Correlation splitting

Shull, H., and Lowdin, P.-O., J. Chem. Phys. 25, 1035, Correlation splitting in helium-like ions. ... 

First serious practice in correlating splitting patterns and chemical shifts. 

For a clear distinction whether band multiplets are due to correlation splitting or caused by crystallographically different H2O molecules in the lattice, the isotope dilution technique (see Sect. 2.6) is recommended. In the former case the multiplets coalesce into a singlet on decoupling of the vibrations, in the latter one the multiplets remain upon deuteration. 

Crystallographic results show that there are strong intermolecular interactions between the oxygen atom and one of the halogens in both solid POCI3 and solid POBrg, but similar interactions in PSBrj are absent. These results are compared with the extent of correlation splitting in the i.r. spectra. 

Fig. 4.16 The effect of temperature on the correlation splitting of the Raman-active CH2-twisting doublet of polyethylene (a) the sample at room temperature (b) the sample at —196°C (c) the sample at —196°C with increased spectral resolution and expanded...

Figure 2.9 Qualitative energy levels for a atom under Russell-Saunders coupling. Electron correlation splits the energy levels of states with different (Z., S) spin-orbit coupling further splits levels with different J.

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