This approach can be justified considering that the very many interactions occurring between the many solvent molecules and the macromolecules are modulated with a variety of correlation times, due to the different time constants for the internal dynamics of the macromolecule, the anisotropy of its reorientation time (in case of non-spherical macromolecules) and the different solvent lifetimes. The correlation time for each interaction can be described by the relationship 𝜏 𝑐 -1 = 𝜏 𝑅 -1 + 𝜏 𝑓 -1 + 𝜏 𝑀 , where 𝜏 𝑅 is the reorientation time of the macromolecule (assumed spherical), 𝜏 𝑓 the internal local mobility experienced by a b that specific nuclear pair and 𝜏 𝑀 its lifetime. In the presence of large macromolecular systems, the reorientation time is likely the largest of the 𝜏 𝑐(𝑛) values, in the absence of fractional macromolecular aggregation.