Energy Levels of Single-Crystal Erbium Oxide

Abstract

The absorption spectra of large single crystals of Er₂O₃ observed at 10°, 80°, and 290°K were analyzed in the 2200–10 000‐Å wavelength region. Over 600 transitions from all eight crystalline Stark levels of the ground ⁴I_15/2 state to over 30 excited J manifolds of the Er³⁺ ion in C₂ sites were assigned. In thick crystals, evidence of vibronic spectra of ions in C₂ and S₆ sites was observed for seven J manifolds. The observed spectrum is compared with a calculation which includes configuration‐interaction effects on all expected ``free‐ion'' energy levels of Er³⁺ between the ground state and 44 000 cm⁻¹. The parameters E¹=6844, E²=32.04, E³=635, ζ=2354, α=12.2, β=−590, and Y(22, 1)=−4180 cm⁻¹ yield an rms deviation of 73 cm⁻¹ between observed and calculated energy levels. The significance of these parameters in comparison with those for Er³⁺ in other crystals is discussed.