  We study bound states of two fermions with opposite spins in an extended
Hubbard chain. The particles interact when located both on a site or on
adjacent sites. We find three different types of bound states. Type U is
predominantly formed of basis states with both fermions on the same site, while
two states of type V originate from both fermions occupying neighbouring sites.
Type U, and one of the states from type V, are symmetric with respect to spin
flips. The remaining one from type V is antisymmetric. V-states are
characterized by a diverging localization length below some critical wave
number. All bound states become compact for wave numbers at the edge of the
Brilloin zone.
