Probing autoionizing states of molecular oxygen with XUV transient absorption: Electronic-symmetry-dependent line shapes and laser-induced modifications

摘要

We used extreme ultraviolet (XUV) transient absorption spectroscopy to study the autoionizing Rydberg states of oxygen in an electronically- and vibrationally-resolved fashion.XUVpulse initiates molecular polarization and near-infrared pulse perturbs its evolution. Transient absorption spectra show positive optical-density (OD) change in the case of nsσ_g and ndπ_g autoionizing states of oxygen and negative OD change for ndσ_g states.Multiconfiguration time-dependent Hartree-Fock (MCTDHF) calculations are used to simulate the transient absorption and the resulting spectra and temporal evolution agree with experimental observations. We model the effect of nearinfrared perturbation on molecular polarization and find that the laser-induced phase-shift model agrees with the experimental andMCTDHF results, while the laser-induced attenuation model does not.We relate the electronicstate- symmetry-dependent sign of the OD change to the Fano parameters of the static absorption line shapes.