  We discuss the production of ultracold molecules in their electronic ground
state by photoassociation employing electronically excited states with ion-pair
character and strong spin-orbit interaction. A short photoassociation laser
pulse drives a non-resonant three-photon transition for alkali atoms colliding
in their lowest triplet state. The excited state wave packet is transferred to
the ground electronic state by a second laser pulse, driving a resonant
two-photon transition. After analyzing the transition matrix elements governing
the stabilization step, we discuss the efficiency of population transfer using
transform-limited and linearly chirped laser pulses. Finally, we employ optimal
control theory to find the most efficient stabilization pathways. We find that
the stabilization efficiency can be increased by one and two orders of
magnitude for linearly chirped and optimally shaped laser pulses, respectively.
