Crystal Field Splitting of Energy Levels of Thulium Ethylsulfate

The operator-equivalent method was employed to calculate the theoretical splitting of electronic energy levels 3P2, 1D2, 3F2, 3F3, 3F4, 1G4, and 3H6 in Tm(C2H5SO4)3·9H2O. Intermediate field corrections were made to α, β, and γ. A first-order perturbation treatment on Tm3+ (4f12) in C3h symmetry, using crystal-field parameters A20〈r2〉=13 cm—1, A40〈r4〉=—80 cm—1, A60〈r6〉=—32 cm—1, and A66〈r6〉=300 cm—1, predicts the position of the crystal quantum states in reasonable agreement with experiment.