Optical absorption spectrum of dilute U4+ impurities in incommensurate ThBr4 : lineshape analysis

P. Delamoye (1) , R. Currat (2)

1 IPNO - Institut de Physique Nucléaire d'Orsay
2 ILL - Institut Laue-Langevin

Crystal-field transitions associated with U4+ impurities diluted in ThBr4 give rise to broad absorption bands characterized by edge singularities. We show that the experimental spectra are consistent with the known occurrence of a sinusoidal distortion which modulates the Br- ion equilibrium positions, thus reducing the actinide site-symmetry from D2d to D2. The observation of spectral singularities corresponding to D2d-sites is interpreted as resulting from the partial pinning of the incommensurate modulation by the U4+ impurities.

Mots clés: crystal field interactions; impurity and defect absorption spectra of inorganic solids; spectral line breadth; thorium compounds; uranium; optical absorption spectrum; crystal field transitions; dilute U sup 4+ impurities; incommensurate ThBr sub 4; lineshape analysis; edge singularities; sinusoidal distortion; Br sup ion equilibrium positions; actinide site symmetry; spectral singularities; partial pinning; incommensurate modulation

Domaines: Articles anciens; Chimie-Physique [physics.chem-ph]

P. Delamoye, R. Currat. Optical absorption spectrum of dilute U4+ impurities in incommensurate ThBr4 : lineshape analysis. Journal de Physique Lettres, 1982, 43 (17), pp.655-663. ⟨10.1051/jphyslet:019820043017065500⟩. ⟨jpa-00232107⟩