Proton Relaxation in Paramagnetic Solutions

Those paramagnetic ions, such as Fe+++, Mn++, and Gd+++, which are in S spectroscopic states; and those ions, such as Cr+++ and Cu++, which are effectively in S states through complete quenching of the orbital component, have been shown to produce reciprocal proton relaxation times proportional to the square of the magnetic moment. Those ions such as Co++, Nd+++, and Dy+++, with strong spin-orbital coupling, have been shown to be, in equivalent concentration, about ten times less effective.