  We present a theoretical study of bound-free electron-positron pair
production in the interaction of $\gamma$-rays with bare ions. Special
attention is paid to the longitudinal polarization of both the emitted
positrons and the produced hydrogen-like ions. To evaluate this polarization we
employed exact solutions of the relativistic Dirac equation and treat the
electron-photon coupling within the framework of first-order perturbation
theory. Detailed calculations have been performed for both, low- and high-Z
ions and for a wide range of photon energies. The results of these calculations
suggest that bound-free pair production can be a source of strongly polarized
positrons and ions.
