Low-Temperature Absorption Spectrum of Uranium(3+) Formate Energy Level Scheme of Uranium(3+)

The absorption spectrum of thin films of U(HCOO)3 was measured at 298, 77, and 4°K in the range 4000–24 000 cm−1. Electrostatic, spin—orbit, and configuration-interaction parameters were obtained by least-squares fitting to 12 observed levels for U(HCOO)3. The obtained parameter values (in cm−1) are: E1=2779, E2=14.1, E3=271.6, ζ5f=1656.4, α=17.5, β = −479, γ=1000. A good agreement with experiment is observed for all calculated levels and a number of new assignments of excited levels of U(3+) are proposed. Intensity calculations were carried out and considered in the problem of level assignment.