Related papers: Separating Dipole and Quadrupole Contributions to …
A fully relativistic calculation of the double photoionization of helium-like atoms is presented. The approach is based on the partial-wave representation of the Dirac continuum states and accounts for the retardation in the…
We investigate the photo-doubleionization of $H_2$ molecules with 400 eV photons. We find that the emitted electrons do not show any sign of two-center interference fringes in their angular emission distributions if considered separately.…
We investigate two-photon double ionization of helium by intense ($10^{15} W/cm^2$) ultrashort ($\approx 300$ as) soft X-ray pulses (E = 91.6 eV). The time-dependent two-electron Schr\"odinger equation is solved using a coupled channel…
We predict breakdown of the electric dipole approximation at nonlinear Cooper minimum in direct two-photon $K-$shell atomic ionisation by circularly polarised light. According to predictions based on the electric dipole approximation, we…
In this paper, a quasistatic model is extended to describe the double ionization of Helium in intense linearly polarized field, yielding achieve an insight to the two-electron correlation effect in the ionization dynamics. Our numerical…
The double-slit interference in single-photon ionization of the diatomic molecular ion $\mathrm{H}_2^+$ is theoretically studied beyond the dipole approximation. Via simulating and comparing the interactions of the prealigned…
We analyze two-photon double ionization of helium in both the nonsequential and sequential regime. We show that the energy spacing between the two emitted electrons provides the key parameter that controls both the energy and the angular…
In the nonrelativistic many-electron approximation of the theory of photoionization of the atom in the formalism of secondary quantization and the theory of irreducible tensor operators, analytical structures for the quadrupole transition…
Double ionization of an atom by single-photon absorption in the presence of a neighbouring atom is studied. The latter is, first, resonantly photoexcited and, afterwards, transfers the excitation energy radiationlessly to the other atom,…
We calculate the photoionization with excitation-to photoionization ratios for atomic helium and heliumlike ions at intermediate values of the photon energies. The final state interactions between the electrons are included in the lowest…
We explore the influence of elliptical polarization on the (non)sequential two-photon double ionization of atomic helium with ultrashort extreme ultraviolet (XUV) light fields using time-dependent full ab-initio simulations. The energy and…
We calculate the distributions in recoil momenta and their energy distributions for the high energy non-relativistic double photoionization of helium caused by the quasifree mechanism of the process. The distributions obtain local maxima at…
We present accurate time-dependent ab initio calculations on fully differential and total integrated (generalized) cross sections for the nonsequential two-photon double ionization of helium at photon energies from 40 to 54 eV. Our…
In this article we present triple differential cross sections for equal energy sharing kinematics for double photoionization of the helium atom at 20 and 40eV above threshold in the framework of the hyperspherical partial wave theory. This…
Multiphoton ionization provides a clear window into the nature of electron correlations in the helium atom. In the present study, the final state energy range extends up to the region near the $N=2$ and $N=3$ ionization thresholds, where…
In a previous publication, procedures were proposed for unambiguously extracting amplitudes for single and double ionization from a time-dependent wavepacket by effectively propagating for an infinite time following a radiation pulse. Here…
The two-photon decay of heavy, helium-like ions is investigated based on second-order perturbation theory and Dirac's relativistic equation. Special attention has been paid to the angular emission of the two photons, i.e., how the angular…
We calculate the photo-ionization cross-section from the ground state of the helium atom, using the complex rotation method and diagonalization of sparse matrices. This produces directly the positions and widths of the doubly excited 1Po…
A theoretical study of the polarization entanglement of two photons emitted in the decay of metastable ionic states is performed within the framework of density matrix theory and second-order perturbative approach. Particular attention is…
Few-photon induced breakup of helium is studied using a newly developed ab initio numerical framework for solving the six-dimensional time-dependent Schroedinger equation. We present details of the method and calculate (generalized) cross…