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Optical spectroscopy and electron paramagnetic resonance of Pa/sup 4 +/ in ThBr/sub 4/ and ThCl/sub 4/ crystals

Journal Article · · J. Chem. Phys.; (United States)
OSTI ID:6482577
Polarized absorption and emission spectra of Pa/sup 4 +/ in ThCl/sub 4/ and ThBr/sub 4/ host matrices were recorded at different temperatures from 4.2 to 300 K in the infrared range. The seven crystal field levels of the 5f/sup 1/ configuration were determined from the optical data and fit by a parametrized model assuming a D/sub 2d/ site symmetry for the Pa/sup 4 +/ ion. However, at low temperature both matrices undergo a displacive phase transition and the low temperature structure is incommensurate and modulated. The halide position modulation reduces the site symmetry from D/sub 2d/ to D/sub 2/ for some Pa/sup 4 +/ ions, and, consequently, the shapes of some absorption bands are characterized by edge singularities. EPR experiments performed on these doped crystals provided g values for the ground state of Pa/sup 4 +/ which fit satisfactorily with the values calculated from the optical data.
Research Organization:
Laboratoire de Radiochimie, Institut de Physique Nucleaire, Universite de Paris-Sud, B.P. No. 1, 91406 Orsay Cedex, France
OSTI ID:
6482577
Journal Information:
J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 78:5; ISSN JCPSA
Country of Publication:
United States
Language:
English