Viscosity decoupling does not guarantee dynamic heterogeneity: A way out

Does Viscosity Decoupling Guarantee Dynamic Heterogeneity? A Clue through an Excitation and Emission Wavelength-Dependent Time-Resolved Fluorescence Anisotropy Study

“…In the earlier report, we solved the problem by selectively probing different translational diffusiontime regimes from the fluorescence autocorrelations. 67 Thereafter, evaluating their temperature evolution from the same measurement and thus eliminating the effect of the solvent continuum, nonrigidity of solute, and so on, we contemplated the p-value for each diffusion-time regime. We proved that for translational dynamics, it is not the absolute p-value; instead, a difference in the p-value for different subpopulations is a better parameter to assess solvent heterogeneity.…”

“…To tackle this problem, one needs to separate how much deviation of the p -value originates from the departures of basic assumptions in SE/SED and how much is from the dynamic heterogeneity in the system. In the earlier report, we solved the problem by selectively probing different translational diffusion-time regimes from the fluorescence autocorrelations . Thereafter, evaluating their temperature evolution from the same measurement and thus eliminating the effect of the solvent continuum, nonrigidity of solute, and so on, we contemplated the p -value for each diffusion-time regime.…”

“…We proved that for translational dynamics, it is not the absolute p-value; instead, a difference in the p-value for different subpopulations is a better parameter to assess solvent heterogeneity. 67 Here, we determine the dynamic heterogeneity of a system in terms of rotational motion combining two well-known concepts, i.e., photoselecting different subpopulations as in the REES and viscosity decoupled dynamics as a signature of dynamic heterogeneity. We already discussed a different temperature-dependent microviscosity of the microdomains as the reason for dynamic heterogeneity.…”

Noncanonical Relationship between Heterogeneity and the Stokes–Einstein Breakdown in Deep Eutectic Solvents

“…), it was shown that viscosity decoupling does not guarantee dynamical heterogeneity and rather exhibits a dependence on diffusion time-regimes. 26,27 Similarly, studies exploring multiple length and time scales indicate that the relationship between SEB and DH is rather scale dependent. 28 The nature of the relationship between DH and SEB has been a longstanding issue.…”

“…Exploring the DH-SEB relationship at length scales larger than addressed in the present study might therefore provide interesting insights into the scale dependence of this complex relationship, which might emerge due to the distinct structural landscapes observed at these different length scales. While recent studies have indeed evidenced a scale dependence of SEB, 26,28 a detailed multiscale approach independently characterizing DH and SEB will help establish the structural origin of their relationship.…”