By using segmented solid state X-ray detectors and applying X-ray/charge-state selective particle coincidences, the ionic structures of 83Bi 82+ and 83Bi 81+ have been studied separately at 82 MeV/u under single collision conditions. The high granularity of the Ge(i) X-ray detectors used allowed a partial Doppler correction for the X-ray events while maintaining a large total solid angle. An absoluute precision of K-transition energies of 10 −3 is feasible; the relative accuracy is better than 30 eV. The experimental values compare very well with the theoretical transition energies in H- and He-like Bi ions.