Breakdown of Onsager’s conjecture on distance dependent polarization relaxation in solvation dynamics

Onsager’s conjecture that the polarization relaxation of solvent molecules closer to a newly created ion occurs slower than those which are far away is examined by using a molecular theory. We find that although Onsager’s conjecture is correct when only the rotational diffusion mechanism of polarization relaxation is considered, it breaks down completely for a significant translational contribution to polarization relaxation. The consequences of this result in solvation dynamics of ions and dipoles are discussed.