Two-center Effects in One-photon Single Ionization of H$_2^+$, H$_2$ and Li$_2^+$ with Circularly Polarized Light*

Circularly polarized one-photon single ionization of H$_2^+$ and H$_2$ with energies of a few hundred eV and of Li$_2^+$ with tens of eV allows the investigation of two-center interference effects due to confinement and double-slit diffraction. Accurate theoretical results of Exterior Complex Scaling calculations are presented showing that the angular distributions for circularly polarized light are very similar to those obtained by averaging the corresponding angular distributions for parallel and perpendicular linearly polarized light, implying that coherence between $\Pi_u$ and $\Sigma_u^+$ amplitudes is unimportant in determining those distributions. Consequently, confinement and double-slit effects observed in the case of linear polarization are also present in the case of circularly polarized light. For Li$_2^+$, because the effects appear at electron energies that are significantly lower, the results are more sensitive to details of the molecular potential.