Comparative study of electron vortices in photoionization of molecules and atoms by counter-rotating circularly polarized laser pulses

Abstract

We comparatively study the effect of orbital symmetry on vortex patterns in photoelectron momentum distributions (PMDs) of perfectly aligned H2 and N2 molecules and their companion atom Ar exposed to a pair of delayed counter-rotating circularly polarized lasers by numerically solving the two-dimensional time-dependent Schrödinger equation. We show that vortex patterns in PMDs strongly depend on the orbital symmetry of atoms and molecules, and numbers of spiral arms in PMDs of N2, H2, and Ar are quite different even though they have nearly identical ionization potentials. We also confirm that vortex structures in PMDs of the highest occupied molecular orbit (HOMO)-2 for N2 are quite different from those of the HOMO but similar to those of Ar. Furthermore, vortex patterns in PMDs of molecules are also sensitive to internuclear distances and alignment angles, which provides more possibilities for controlling the coherent interference of electronic wave packets in comparison with atoms.

Electron vortex generations in photoionization of hydrogen atoms by circularly-polarized chirped attosecond pulses

“…The generation of vortex-shaped photoelectron wave packets in the photoionization of helium atoms [13,28] and hydrogen molecular ions [29] has been proposed by employing timedelayed counter-rotating circularly polarized attosecond pulses. In addition to the time delay, researchers have also explored the control of other laser parameters, such as the carrier-envelope phase (CEP) [17,27], relative optical phase [25,30], polarization state [13,23,28,31,32], orbital symmetry [33,34], and chirp [35]. Moreover, vortices have not only been observed in photoionization but also in photodissociation [29] and photodetachment [36,37].…”

Imagining density distribution of molecular orbitals in IR+XUV co-rotating circular laser fields by frequency-domain theory

“…In recent years, the CRTC fields and corotating twocolor (CoRTC) fields have been used to control nonsequential double ionization (NSDI) [27,28], investigate nonadiabatic offsets of the initial electron momentum distribution in strongfield tunnel ionization [29], and observe experimentally subcycle interference structures in the photoelectron momentum distributions (PEMDs) [30,31], etc. Additionally, it has been shown that PEMDs generated by bicircular laser fields carry the information about the molecular orientation and structure [32][33][34].…”