Lanthanum crystal field parameters

The absorption spectrum of Bk(III) in a lanthanum chloride host matrix at 77 K was first obtained in 1964 (102). A prediction of the energy level structure of Bk(III) was made by others the same year (103). Extensive, low-temperature spectroscopic studies of BkCl3 showed the absence of transitions to excited J = 0 and J = 1 states (104, 105). This provided good evidence for a fi = 0 ground level for Bk(III), consistent with that of Tb(III)-LaCl3 (106). Experimental and theoretical studies of the crystal field parameters of Bk(III) in a LaCl3 host lattice have also been reported (107). 

The analysis of crystal-field components has remained at the single-particle level introduced by Bethe ( ). Crystal-field parameters for the actinide ions in lanthanum trichloride are shown in Table III. They are approximately twice as large as the values found for the lanthanides. Although the values... 

Table III. Crystal-Field Parameters for Trivalent Actinide Ions in Lanthanum Trichloride. Units are cm"-1-.

The experimental results for the various lanthanide ions diluted in host crystals of lanthanum and/or yttrium ethylsulfate are summarized in table 18.27. Historically, the ethylsulfates were the first class of compounds on which ESR measurements of the lanthanide ions were made. As noted in section 3.2.2, the point symmetry at the lanthanide site is Csh, and just four parameters are required to characterize the crystalline electric field (CEF). These are, in notation of eq. (18.109), B , B , and Bt In consequence of the axial... 

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