Spiral nuclear momentum distribution for the dissociation of H2+ in a circularly polarized laser pulse

The dissociation of ${\mathrm{H}}_{2}{}^{+}$ in a circularly polarized laser pulse is numerically studied by simulating the time-dependent Schr\"odinger equation. After absorbing one or three photons, the nuclear wave packets carrying the angular momenta $\ensuremath{\hbar}$ and $3\ensuremath{\hbar}$ dissociate along the $2p{\ensuremath{\sigma}}_{u}$ state. Due to the broad initial kinetic-energy distribution of the superimposed nuclear vibrational states, the one-photon and three-photon dissociation pathways may end with the same kinetic energy. These coexisting dissociation pathways with same parities but different orbital angular momenta interfere with each other, resulting in the spiral nuclear momentum distribution in the laser polarization plane. The interference structure in the nuclear momentum distribution offers another freedom to identify the dissociation pathways of molecules in strong laser fields.