Optical and Magnetic Resonance Spectra of Inorganic Molecular Crystals-Uranium Borohydride (U(BH4)4) in Hafnium Borohydride (HF(BH4)4)

摘要

The electronic absorption and EPR spectra of U(BH4)4 as a guest in Hf(BH4)4 host crystals are reported. Optical spectra, from the charge transfer or f-to-d cutoff at ca. 2900A to the low energy limit due to host molecular vibrations at ca. 2.0 micrometer, have been obtained at 300, 77, and 2 K for mixed crystals of U(BH4(4Hf(BH4)4 and U(BD4)4/Hf(BD4)4. From temperature effects, deuteration shifts, and intensity patterns, over 20 forced electric dipole crystal field electronic origins have been identified. Several molecular vibrations have been identified built on these origins and based on physically reasonable arguments, are tentatively associated with specific vibrational symmetries and motions of M(BH4)4 type molecules. Calculations, based on a free ion and cubic crystal field parameterized Hamiltonian, are employed to assign electronic origins. Implications of these crystal field and vibrational analyses for actinide spectroscopy are discussed.