J. Phys. II France
Volume 5, Numéro 6, June 1995
Page(s) 755 - 764
DOI: 10.1051/jp2:1995164
J. Phys. II France 5 (1995) 755-764

Parametrization of 5f-5f Transition Probabilities Between Stark Levels of U 3+ in LiYF 4

E. Simoni1, M. Louis1, S. Hubert1 and M.F. Reid2

1  Institut de Physique Nucléaire, Groupe de Radiochimie, B.P. N° 1, 91406 Orsay Cedex, France
2  University of Canterbury, Christchurch, New Zealand

(Received 21 December 1994, received in final form 21 February 1995, accepted 1 March 1995)

In order to simulate intensities of the 5f-5f transitions of U 3+ in LiYF 4, we applied the Judd-Ofelt theory. Because of the large crystal-field splitting of the J-multiplets in the actinides, a set of phenomenological intensity parameters $B_{\lambda kq}$ is introduced to describe the transition probabilities between the crystal-field sublevels of U 3+. The intensities of the absorption transitions between the crystal field levels calculated and a set of six phenomenological intensity parameters give a rather good simulation of the experimental intensities, and the applicability of the Judd-Ofelt theory is discussed for the 5f $\rightarrow$ 5f transitions of the actinides. From these values, the oscillator strengths between the excited states involved in the laser transition $^4{\rm I}_{11/2}\rightarrow ^4{\rm I}_{9/2}$ are calculated and the corresponding radiative lifetime is compared to the experimental one. Moreover, a comparison between the actinide ion U 3+ (5f 3) and the lanthanide ions Nd 3+ (4f 3) and Er 3+ (4f 11) in LiYF 4 is made.

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