Electronic Energy Levels of the Trivalent Lanthanide Aquo Ions. II. Gd3+

The free-ion energy level scheme of Gd3+ (aquo) to ∼52 000 cm−1 has been determined from the absorption spectrum of Gd3+ in dilute acid solution at 25°C. Several new absorption bands near 50 000 cm−1 have been ascribed to transitions from the ground state to components of the 6G multiplet. Energy level assignments were made on the basis of correlations between calculated and observed intensities. The resulting parameters were: E1 = 5761, E2 = 28.02, E3 = 582.0, ζ4f = 1450, α = 22.55, β = − 103.7, γ = 997.