COMBINED ORTHOGONAL FIT OF FINE AND HYPERFINE-STRUCTURE

The independence of orthogonal operators is used to extend the Hamilto nian with hyperfine structure operators. The interaction strength of e lectrostatic, fine and hyperfine operators may then be determined in a single least-squares fit to the observed energies. To illustrate the framework, we studied the transition array 5d(9)6p --> 5d(9)6s of Bi V I. This spectrum exhibits a large hyperfine structure and is highly re lativistic, but polarization effects are small. A Dirac-Fock calculati on turns out to be successful and even shows the superiority of an ext ended nucleus over a point nucleus description.