On the Absorption Spectra of Complex Ions II

Abstract

The secular determinants obtained in the previous paper are solved for the energy levels which are important in the absorption spectra of the normal complex ions, leaving the crystalline field strength as a parameter. The values of B and C (Racah's parameters) there needed are determined from the observed spectra of free ions or in some cases by extrapolation. The f -values of the transitions which connect the energy levels calculated are estimated and compared with the observed intensities. The difference of the spectral width among absorption bands and lines is also considered using the energy diagram obtained. Following the assignments determined by the above considerations, the calculated positions of lines and bands are rather in good agreement with the experimental data in divalent ions [MX 6 ] 2+ (M=Cr, Mn, Fe, Co, Ni), when we adjust the crystalline field parameter D q suitably. In trivalent ions [MX 6 ] 3+ (M=Ti, V, Cr, Mn, Fe), it is necessary besides the adjustment of D q to use smaller values of B and C than those of the free ions to obtain better agreement with experiments. The values of D q thus determined are of reasonable magnitude close to those obtained in other ways. The decrease of B and C compared with those of the free ions might be connected with the recent Stevens' suggestion. It is interesting that, though the agreement is poor about, [Co(H 2 O) 6 ] 3+ and [Co(NH 3 ) 6 ] 3+ whose bindings are usually considered covalent, the qualitative explanation of their spectra is found possible in the crystalline field approximation.