Investigation of the photoionization process of helium ion in bichromatic circularly XUV fields with different time delays

Cross-channel contributions to vortex patterns in photoionization by a pair of counter-rotating circularly polarized attosecond pulses

“…The discrepancies in the brightness of the vortex patterns are caused by the interference of the different ionization pathways, then the total interferences can be written as sums of the interference terms: (1,2) + W (1,3) + W (2,3) = σ 1 σ 2 (f (1,2) + f (1,3) + f (2,3) ), (16) where f (1,2) + f (1,3) + f (2,3) = 2 cos(4θ The first term in eq. ( 17) represents the interferences between pathways Γ 11 and Γ 22 , which gives the photoelectron angular distributions without considering the cross-channel contributions.…”

“…where β = 1 a.u., and we set the boundary of the ionization wave function r b = 20 a.u. [16]. Then the PMDs can be obtained by Fourier transform from the ionized wave function.…”

“…In the research, a variety of pulse combinations have been used to explore the different physical phenomena, such as the high-order harmonic generation (HHG) [9][10][11][12], nonsequential double ionization (NSDI) [13][14][15], and the photoelectron momentum distribution (PMD) [16][17][18][19][20]. Yuan et al [21] theoretically investigated the molecular photoelectron interference effects by intense circularly polarized attosecond x-ray pulses.…”

Photoelectron momentum distributions of single-photon ionization under a pair of elliptically polarized attosecond laser pulses*

“…After the end of the laser pulse, the wave function further propagates for an additional ten optical cycles to ensure that all the ionized components move away from the core. Then we obtain the ionized wave function, ψ ion (x, y) = M(r b )ψ final (x, y), in the range of x 2 + y 2 > 50 a.u., where ψ final (x, y) is the wave packet at final time, M(r b ) is an absorption function in the form of [32] M(r…”

Molecular Free Electron Vortices in Photoionization by Polarization-Tailored Ultrashort Laser Pulses

“…Introducing a time-delay τ between two counterrotating circularly polarized subpulses results in an “unusual kind of Ramsey interference” Ngoko Djiokap et al (2015) , which gives rise to an azimuthal interference pattern in the photoelectron momentum distribution (PMD) forming a multi-armed Archimedean spiral. Atomic FEVs have been studied theoretically employing different numerical methods, including the ab initio solution of the time-dependent Schrödinger equation (TDSE) ( Ngoko Djiokap et al 2015; Ngoko Djiokap et al, 2016 ; Djiokap and Starace., 2017 ; Ngoko Djiokap et al, 2017 ; Ivanov et al, 2017 ; Jia et al, 2019 ; Xiao et al, 2019 ; Bayer et al, 2020 ; Qin et al, 2020 ; Wang et al, 2020 ; Zhen et al, 2020 ; Geng et al, 2020 ; Maxwell et al, 2020 ; Djiokap et al, 2021 ; Geng et al, 2021 ), calculations based on the strong-field approximation ( Hasović et al, 2016 ; Ivanov et al, 2017 ; Li M. et al, 2017 ; Li et al, 2018a ; Li et al, 2018b ; Gazibegović-Busuladžić et al, 2018 ; Kong et al, 2018 ; Li et al, 2019b ; Xiao et al, 2019 ; Geng et al, 2020 ; Maxwell et al 2020 ; Qin et al, 2020 ; Geng et al, 2021 ; Becker and Milošević, 2022) , perturbative analytical approaches ( Ngoko Djiokap et al, 2015; Ngoko Djiokap et al, 2016 ; Djiokap and Starace, 2017 ; Ngoko Djiokap et al, 2017 ; Djiokap et al, 2021 ), emerging techniques such as the -matrix with time-dependence theory ( Clarke et al, 2018 ; Armstrong et al, 2019 ; Maxwell et al, 2020 ) and semi-classical Monte-Carlo methods ( Ben et al, 2020) . Current research topics comprise the creation of FEVs with odd rotational symmetry using bichromatic pulse sequences ( Ngoko Djiokap et al, 2016) , the study of electron-electron correlations in atomic double-ionization ( Djiokap and Starace, 2017 ; Ngoko Djiokap et al, 2017 ), the influence of the AC-Stark effect on FEVs from strong-field ionization (…”