for his help in obtaining and interpreting the n.m.r. spectra. We also extend thanks to Mr. J. W. Coryell, who aided us in the cryoscopic and surface tension measurements.

The fluorescence spectra of europium and terbium /3-diketone chelates are modified significantly on changing substituents in the organic ligand. The relative intensity, spectral distribution, shifting, and splitting of the fluorescence lines are discussed in relation to the nature of substituents, their position, molecular configuration, and the over-all intramolecular energy transfer.

No abstract

No abstract

No abstract