Tetrad effect solvent extraction

It should be pointed out that not all the ions discussed here are affected by the outer fields. In fact, lanthanide ions may be affected by solvents or coordination fields in chemical reactions. For example, E and E will change because of the coordination effect of water or organic molecules in an extraction. In addition, the amount of change would be different in different media. The tetrad effect would thus be different in different systems. The tetrad effect not only relates to the electronic configurations of lanthanide elements but is also affected by the surrounding conditions. Currently it is still not possible to predict the tetrad effect or to calculate it quantitatively. Tetrad effect theory still needs to be improved and further data need to be accumulated. 

This tetrad effect was first reported by D. F. Peppard and G. W. Mason in the Argonne National Laboratory s Physical Research Monthly Report for September, 1968. A note has been submitted by D. F. Peppard, G. W. Mason, and S. Lewey to J. Inorg. Nucl. Chem. to be followed by a comprehensive report. This effect is also reported by Peppard, Mason, and Lewey in the Proceedings of the Fifth International Conference on Solvent Extraction Chemistry (5th ICSEC) held in Jerusalem, Israel, September 16-18,1968. 

Kawabe, I. and Masuda, A. (2001) The original examples of lanthanide tetrad effect in solvent extraction a new interpretation compatible with recent progress in REE geochemistry. Geochem. /., 35, 215-224. 

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