NUCLEAR AND ELECTRONIC RELAXATION IN LANTHANIDE SOLUTIONS - (CH3)(4)N+ GD3+ REPULSIVE ION-PAIR IN D2O/

The longitudinal relaxation rate and self-diffusion coefficient of the tetramethylammonium protons are investigated at 400 MHz in D2O soluti ons of hydrated Gd3+ paramagnetic impurities, without and with complex ing NO3- ions. The results are interpreted using the hypernetted chain approximation of the potential of mean force between the repulsive io ns, approximated as charged hard spheres in discrete polar and polariz able water. The standard dipolar relaxation formalism of Solomon is va lid for the Gd3+ lanthanide, i.e. its electron relaxation time is much longer than the translational correlation time of the interionic Brow nian diffusion. The coordination effect by NO3- is analyzed. (C) 1998 Elsevier Science B.V.