Asymmetry of molecular frame photoelectron angular distributions in H2+ by intense two-color attosecond pulses: coherent excitation and charge migration effects

Molecular frame photoelectron angular distributions (MFPADs) are theoretically studied by intense two-color attosecond linearly polarized laser pulses. Simulations are performed on aligned H-2(+) from numerical solutions of corresponding time-dependent Schrodinger equations. Asymmetric MFPADs are produced by a time-delayed soft x-ray attosecond pulse in the presence of an extreme ultraviolet (XUV) pump pulse. We present the dependence of the asymmetry ratio Gamma of the MFPADs on the laser parameters of the pump-probe pulses. The asymmetry ratio Gamma varies with the time delay, illustrating the coherent superposition of electronic states. Altering the phase, intensity and duration of the pump pulse gives rise to a modulation of the asymmetry ratio Gamma as well. Moreover, the asymmetry of the MFPADs disappears in the case of long duration probe pulses, illustrating the coherent charge migration dynamics on the attosecond time scale.