Photoelectron asymmetries and puzzling molecular dynamics in the two-color dissociative photoionization of molecular hydrogen by synchrotron extreme ultraviolet and near infrared laser pulses.

The coupled electronic and nuclear dynamics in the dissociation of the simplest molecular ion, H₂⁺ are investigated by electron-ion coincidence momentum imaging experiments employing synchrotron extreme ultraviolet (SXUV) and delayed near infrared (NIR) laser pulses of moderate intensity (peak intensity I ≈ 10¹¹ W/cm²). Using first principles time-dependent theory we show that the SXUV photoionization populates vibrationally excited H₂⁺ (X ²Σ_g⁺_, ν=6 to ν=15), and we find evidence for asymmetry imprinted in the molecular frame of H₂⁺ by the NIR laser pulses due to charge-resonance enhanced dissociation. The experimental and computational results illuminate the various roles of charge resonance enhanced dissociation, bond-softening and light-induced conical intersections. The molecular frame photoelectron angular distributions (MFPADs) exhibit asymmetries that depend on the H₂⁺ vibrational level and the SXUV-NIR delays, revealing the mechanisms by which the NIR field couples the bound and dissociative nuclear wavefunctions.