Characterization of light-induced potentials in the strong-field dissociation of O₂⁺

We examine the imprints of light-induced potentials (LIPs) on the dissociation dynamics of O₂⁺ molecular ions, as observed in the angle-resolved fragment kinetic-energy-release (KER) spectra. By numerically solving the time-dependent Schrödinger equation within the Born-Oppenheimer approximation, we follow the vibrational and rotational motion of O₂⁺ molecular ions exposed to 800-nm, 40-fs laser pulses. For infrared (IR) peak intensities between 10¹³ and 10¹⁴ W/cm², we calculate angle-resolved KER spectra which reveal characteristic energy- and angle-dependent fringe structures. In general, we find that these fringes shift downward in energy as the molecular alignment angle θ relative to the IR-pulse polarization direction increases from 0 to π/2. The angle-dependent shifts in the KER fringes increase for higher IR-pulse peak intensities and follow the angle and peak-intensity dependence of the vibrational spectrum in the associated Floquet bond-hardening well, which is a manifestation of the transient O₂⁺ nuclear-probability trapping in the LIP during the dissociation process. Based on the analysis of the rovibrational dynamics of the dissociating molecular cation near the light-induced conical intersection (LICI) in the LIP surface at θ = π/2, we furthermore identify pertinent angle-dependent, LICI-related features in the KER spectra.

 

P. M. Abanador and U. Thumm, Phys. Rev. A 102, 053114 (2020).