Classical analysis of Coulomb effects in strong-field ionization of H2+ by intense circularly polarized laser fields

We analyze the distortion of the molecular frame photoelectron angular distributions of H-2(+) ionized by a strong, circularly polarized infrared laser field using classical trajectory Monte Carlo simulations. We find that the nonisotropic field of the molecular ion rotates the final electron momenta. The degree of distortion from the strong-field approximation's predictions is thereby sensitive to the field strength and the internuclear distance but, counterintuitively, does not necessarily decrease for high field strengths. Furthermore, the distortion also depends crucially on the initial momentum of the classical electron after tunneling, while the exact shape of the ionization rate seems to be less important. A trajectory analysis within our simple model allows us to interpret recent experimental results.