The relativistic impulse approximation is used to generate scalar and vector optical potentials for p¯ atoms which are used to investigate spin and isospin dependent effects. These potentials describe the isospin dependence of shifts and widths for the oxygen isotopes very well. Definite predictions are made for the spin-orbit dependence of the shifts and widths in Yb and Th, for which experimental results are becoming available. There appear to be significant discrepancies. The importance of including the electromagnetic spin-orbit interaction and the long tails of weakly bound nucleons is pointed out.

• Received 25 September 1986

DOI:https://doi.org/10.1103/PhysRevC.35.1410