Slater-Condon-Shortley parameters

As with ligand-field absorption spectra, the Nephelauxetic effect [41, 42] will also impact L-edge XAS data. For L-edge spectra, the effect of a reduction in interelectron repulsion is also to reduce the ffee-ion state splitting and make the spectra somewhat more orbital like. This is demonstrated by the sequence of simulated low-spin Fe(III) L-edge X-ray absorption spectra shown in Fig. 13, where the e - e repulsion is reduced systematically from [i = 100% to 60%. This starts from 80% of the Hartree-Fock calculated values of the Slater Condon Shortley parameters for e - e repulsion. 

Slater-Condon-Shortley parameters of interelectronic repulsion photon energy ionization energy... 

In further refinement, one could consider additional pressure effects on C for some ions. (One might expect that the Slater-Condon-Shortley parameter would be more affected by pressure than F. ) Alternatively one might assume with Stout that the higher energy Cg) levels are more spread out by the crystal field than the 2 levels. One could then calculate the covalency parameter e for these as a function of pressure. 

The energy levels of the free Cr3+-ion (d ) are quite well known (4). A quantitative description with the Slater-Condon-Shortley method (5) using the Racah-parameters B and C ) and the L—S-coupling parameter A does not lead to a satisfactory agreement between theory and experiment this can be achieved only by assuming different C/R-ratios for different doublet-levels (Table 1). The depression of the P-level is especially remarkable. The deviations from the three-parameter theory are less pronounced for Ni + or Co + (2), for example. 

Once it was realized that there is an almost invariant ratio between the parameters of interelectronic repulsion in the f shell, both in the Slater-Condon-Shortley parametrization 1 0.75 0.5, and in the treatment of Racah... 

Several of the numbers in eq. (15) may readily be uncertain by a factor of two, but for our purpose, the most important feature is Xz close to a half. This qualitative result pervades ligand field calculations, and it is almost surprising that Hartree-Fock radial 4f functions only overestimate the parameters of interelectronic repulsion by 30-40%, and it is close to unbelievable that the relative distances of terms in Ln(III) are better described by Slater-Condon-Shortley-Racah parameters than d and p in monatomic entities. 

The attraction of the second spectrum of lanthanum for atomic spectroscopists has been mentioned in section 2.1. The analyses of the two-electron configurations 4f5d and 4f carried out by Condon and Shortley (1931) achieved great importance by being the only lanthanide spectrum described in detail in their subsequent monograph (Condon and Shortley 1935). The least-squares fits to the experimental data provided by Russell and Meggers (1932) yielded Slater parameters given (in cm ) by... 

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