Stark effect study of the 4f66s2 7 F 1, 2, 3, 4, 5, 6 levels of samarium using nonlinear level crossing technique

Abstract

Abstract. The nonlinear level crossing technique withparallel electric and magnetic fields was used to investigate the Stark effect of six levels of the ground multiplet 4f 66 s 2 7F in the Sm I-spectrum. The tensor polarizabitities were deduced from the level crossing signals. The variation of the tensor polarizabilities of the levels of the ground multiplet is well reproduced by the LS coupling approximation, which gives an average value of c~2(F ) = -0.88(6) kHz/(kV/cm) 2 for the six measured levels. The experimental results confirm the validity of the central field approximation in the ground configuration of Sm.

Tensor polarizabilities of the 4f 7(8 S)5d6s 2 9 D 2,3,4,5,6 levels in Gd I

“…So far, the ratio B(J)/ez(J) has been studied only for all the levels of the ground multiplet 4 f 6 6s 2 7F in Sm I [4]. The values found for this ratio in Sm show very good agreement, which indicates that the levels are all unperturbed to a good approximation.…”

“…Since Hte. is a tensor of rank two, (4) can be written in the form [4] --0~2(n/) gz/2= (ntll C z InIl> K,n ~2 (6) KnL is a function of n and I. Since the tensor polarizabilities of the investigated levels depend only on the polarizability of a single electron, the tensor polarizabilities of the fine structure levels are given through Table 2.…”

Tensor polarizabilities of the (nd+(n+1)s)3 2 D 3/2,5/2 levels in Sc I, Y I, La I and Lu I

“…The results do not show satisfactory agreement• This points to considerable perturbations in the ZD multiplets. These may be caused by mixing with higher electronic configurations [2]. The single configuration approach is also inconsistent with the observed hyperfine structure in Lu [12], La [11,22], Y [9] and Sc [23].…”

“…The signs of the experimental ~2(J) values were chosen equal to the calculated values. Provided the ground multiplet in the investigated elements can be understood on the basis of a single configuration model, in the central field model the relation between ~2 (J) and the hyperfine quadrupole coupling constant B(J) [2] (4) should then be a constant for all the levels of a configuration with only one open shell. Any deviation implies a breakdown of the central field model.…”

“…Previous mesurements include determinations of tensor polarizabilities of levels in the ground multiplets of the configurations 4f v5 d 6 s z in GdI [1] and 4f66s 2 in SmI [2], in order to test the central field model, and of the configuration 4f N 6s 2 in the rare-earth elements Pr I, Nd I [3], Sm I [2,4], Tb I, Dy I, Ho I, Er I, and Tm I [3], in order to study the dependence of the polarizability of the 4f electron with an increasing number of 4f electrons. These investigations have revealed tensor polarizabilities of levels of the ground multiplet for all the stable elements of the rare earth atoms with a ground configuration 4f N6S 2.…”