay in atomic photoionization by circularly polarized light. By considering the Li atom in an excited 2p2p2p state, we demonstrate a strong time-delay asymmetry between the photoemission of the target electrons that are co- and counter-rotating with the electromagnetic field in the polarization plane. In addition, we observe the time-delay sensitivity to the polar angle of the photoelectron emission in the polarization plane. This modulation depends on the shape and duration of the electromagnetic pulse.
Summary form only given. Spin plays a fundamental role in the electronic structure of matter, from single atoms and molecules through to condensed matter. However, spin dynamics and the spin response of electrons to ultra-short, strong laser pulses has remained largely unexplored until today. In 2011 and 2013, pioneering theoretical work [1, 2] extended the fundamental PPT theory [3] to treat ionization of p+ and p” electrons by circular fields. This work predicted the sensitivity of ionization probabilities in strong field ionization using circular fields to the magnetic quantum number, showing that counter rotating electrons can tunnel ionize easier. It also predicted the possibility to obtain spin polarized electrons from strong, circularly polarized fields with a high degree of efficiency. The preference of ionization was later confirmed experimentally by [4], however, the experiment in [4] did not provide a confirmation of the spin polarization predictions.
We propose a protocol to retrieve the photoionization time delay that employs a pair of oppositely circularly polarized attosecond extreme ultraviolet pulses with frequencies $\ensuremath{\omega}$ and $2\ensuremath{\omega}$. By numerically solving the three-dimensional time-dependent Schr\"odinger equation, we observe an oscillation in the energy-resolved photoionization time delay encoded in the relative optical phase between $\ensuremath{\omega}$ and $2\ensuremath{\omega}$ pulses when the emission asymmetry of the photoelectron is maximal. Our results show that this oscillation arises from the interference between two one-photon ionization pathways from the ground state due to the broad bandwidth effect of an ultrashort pulse: the absorption of one left-handed circularly polarized photon and the emission of one right-handed circularly polarized photon. The latter is regarded as a consequence of the breakdown of the rotating-wave approximation (RWA). We compare the perturbation theory with and without RWA and demonstrate that photon emission plays a crucial role in retrieving photoionization time delay. Our study enriches the underlying physics of attosecond spectroscopy and provides a framework for accurately measuring photoionization time delays in atoms and molecules.
Anisotropy parameters describing the angular dependence of the photoionization delay are defined. The formalism is applied to results obtained with the relativistic random phase approximation with exchange for photoionization delay from the outermost sss-orbitals in selected rare-gas atoms. Any angular dependence in the Wigner delay is induced here by relativistic effects, while the measurable atomic delay exhibits such a dependence also in the nonrelativistic limit. The contributions to the anisotropy from the different sources are disentangled and discussed. For the heavier rare gases, it is shown that measurements of the delay for electrons ejected in specific angles, relative to, e.g., those ejected along the laser polarization, are directly related here to the Wigner delay. For a considerable range of angles, the contributions from the second photon largely get canceled when the results in different angles are compared, and this angle-relative atomic delay is then close to the corresponding Wigner delay.
The strong-field ionization of dimers is investigated theoretically in counter-rotating circularly polarized laser fields. By numerically solving the two-dimensional (2D) time-dependent Schrödinger equation (TDSE) with the single-electron approximation (SEA) frame, we present the photoelectron momentum distributions (PMDs) and photoelectron angular distribution (PADs) of aligned Ne and Xe dimers. It is found that the PMDs and PADs strongly depend on the time delays by counter-rotating circularly polarized laser pulses. The results can be explained by the ultrafast photoionization model and the evolution of electron wave packets for Ne and Xe dimers. Besides, We make a comparison of PMDs between Ne atom and Ne dimer.