Luminescence spectra of the uranyl ion in two geometrically similar coordination environments. Uranyl nitrate hexahydrate and di-. mu. -aquo-bis(dioxobis(nitrato)uranium(VI)) diimidazole

Journal Article · Thu Oct 02 00:00:00 EDT 1980 · J. Phys. Chem.; (United States)

DOI:https://doi.org/10.1021/j100457a031· OSTI ID:6873055

Brittain, H G ^[1]; Perry, D L

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1. Seton Hall Univ., South Orange, NJ

The luminescence spectra of the uranyl ion have been obtained at room and liquid-nitrogen temperatures in the crystal hosts of uranyl nitrate hexahydrate (UNH) and di-..mu..-aquo-bis(dioxobis(nitrato)uranium(VI)) diimidazole (UNI). In both coordination spheres, the uranyl ion lies at the center of similar, distorted coordination hexagons consisting of two bidentate nitrate groups and two water molecules; the only difference in the coordination geometries is that the water molecules are terminal in the UNH complex and bridging in the UNI complex. The uranium-uranium bond distance in the UNI complex is 3.93 A. At room temperature, the emission spectra of the two compounds are essentially identical, but significant differences appear upon cooling to 77 K. Vibronic structure is observed in the crystal of the UNI complex but not in the crystal of uranyl nitrate hexahydrate; this implies that the geometry of the uranyl ion in the two excited states is somewhat different. An energy level sequence is presented in which the various emission lines arise from a slightly split excited state (splitting approximately 80 to 85 cm/sup -1/) to several vibrational levels of the ground electronic manifold. The energy spacing of the ground vibrational levels (approximately 860 cm/sup -1/) was found to vary when changing crystal systems.

• OSTI ID: 6873055
• Journal Information: J. Phys. Chem.; (United States), Vol. 84:20
• Country of Publication: United States
• Language: English

Related Subjects

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
IMIDAZOLES
ENERGY LEVELS
VIBRATIONAL STATES
URANYL COMPLEXES
URANYL NITRATES
HYDRATES
LOW TEMPERATURE
LUMINESCENCE
MEDIUM TEMPERATURE
ACTINIDE COMPLEXES
ACTINIDE COMPOUNDS
AZOLES
COMPLEXES
EXCITED STATES
HETEROCYCLIC COMPOUNDS
NITRATES
NITROGEN COMPOUNDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXYGEN COMPOUNDS
URANIUM COMPLEXES
URANIUM COMPOUNDS
URANYL COMPOUNDS
400702* - Radiochemistry & Nuclear Chemistry- Properties of Radioactive Materials