Asymmetry of molecular frame photoelectron angular distributions in ${{\rm{H}}}_{2}^{+}$ by intense two-color attosecond pulses: coherent excitation and charge migration effects

Abstract

Molecular frame photoelectron angular distributions (MFPADs) are theoretically studied by intense two-color attosecond linearly polarized laser pulses. Simulations are performed on aligned from numerical solutions of corresponding time-dependent Schrödinger equations. Asymmetric MFPADs are produced by a time-delayed soft x-ray attosecond pulse in the presence of an extreme ultraviolet (XUV) pump pulse. We present the dependence of the asymmetry ratio Γ of the MFPADs on the laser parameters of the pump-probe pulses. The asymmetry ratio Γ varies with the time delay, illustrating the coherent superposition of electronic states. Altering the phase, intensity and duration of the pump pulse gives rise to a modulation of the asymmetry ratio Γ as well. Moreover, the asymmetry of the MFPADs disappears in the case of long duration probe pulses, illustrating the coherent charge migration dynamics on the attosecond time scale.

Theoretical Study of Dynamic Stark-Induced π-Electron Rotations in Low-Symmetry Aromatic Ring Molecules beyond the Frozen Nuclear Approximation

“…Recently, the laser control of charge migrations in molecular systems has received considerable attention. − π-Electron rotations in aromatic ring molecules are typical examples of charge migrations. − Unidirectional π-electron rotations induced by lasers are expected to be a new source of strong ring currents and current-induced magnetic fluxes. ,,, Pioneering studies regarding the generation of coherent π-electron rotations in highly symmetric molecules with degenerate electronic states such as Mg porphyrin have been reported, , in which degenerate electronic states were coherently excited by circularly polarized ultraviolet (UV) lasers to induce π-electron rotations. The induction mechanism is the transfer of the photon angular momentum of the circularly polarized UV lasers to π-electrons, and its rotational direction depends on the left- or right-handed circular polarization of the applied lasers.…”

Molecular photoelectron momentum and angular distributions of N2 molecules by ultrashort attosecond laser pulses*

“…Attosecond electron co-herences have been tracked by photoelectron spectra in the xray region, which can allow one to monitor attosecond electron migration in atoms and molecules. [25] The photoelectron diffraction patterns in photoelectron spectra encode information about the molecular intrinsic properties including the orbital symmetry of the molecules. Some researchers investigated the dependence of the geometries and orbital structures on the photoelectron diffraction patterns of the N 2 and CO 2 molecules in few-cycle laser pulses.…”