K. Rajnak

Uranium five (U v), the 1 S 0 level, and a parametric analysis of the 5f 2 configuration

The 1S0 level of the 5f2 configuration of U v has been found at 43 613.58 ± 0.1 cm−1. A parametric fit of the 13 levels of the 5f2 configuration gives an rms deviation of 9.8 cm−1 with F2 = 51 938 ± 39, F4 = 42 708 ± 100, F6 = 27 748 ± 68, α = 35.5 ± 0.4, β = −664 ± 25, γ = 744 ± 26, ζ = 1968 ± 2, P2 = 573 ± 66, P4 = 524 ± 144, and P6 = 1173 ± 321, all in inverse centimeters.

ANALYSIS OF THE OPTICAL SPECTRUM OF Np(BD4)4 DILUTED IN Zr(BD4)4 AND THE MAGNETIC PROPERTIES OF Np(BH4)4 AND Np(BH3CH3)4

The optical spectrum of Np(BD4)4/Zr(BD4)4 is reported and analyzed. The parameter values obtained are consistent with those for U(BD4)4/Hf(BD4)4. A total of 46 levels were fit with σ=84 cm−1. EPR data on Np(BD4)4/Zr(BD4)4 and Np(BH3CH3)4/Zr(BH3CH3)4 and the magnetic susceptibility of Np(BH3CH3)4 are reported. They could be fit with the eigenvectors from the optical analysis only by the inclusion of orbital reduction factors k=0.885 for Np(BD4)4 and 0.862 for Np(BH3CH3)4. These values indicate greater covalency for the methylborohydride.

Energy Levels of Pu3+ in Lanthanum Trichloride

Polarized absorbtion spectra and some Zeeman effect measurements in the region of 20 000–32 000 cm−1 are reported for Pu3+ in LaCl3. A total of 25 J levels was fitted with an rms deviation of 100 cm−1 with the parameters values E0=14 930.5, E1=3726.7, E2=14.99, E3=350.18, ξ=2260.2, α=36.5, β=−1171. The large values of α and β indicate that configuration‐interaction effects cannot be neglected in an analysis of the spectra of the higher actinides.

Optical and magnetic properties of uranium borohydride and tetrakismethylborohydride

The U(BD4)4/Hf(BD4)4 optical spectrum reported by Bernstein and Keiderling has been reanalyzed. All 19 allowed transitions have been identified. The crystal field is ∼2.5 times as strong as that of  U4+/ThBr4, but the values of the Fk and ζ parameters are nearly the same. The magnetic susceptibility of the structurally related molecule U(BH3CH3)4 has been measured from 2–330 K. Using the eigenvectors from the optical analysis, the magnetic data can be fit with an orbital reduction factor k=0.85. For U(BD4)4/Hf(BD4)4 k=ζ/ζfree ion=0.91.

Calculation of the crystal field splittings of Sm3+ levels in LaCl3 with inclusion of J mixing

A complete diagonalization of the matrices for the electrostatic, spin‐orbit, and crystal field interactions for Sm3+ in LaCl3 has been carried out using a truncated set of basis vectors containing 42 of the 73 LS states. This diagonalization allowed many new assignments to be made. Corrections of some of the centers of gravity previously used in a fit of free ion parameters was also possible. The newly obtained free ion parameters are more in accord with the trends for the other lanthanide ions in LaCl3. They reduce the rms deviation from 119 to 54 cm−1. The parameters (in cm−1)used in the final diagonalization are E1=5465.27 ± 17.21, E2=25.40 ± 0.39, E3=547.62 ± 1.65, ζ=1153.8 ± 8.9, a=24.29 ± 1.98, β=−795.72 ± 98.4, γ=800, B02=161.70, B04=−182.00, B06=−710.24, B66=448.14.