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5f(3) - 5f(2)6d(1) absorption spectrum analysis of U3+-SrCl2

机译:U3 + -SrCl2的5f(3)-> 5f(2)6d(1)吸收光谱分析

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The 5f(3) -> 5f(2)6d(1) absorption spectra of the U3+ ions incorporated in SrCl2 single crystals were recorded at 4.2 K in the 15 000-50 000 cm(-1) I spectral range. From an analysis of the vibronic structure, 32 zero-phonon lines corresponding to transitions from the 4 I-4(9/2) ground multiplet of the 5f(3) configuration to the 5f(2)6d(e(g))(1) excited levels were assigned. A theoretical model proposed by Reid et al. (Reid, H. F.; van Pieterson, L.; Wegh, R. T.; Meijerink, A. Phys. Rev. B 2000, 62, 14744) that extends the established model for energy-level calculations of nf(N) states has been applied for analysis of the spectrum. The F-k(ff) (k = 2, 4), 5f xi(5f)(ff), B (4)(0)(ff) B (6)(0)(ff), F-k (fd) (k = 2, 4), and G(j)(fd) (j = 1, 3) Hamiltonian parameters were determined by a least 0 squares fitting of the calculated energies to the experimental data. A good overall agreement between the calculated and experimentally observed energy levels has been achieved, with the root-mean-square (rms) deviation equal to 95 cm(-1) for 32 fitted levels and 9 varied parameters. Adjusted values of F-k(ff) and xi(5f)(ff) parameters for the 5f(2) core electrons are closer to the values characteristic of the 5f(2) (U4+) configuration than to those of the 5f(3) (U3+) configuration. For the U3+ ion, the f-d Coulomb interaction parameters are significantly more reduced from the values calculated using Cowan's computer code than they are for lanthanide ions. Moreover, because of weaker f-d Coulomb interactions for the U3+ ion than for the isoelectronic Nd3+ lanthanide ion, the very simple model assuming the coupling of crystal-field levels of the 6d(1) electron with the lattice and the multiplet structure of the 5f(2) configuration may be employed for the qualitative description of the general structure of the U3+ ion f-d spectrum.
机译:掺入SrCl2单晶中的U3 +离子的5f(3)-> 5f(2)6d(1)吸收光谱在15,000-50 000 cm(-1)I光谱范围内以4.2 K记录。从振动学结构分析来看,32条零声子线对应于从5f(3)构型的4 I-4(9/2)地面多重态到5f(2)6d(e(g))( 1)分配兴奋水平。 Reid等人提出的理论模型。 (Reid,HF; van Pieterson,L .; Wegh,RT; Meijerink,A.Phys.Rev.B 2000,62,14744)扩展了已建立的用于nf(N)态能级计算的模型频谱分析。 Fk(ff)(k = 2,4),5f xi(5f)(ff),B(4)(0)(ff)B(6)(0)(ff),Fk(fd)(k = 2,4)和G(j)(fd)(j = 1,3)哈密顿量参数是通过将计算出的能量与实验数据进行至少0平方拟合确定的。对于32个拟合水平和9个变化的参数,已实现了在计算得出的能量水平和实验观察到的能量水平之间的良好总体协议,均方根(rms)偏差等于95 cm(-1)。 5f(2)核心电子的Fk(ff)和xi(5f)(ff)参数的调整值比5f(3)的调整值更接近5f(2)(U4 +)配置的特征值( U3 +)配置。对于U3 +离子,与使用镧系元素离子相比,使用Cowan计算机代码计算出的值明显降低了f-d库仑相互作用参数。此外,由于U3 +离子的fd库仑相互作用比等离子Nd3 +镧系元素离子弱,因此非常简单的模型假设6d(1)电子的晶体场能与晶格和5f(d)的多重结构耦合。 2)可以将配置用于U3 +离子fd光谱的一般结构的定性描述。

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