Abstract
The Zeeman spectrum has been observed, in the high-field limit, of the photoluminescence emission line due to the recombination of excitons bound to isoelectronic bismuth centres in indium phosphide. It is found that the zero-field exchange splitting is less than 0.2 meV. Measurements of spectral anisotropy confirm the point defect model for this centre. Relevant splitting factors are K=0.72+or-0.05, L=-0.066+or-0.01 (hole), and geff=1.15+or-0.05 (electron).