Asymmetry of the photoelectron momentum distribution from molecular ionization in elliptically polarized laser pulses

We theoretically study the photoelectron momentum distributions (PMDs) of ${{\mathrm{H}}_{2}}^{+}$ in elliptically polarized laser fields by numerically solving the time-dependent Schr\"odinger equation. Depending on the internuclear distance of ${{\mathrm{H}}_{2}}^{+}$, the PMDs reveal different asymmetries with respect to the major and minor axes of the laser ellipse. At an internuclear distance corresponding to the enhanced ionization region, the asymmetry of the PMDs is opposite to that of the companion atom. We attribute this phenomenon to the effect of the internal scattered electrons, which are mainly released at an earlier ionization moment with respect to the field maximum within each half cycle. We further show that the asymmetry of the PMDs in the elliptical laser fields can be used to identify the instant when the electron wave packet is released from the molecule.