Spectroscopic evaluation of Tb(III) chelates for potential utility as diagnostic markers

Lanthanide spectroscopy was exhaustively studied in the early 19th Century. It was quickly learned that the fluorescence of the molecules was superb; however, the absorption cross section of the molecule was low and interest in the molecules subsided. The interest in Lanthanides resurfaced in the 1980's when chelation of a lanthanide central ion into an organic cage solved the absorption problem. The most striking features of the Lanthanide chelates were the enormous Stoke's Shift and long luminescence lifetimes. These two features enabled the investigator to sensitively probe for the solute because the signal was spectrally and temporally shifted from background noise.