Absorption and Circular Dichroism Spectra of Bi12SiO20<Nd> Crystals

The absorption and circular dichroism spectra of Nd-doped Bi₁₂SiO₂₀ crystals were measured in the range 10000 to 20000 cm^–1. The spectra showed electronic transitions related to only one type of Nd-related center: Nd substituting for Bi in position with symmetry C ₁. The bands due to the transitions from the first Stark component of the ground state to Stark components of excites states (⁴ I _9/2 ⁴ G _5/2, ⁴ I _9/2 ² G _7/2, and ⁴ I _9/2 ⁴ G _7/2) were analyzed in detail. The dipole strength D _0k , rotatory power R _0k , and anisotropy factor G _0k of these transitions were calculated. The intensities of transitions to Stark components were shown to vary by more than one order of magnitude within an excited-state multiplet. The anisotropy factors of the ⁴ I _9/2 ² G _7/2 and ⁴ I _9/2 ⁴ G _7/2 transitions, allowed in the magnetic dipole approximation, are, on the average, larger than that of the ⁴ I _9/2 ⁴ G _5/2 transition, which points to a significant contribution of the magnetic moment (<>²) to the total intensity of the transition.