Published online by Cambridge University Press: 15 November 2000
A detailed crystal-field analysis, based on the Racah' theory, was carried out for the so-called A, B and G1 isolated charge-compensation centers of Er3+ ion doped in CaF2 crystal. Three sets of crystal-field parameters were obtained by a least-squares fitting of the optical data of Er3+ ion diluted in epitaxial Ca1−xErxF2+x thin film. This theoretical analysis confirms the expected $C_{4\nu}$ site symmetry for the A center and the $C_{3\nu}$ site symmetry for the G1 center. For the B center, however, the site symmetry is not exactly $C_{3\nu}$ in contrast to what is believed.