Buckingham-Stephens theory

In Stephens and Buckingham s seminal work the theories of MOR and MCD were developed together as real and imaginary... 

The Stephens and Buckingham theory shows that the paramagnetic shielding term (ap) is dependent on AE (the energy separation of the ground and excited states), Rh (the metal-hydrogen intemuclear distance), and k, the exponent of the d orbitals. The latter was taken to be constant over any particular row of transition metals. 

The aim of this chapter is to link the MCD theory to the lanthanide theory for crystal field splitting and transition intensity. We have based the theory on the very few papers that are due to pioneers in the field. These are for MCD (Buckingham and Stephens, 1966 Stephens, 1976), the book (Piepho and Schatz, 1983), for the lanthanide theory (Judd, 1962), the book (Wyboume, 1965) and for the experimental data (Camall, 1979). With humility we will also refer to our previous reviews (Gorller-Walrand and Binnemans, 1996, 1998) so that we remain as much as possible consistent with the quantities we use and their symbols. 

Ramsey theory [cf. (209), Ch. 7] developed by Kern and Lipscomb 188a) to eliminate the need for a knowledge of excited states. More recently, Buckingham and Stephens 42a) have shown that this treatment is inadequate in complexes where the panmu etic shielding contributes substantially to the total shielding. 

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