Monitoring coherent electron wave packet excitation dynamics by two-color attosecond laser pulses

We propose a method to monitor coherent electron wave packet (CEWP) excitation dynamics with two-color attosecond laser pulses. Simulations are performed on aligned H₂⁺ by numerically solving the three-dimensional time-dependent Schrödinger equation with combinations of a resonant linearly polarized λ_l= 100/70 nm pump pulse and a circularly polarized λ_c=5 nm attosecond probe pulse. It is found that time dependent diffraction patterns in molecular frame photoelectron angular distributions (MFPADs) produced by the circular probe pulse exhibit sensitivity to the molecular alignments and time-dependent geometry of the CEWPs during and after the coherent excitation between the ground and excited states induced by the linear pump pulse. The time dependent MFPADs are described by an ultrafast diffraction model for the ionization of the bound CEWPs.