A variation of ELISA using one member of this group takes advantage of the 
A variation of ELISA using one member of this group takes advantage of the fact that their ions have millisecond luminescence lifetimes and is called DELFIA. Complexes of members of this group can be analyzed by Friere and Simas' Sparkle Model. DOTA is a chelating agent used to isolate members of this group. Members of this group exhibit very high spin-orbit coupling and paramagnetism, which is why one member is found in the most common MRI contrast agent. Members of this group tend to decrease ionic radius as their (*) mass increases, a phenomenon called their namesake contraction. These elements are the first to have occupied f orbitals, and Seaborg placed them above the actinides. For 10 points, name these elements which have atomic number from 57 to 71, shown underneath the periodic table.
A variation of ELISA using one member of this group takes advantage of the fact that their ions have millisecond luminescence lifetimes and is called DELFIA.